Table of Content

18 January 2015, Volume 26 Issue 1

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Responses of rhizosphere nitrogen and phosphorus transformations to different acid rain intensities in a hilly red soil tea plantation.

CHEN Xi1, CHEN Fu-sheng2, YE Su-qiong3, YU Su-qin2, FANG Xiang-min2, HU Xiao-fei1

2015, 26(1):  1-8. 

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Tea (Camellia sinensis) plantation in hilly red soil region has been long impacted by acid deposition, however its effects on nitrogen (N) and phosphorus (P) transformations in rhizosphere soils remain unclear. A 25year old tea plantation in a typical hilly red soil region was selected for an in situ simulation experiment treated by pH 4.5, pH 3.5, pH 2.5 and control. Rhizosphere and bulk soils were collected in the third year from the simulated acid deposition experiment. Soil mineral N, available P contents and major enzyme activities were analyzed using the chemical extraction and biochemical methods, and N and P mineralization rates were estimated using the indoor aerobic incubation methods. Our results showed that compared to the control, the treatments of pH 4.5, pH 3.5 and pH 2.5, respectively decreased 7.1%, 42.1% and 49.9% NO₃^--N, 6.4%, 35.9% and 40.3% mineral N, 10.5%, 41.1% and 46.9% available P, 18.7%, 30.1% and 44.7% ammonification rate, 3.6%, 12.7% and 38.8% net Nmineralization rate, and 31.5%, 41.8% and 63.0% P mineralization rate in rhizosphere soils; however, among the 4 treatments, rhizosphere soil nitrification rate was not significantly different, the rhizosphere soil urease and acid phosphatase activities generally increased with the increasing intensity of acid rain (P<0.05). In bulk soil, compared with the control, the treatments of pH 4.5, pH 3.5 and pH 2.5 did not cause significant changes in NO₃^--N, mineral N, available P as well as in the rates of nitrification, ammonification, net Nmineralization and P mineralization. With increasing the acid intensity, the rhizosphere effects of NH₄⁺-N, NO₃^--N, mineral N, ammonification and net Nmineralization rates were altered from positive to negative effects, those of urease and acid phosphatease showed the opposite trends, those of available P and P mineralization were negative and that of nitrification was positive. In sum, prolonged elevated acid rain could reduce N and P transformation rates, decrease their availability, alter their rhizosphere effects, and have impact on nutrient cycling in tea plantation.

 

Ecological stoichiometry of soil carbon, nitrogen and phosphorus within soil aggregates in tea plantations with different ages.

LI Wei, ZHENG Zi-cheng, LI Ting-xuan

2015, 26(1):  9-16. 

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This study selected 4 tea plantations with different ages (12-15, 20-22, 30-33 and >50  year old) located in Ya’an, Sichuan Province, China to investigate the distribution patterns of soil organic carbon (SOC), total nitrogen (TN) and total phosphorus (TP), and to examine the ecological stoichiometric characteristics of C, N and P within soil aggregates. The results showed that the coefficients of variation of SOC, TN and TP were 17.5%, 16.3% and 9.4%, respectively in the 0-20 cm soil layer and were 24.0%, 21.0% and 9.2%, respectively in the 20-40 cm soil layer. The spatial variation of TP was lower than that of SOC and TN but there were significant positive correlations among them. SOC and TN were distributed in the smallsize aggregates and both of them had the greatest values in the >50 yearold tea plantation, however, the distribution of TP was relatively uniform among aggregates and ages. The coefficients of variation of C/N, C/P, and N/P were 9.4%, 14.0% and 14.9%, respectively in the 0-20 cm soil layer and were 7.4%, 24.9% and 21.8%, respectively in the 20-40 cm soil layer. Variation of C/N was lower than that of C/P and N/P. Averaged C/P and N/P values in the smallsize aggregates were higher than in aggregates of other sizes, and the maximum values were in the >50 yearold plantation. C/N, C/P and N/P had good indication for soil organic carbon storage.

Effects of ozone stress on photosynthesis and dry matter production of rice Ⅱyou 084 under different planting densities.

PENG Bin1,2, LAI Shang-kun1, LI Pan-lin1, WANG Yun-xia1, ZHU Jian-guo3, YANG Lian-xin1, WANG Yu-long1

2015, 26(1):  17-24. 

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In order to investigate the effects of ozone stress on photosynthesis, dry matter production, non-structural carbohydrate and yield formation of rice, a free air ozone concentration  enrichment (FACE) experiment was conducted. A super hybrid rice cultivar Ⅱyou 084 with 3 spacing levels, low plant density (LD, 16 hills per m^-2), medium (MD, 24 hills per m^-2) and high plant density (HD, 32 hills per m^-2), was grown in the field at current and elevated ozone concentrations (current×1.5). The results were as follows: Elevated ozone significantly reduced leaf SPAD value of Ⅱyou 084 by 6%, 11% and 13%, at 63, 77, and 86 days after transplanting, respectively. The declines in leaf net photosynthetic rate, stomatal conductance and transpiration rate at filling stage increased significantly on ozone stress over time. Ozone stress decreased dry matter production of rice by 46% from heading stage to plant maturity, thus reduced biomass yield by 25%. Elevated ozone decreased the concentration and accumulation of soluble carbohydrate and starch in stem of Ⅱyou 084 at jointing, heading and plant maturity, but significantly increased the dry matter transportation rate. No significant interaction was observed between ozone and planting density for photosynthesis, dry matter production and nonstructural carbohydrate of rice. The above results indicated that elevated ozone reduced photosynthesis and growth of rice Ⅱyou 084 at late growth stage, which had no relationship with planting density.

Effects of silicon supply on rice growth and methane emission from paddy soil under elevated UV-B radiation.

MENG Yan1, LOU Yun-sheng1, WU Lei1, CUI He-yang2, WANG Wei-qing2

2015, 26(1):  25-31. 

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A pot experiment was conducted to investigate the effects of silicon supply on rice growth and methane (CH₄) emission in paddy field under elevated UV-B radiation. The experiment was designed with two UV-B radiation levels, i.e. ambient UV-B (ambient, A) and elevated UV-B radiation (elevated by 20%, E); with four silicon supply levels, i.e., Si₀ (control, without silicon), Si₁ (as sodium silicate, 100 kg SiO₂·hm^-2) ， Si₂ (as sodium silicate, 200 kg SiO₂·hm^-2) and Si₃ (as slag fertilizer, 200 kg SiO₂·hm^-2). The results indicated that, silicon supply obviously alleviated the depressive effect of elevated UV-B radiation on rice growth, and increased the tiller numbers, chlorophyll content, and shoot and root dry masses. Silicon supply promoted rice growth, which increased with the silicon supply level (sodium silicate). Slag fertilizer was better than sodium silicate in promoting rice growth. CH₄ flux and accumulated CH₄ emission were obviously increased by elevated UV-B radiation, but significantly decreased by silicon application. CH₄ emission was reduced with increasing the silicon supply level. Under the same silicon supply level, slag fertilizer was better than sodium silicate in inhibiting CH₄ flux and accumulated CH₄ emission. This research suggested that fertilizing slag in rice production was helpful not only in utilizing industrial wastes, but also in significantly mitigating CH₄ emissions in rice paddy under elevated UV-B radiation.

Effects of silicon supply on diurnal variations of physiological properties at rice heading stage under elevated UV-B radiation.

WU Lei1, LOU Yun-sheng1, MENG Yan1, WANG Wei-qing2, CUI He-yang2

2015, 26(1):  32-38. 

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A pot experiment was conducted to investigate the effects of silicon (Si) supply on diurnal variations of photosynthesis and transpirationrelated physiological parameters at rice heading stage under elevated UV-B radiation. The experiment was designed with two UV-B radiation levels, i.e. ambient UV-B (ambient, A) and elevated UV-B (elevated by 20%, E), and four Si supply levels, i.e. Si₀ (control, 0 kg SiO₂·hm^-2), Si₁ (sodium silicate, 100 kg SiO₂·hm^-2), Si₂ (sodium silicate, 200 kg SiO₂·hm^-2), Si₃ (slag fertilizer, 200 kg SiO₂·hm^-2). The results showed that, compared with ambient UV-B radiation, elevated UV-B radiation decreased the net photosynthesis rate (P_n), intercellular CO₂ concentration (C_i), transpiration rate (T_r), stomatal conductivity (g_s) and water use efficiency (WUE) by 11.3%, 5.5%, 10.4%, 20.3% and 6.3%, respectively, in the treatment without Si supply (Si₀ level), and decreased the above parameters by 3.8%-5.5%, 0.7%-4.8%, 4.0%-8.7%, 7.4%-20.2% and 0.7%-5.9% in the treatments with Si supply (Si₁, Si₂ and Si₃ levels), respectively. Namely, elevated UV-B radiation decreased the photosynthesis and transpirationrelated physiological parameters, but silicon supply could obviously mitigate the depressive effects of elevated UV-B radiation. Under elevated UV-B radiation, compared with control (Si₀ level), silicon supply increased P_n, C_i, g_s and WUE by 16.9%-28.0%, 3.5%-14.3%, 16.8%-38.7% and 29.0%-51.2%, respectively, but decreased T_r by 1.9%-10.8% in the treatments with Si supply (Si₁, Si₂ and Si₃ levels). That is, silicon supply could mitigate the depressive effects of elevated UVB radiation through significantly increasing P_n, C_i, g_s and WUE, but decreasing T_r. However, the difference existed in ameliorating the depressive effects of elevated UV-B radiation on diurnal variations of physiological parameters among the treatments of silicon supply, with the sequence of Si₃>Si₂>Si₁>S/a#₀. This study suggested that fertilizing slag was helpful not only in recycling industrial wastes, but also in effectively mitigating the depressive effects of elevated UV-B radiation on photosynthesis and transpiration in rice production.

Effects of enhanced UV-B radiation on culm charateristics and lodging index of two local rice varieties in Yuanyang terraces under field condition.

HE Yong-mei, ZHAN Fang-dong, ZU Yan-qun, XU Wei-wei, LI Yuan

2015, 26(1):  39-45. 

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Two local rice varieties (Baijiaolaojing and Yuelianggu) were cultivated in situ in Yuanyang terraces, China, in 2012 and 2013 to investigate the effect of enhanced UV-B radiation condition (0, 2.5, 5.0 and 7.5 kJ·m^-2) on internode characteristics including length, culm diameter, culm wall thickness from the first to the fourth internode, as well as the lodging index. The results showed that UV-B radiation had no significant influence on internode length and culm, but significantly reduced the culm wall thickness, with that of the fourth internode region decreased by 11.6% to 19.6% under 7.5 kJ·m^-2 UV-B radiation. The enhanced UV-B radiation increased the lodging index of rice varieties, making them more prone to lodging. The fourth internode had the highest lodging index which was higher than the lodging critical value (200). The decrease in culm wall thickness due to the enhanced UV-B radiation could be responsible for the increasing lodging risk of rice varieties grown in Yuanyang terraces.

 

Effect of light from flowering to maturity stage on dry matter accumulation and nutrient absorption of summer maize.

SHI Jian-guo, ZHU Kun-lun, CAO Hui-ying, DONG Shu-ting, LIU Peng, ZHAO Bin, ZHANG Ji-wang

2015, 26(1):  46-52. 

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Using Denghai 605 (DH605) as the experimental material, shading (S) and increasing light (L) treatments from flowering to maturity stage were designed in a field experiment to explore effects of light on dry matter accumulation and nutrient absorption of summer maize. Results showed that grain yield, dry matter accumulation and nutrient absorption decreased significantly after shading but increased after increasing light. Yields in S treatment from 2011 to 2013 were reduced by 59.4%, 79.0% and 60.6% compared to those in CK, while that in L treatment were increased by 16.3%, 12.9% and 6.8%, respectively. The relative N and P absorption increased to a certain extent because of the greater effect of shading on dry matter accumulation than that of N and P absorption. After shading, K absorption of whole plant corn decreased significantly to a greater extent than that of dry matter accumulation decrease. The proportion of nutrient allocated to grains decreased significantly after shading. Dry matter accumulation and N and P absorption rates increased significantly after increasing light, and effects of increasing light on N and P absorption were greater than that of dry matter accumulation. Nutrient accumulation and the proportion allocated to grain increased significantly after increasing light.

 

Responses of non=structural carbohydrate  metabolism of cucumber seedlings to drought stress and doubled CO₂ concentration.

DONG Yan-hong1, LIU Bin-bin2, ZHANG Xu1, LIU Xue-na1, AI Xi-zhen1,2, LI Qing-ming1,2,3

2015, 26(1):  53-60. 

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The effects of doubled CO₂ concentration on non-structural carbohydrate metabolism of cucumber (Cucumis sativus L. cv. ‘Jinyou No.1’) seedlings under drought stress were investigated. Split plot design was deployed, with two levels of CO₂ concentrations (ambient CO₂ concentration, 380 μmol·mol^-1, and doubled CO₂ concentration, 760±20 μmol·mol^-1) in the main plots, and three levels of water treatments (control, moderate drought stress, and severe drought stress) simulated by PEG 6000 in the splitplots. The results showed that nonstructural carbohydrates of cucumber leaves, including glucose, fructose, sucrose, and stachyose, increased with the doubling of CO₂ concentration, which resulted in the decreased osmotic potential, improving the drought stress in cucumber seedlings. During the drought stress, sucrose synthase, soluble acid invertase and alkaline invertase started with an increase, and followed with a decline in the leaves. In the root system, however, soluble acid invertase and alkaline invertase increased gradually throughout the whole process, whereas sucrose phosphate synthase firstly increased and then decreased. The treatment of doubled CO₂ enhanced the activity of sucrose synthase, but decreased the activity of sucrose phosphate synthase. The synergistic action of the two enzymes and invertase accelerated the decomposition of sucrose and inhibited the synthesis of sucrose, leading to the accumulation of hexose, which lowered the cellular osmotic potential and enhanced the water uptake capacity. In conclusion, doubled CO₂ concentration could alleviate the adverse effects of drought stress and improve the drought tolerance of cucumber seedlings. Such mitigating effect on cucumber was more significant under severe drought stress.

 

Physiological response of corn seedlings to changes of wind-sand flow strength.

ZHAO Ha-lin1, LI Jin1, ZHOU Rui-lian2, QU Hao1, YUN Jian-ying1, PAN Cheng-chen1

2015, 26(1):  61-66. 

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Corn seedlings are often harmed by strong wind-sand in the spring in semiarid windsand area of west of Northeast China. In order to understand physiological response mechanisms of the corn seedlings to windsand damage, the changes in MDA content, membrane permeability, protective enzymes activities and osmotic regulation substances at 0 (CK), 6, 9, 12, 15 and 18 m·s^-1 wind speed (wind-sand flow strength: 0, 1.00, 28.30, 63.28, 111.82 and 172.93 g·cm^-1·min^-1, respectively) for 10 min duration were studied during the spring, 2013 in the Horqin Sand Land of Inner Mongolia. The results showed that effects of windsand flow blowing on the RWC of the corn seedling were lighter in the 6-12 m·s^-1 treatments, but the RWC decreased by 19.0% and 18.7% in the 15 m·s^-1 and 18 m·s^-1 treatments compared to the CK, respectively. The MDA content tended to decline with increasing the wind-sand flow strength, and decreased by 35.0% and 39.0% in the 15 m·s^-1 and 18 m·s^-1 treatments compared to the CK, respectively. The membrane permeability increased significantly with increasing the windsand flow strength, and increased by 191.3% and 187.8% in the 15 m·s^-1 and 18 m·s^-1 treatments compared to the CK, respectively. With the increase of windsand flow strength, SOD activities decreased and changes of CAT activities were not significant, only POD activities increased significantly, which played an important role in the process of scavenging reactive oxygen species and protecting cell membrane against damage. For lighter water stress caused by windsand flow blowing, proline and soluble sugar did not play any role in osmotic adjustment, but the proline content increased by 11.4% and 24.5% in the 15 m·s^-1 and 18 m·s^-1 treatments compared to the CK, respectively, which played an important role in osmotic adjustment.

 

Effects of air temperature increase and precipitation change on grain yield and quality of spring wheat in semiarid area of Northwest China.

WANG He-ling1, ZHANG Qiang1, WANG Run-yuan1, GAN Yan-tai2, NIU Jun-yi3, ZHANG Kai1, ZHAO Fu-nian1, ZHAO Hong1

2015, 26(1):  67-75. 

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In order to predict effects of climate changing on growth, quality and grain yields of spring wheat, a field experiment was conducted to investigate the effects of air temperature increases (0 ℃, 1.0 ℃, 2.0 ℃ and 3.0 ℃) and precipitation variations (decrease 20%, unchanging and increase 20%) on grain yields, quality, diseases and insect pests of spring wheat at the Dingxi Arid Meteorology and Ecological Environment Experimental Station of the Institute of Arid Meteorology of China Meteorological Administration(35°35′ N,104°37′ E). The results showed that effects of precipitation variations on kernel numbers of spring wheat were not significant when temperature increased by less than 2.0 ℃, but was significant when temperature increased by 3.0 ℃. Temperature increase enhanced kernel numbers, while temperature decrease reduced kernel numbers. The negative effect of temperature on thousandkernel mass of spring wheat increased with increasing air temperature. The sterile spikelet of spring wheat response to air temperature was quadratic under all precipitation regimes. Compared with control (no temperature increase), the decreases of grain yield of spring wheat when air temperature increased by 1.0 ℃, 2.0 ℃ and 3.0 ℃ under each of the three precipitation conditions (decrease 20%, no changing and increase 20%) were 12.1%, 24.7% and 42.7%, 8.4%, 15.1% and 21.8%, and 9.0%, 15.5% and 22.2%, respectively. The starch content of spring wheat decreased and the protein content increased with increasing air temperature. The number of aphids increased when air temperature increased by 2.0 ℃, but decreased when air temperature increased by 3.0 ℃. The infection rates of rust disease increased with increasing air temperature.

 

Nitrogen cycling and balance for wheat in China.

CHUAN Li-min1,2, HE Ping2, ZHAO Tong-ke3, XU Xin-peng2, ZHOU Wei2, ZHENG Huai-guo1

2015, 26(1):  76-86. 

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In this study, the input and output parameters of N for wheat production were collected from published literatures and International Plant Nutrition Institute in the period of 2000 to 2011 to evaluate N cycling and balances in North  China, the middle and lower reaches of Yangtze River and Northwest China. The results showed that the N fertilizer application rates for each region were 170, 183 and 150 kg N·hm^-2, the amounts of N from the previous crop were 74.6, 15.2 and 8.1 kg N·hm^-2, and from seeds were 4.9, 4.2 and 3.5 kg N·hm^-2, respectively. The N inputs from symbiotic fixation, atmospheric deposition and irrigation water in North  China were 15, 12.9 and 9.9 kg N·hm^-2, and in the middle and lower reaches of Yangtze River were 15, 14.5 and 5.8 kg N·hm^-2, and in Northwest China were 15, 9.4 and 7.7 kg N·hm^-2, respectively. The amounts of N uptake by aboveground plant at  harvest time in North  China, the middle and lower reaches of Yangtze River and Northwest China were 174.3, 144.4 and 122.3 kg N·hm^-2, respectively, and the rates of ammonia volatilization, N₂O emission and N leaching in North  China were 19.9, 2.6 and 11.8 kg N·hm^-2, in the middle and lower reaches of Yangtze River were 9.4, 2.4 and 15.5 kg N·hm^-2, and in Northwest China were 3.4, 0.7 and 0 kg N·hm^-2, respectively. As a result, the N balances in these three regions were all showing surpluses by 78.7, 66.0 and 67.3 kg N·hm^-2. It is therefore necessary to adjust the N fertilizer application rates in these three regions to avoid the negative impacts on the environment.


 

Carbon efficiency of double-rice production system in Hunan Province, China.

CHEN Zhong-du1, WU Yao1, TI Jin-song1, CHEN Fu1, LI Yong2

2015, 26(1):  87-92. 

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Improving the carbon efficiency of crop production systems is one of the important ways to realize low-carbon agriculture. A life cycle assessment approach and inputoutput calculation method was applied for a doublerice production system in the Hunan Province. Based on statistical data of crop yield and investment in the production system in the period from 2004 to 2012, carbon emission, carbon absorption, carbon efficiency and their dynamic changes of the double rice production systems were estimated. The results showed that the average of annual carbon emission from 2004 to 2012 was 656.4×10⁷ kg CE. Carbon emissions from production and transport of fertilizer and pesticide accounted for a majority of agricultural input carbon emissions, approximately 70.0% and 15.9%, respectively. The carbon emission showed a decreasing trend from 2004 to 2012 in the Hunan Province, with an annual reduction rate of 2.4%, but the carbon emission intensity was in a trend of increase. The average of annual carbon absorption was 1547.0×10⁷ kg C. The annual carbon absorption also showed a decreasing trend from 2004 to 2012 in Hunan Province, with an average annual reduction rate of 1.2%, and the carbon absorption intensity showed a trend of increase. Furthermore, production efficiency of carbon showed a slow upward trend. The economic efficiency of carbon showed a larger increasing rate with time, with an average annual growth rate of 9.9%. Ecological efficiency of carbon was stable and low, maintained at about 2.4 kg C·kg^-1 CE. It indicated that the integrated carbon efficiency of Hunan double rice crop production system improved slowly with time and the key to improve the carbon efficiency of double rice production systems lies in reducing the rates of nitrogen fertilizer and pesticide, and improving their use efficiencies.

 

Effect of long-term fertilization on lignin accumulation in typical subtropical upland soil.

FENG Shu-zhen1,2，3, CHEN Xiang-bi1,3, HE Xun-yang1,3, DONG Ming-zhe1,2, QIU Hu-sen1,2, SU Yi-rong1,3

2015, 26(1):  93-100. 

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To investigate the effect of longterm fertilization on lignin accumulation and clarify its influencing factors in subtropical agricultural upland soils, alkaline CuO oxidation and gas chromatography was performed to quantify the amount of lignin and its monomers components (V, S and C). The soil samples were collected from the fertilization treatments of NPK and NPKS (NPK combined with straw) in Huanjiang County, Guangxi Province (limestone soil) and Taoyuan County, Hunan Province (red soil). The results showed that NPK had no significant effect on the lignin content (Sum_VSC) of limestone soil, whereas the content in red soil significantly increased by (55±1)%. For the NPKS treatment, the lignin content in limestone and red soil increased by (328±4)% and (456±9)%, respectively. After the same fertilization treatment, the proportion of cinnamyl (C)type significantly increased in red soil, while a significant increase of vanillyl (V)type monomers occurred in limestone soil, indicating that lignin degradation in agricultural soils was monomer specific. Furthermore, the acidtoaldehyde ratios of syringyltype \[(Ac/Al) _S\] or vanillyltype \[(Ac/Al) _V\] monomers tended to decrease after long-term fertilization with the higher value for limestone soil, suggesting the degree of lignin degradation in limestone was higher than that in red soil. Soil organic matter and total nitrogen were not correlated with lignin content, but were significantly correlated with the composition of VSC monomers. Meanwhile, the available nutrient content in the soil (available nitrogen, phosphorus, and potassium) was closely related to the contents and components of V, S, and Ctype monomers (P<0.05). It indicated that the availability of soil nutrition should be considered as a key factor for the accumulation of lignin.

 

Impact of tillage practices on microbial biomass carbon in top layer of black soils.

SUN Bing-jie1,2, JIA Shu-xia1, ZHANG Xiao-ping1, LIANG Ai-zhen1, CHEN Xue-wen1, ZHANG Shi-xiu1, LIU Si-yi1,2, CHEN Sheng-long1,2

2015, 26(1):  101-107. 

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A study was conducted on a longterm (13 years) tillage and rotation experiment on black soil in northeast China to determine the effects of tillage, time and soil depth on soil microbial biomass carbon (MBC). Tillage systems included no tillage (NT), ridge tillage (RT) and mouldboard plough (MP). Soil sampling was done at 0-5, 5-10 and 10-20 cm depths in June, August and September, 2013, and April, 2014 in the corn phase of cornsoybean rotation plots. MBC content was measured by the chloroform fumigation extraction (CFE) method. The results showed that the MBC content varied with sampling time and soil depth. Soil MBC content was the lowest in April for all three tillage systems, and was highest in June for MP, and highest in August for NT and RT. At each sampling time, tillage system had a significant effect on soil MBC content only in the top 0-5 cm layer. The MBC content showed obvious stratification under NT and RT with a higher MBC content in the top 0-5 cm layer than under MP. The stratification ratios under NT and RT were greatest in September when they were respectively 67.8% and 95.5% greater than under MP. Our results showed that soil MBC contents were greatly affected by the time and soil depth, and were more apparently accumulated in the top layer under NT and RT.

Soil C, P and microbial biomass C, P response to different fertilizations in the hillslope cropland of purple soil.

GAO Yang1,5, XU Ya-juan2, PENG Yan1,3, JIN Jin1,4, ZHU Bo5, YU Gui-rui1

2015, 26(1):  108-112. 

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The aim of this study is to explore the changes and coupling characteristics of carbon (C), phosphorus (P) and microbial C, P in a hillslope cropland of purple soil. The results showed that total organic carbon (TOC) ranged from 90.8 to 100.8 g·kg^-1 under organic fertilizer or straw combined with inorganic fertilizer treatments (including N, NP and NPK) as compared with nitrogen (N) application only (62.2 g·kg^-1). Total phosphorus (TP) ranged from 0.65 to 0.84 g·kg^-1 in organic combined with inorganic fertilization treatments, and that under straw combined with inorganic fertilizer treatments was 23%-38% of organic fertilizer combined with inorganic fertilization treatments. The microbial biomass phosphorus (MBP) under N fertilizer was significantly decreased as compared with combined fertilization treatments. The ratios of microbial biomass carbon (MBC) to MBP under combined fertilization treatments were between 5 to 26, and the TOC/TP ratios under organic fertilizer and straw combined treatments were between 92 to 137 and 296 to 653, respectively, while those under N fertilizer treatment were 59 and 2000, respectively. The results indicated that combined organic and inorganic fertilizers would be helpful for enhancing P availability and increasing its potential capacity in purple soil.

Effects of irrigation and fertilization on soil microbial properties in summer maize field.

LIU Zhen-xiang1,2, LIU Peng1, JIA Xu-cun1, CHENG Yi1, DONG Shu-ting1, ZHAO Bin1, ZHANG Ji-wang1, YANG Jin-sheng3

2015, 26(1):  113-121. 

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In order to investigate the effects of different irrigation and fertilization on soil microbial properties of summer maize field, we used ZN99 with high nitrogen use efficiency as the test material. The experiment adopted the split plot design which included two irrigation levels (526 mm and 263 mm) as the main plots, three fertilizer types (U, M, UM) and two fertilizer levels (N 100 kg·hm^-2 and 200 kg·hm^-2) as the subplots. The  results showed that the irrigation level affected the regulating effects of fertilizer on soil microbial biomass (carbon and  nitrogen) and microbial diversity. The organic fertilizer application must be under the sufficient irrigation level to increase the soil MBC (14.3%-33.6%), MBN(1.8-2.3 times) and abundance significantly. A moderate rate of irrigation, higher rates of organic fertilizer application or organic manure combined with inorganic fertilizer could increase the nitrogenfixation species and quantity of Firmicutes, γ-Proteobacteria and α-Proteobacteria in the soil. Under the same N level, there was no significant difference of grain yield between organic manure and inorganic fertilizer treatments. Considering sustainable production, proper organic manure application with moderate irrigation could increase the quantity of the soil microbial biomass and microbial diversity, and improve the capacity of soil to supply water and nutrients.

 

Effects of tillage type on soil organic carbon and its distribution in oasis irrigation area.

MA Zhong-ming1, LYU Xiao-dong1, LIU Li-li2

2015, 26(1):  122-128. 

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A longterm trial was established in 2005 in the oasis irrigation area to determine the impact on the accumulation and distribution of total organic carbon (TOC), particulate organic carbon (POC) and soil microbial biomass carbon (SMBC) in 0-90 cm soil layer of 4 types of tillage including conventional tillage (CT), fresh raisedbed (FRB), permanent raisedbed (PRB) and zero tillage with control traffic on flat field (ZT). The results revealed that the distribution characteristics of TOC, POC and SMBC in the soil profile were similar in the four tillage treatments, and the carbon content decreased with depth, meanwhile the difference among treatments gradually decreased. PRB significantly increased the  TOC, POC contents and SMBC, which presented in the order of PRB>ZT>FRB>CT in the 0-90 cm soil layer. In 0-10 cm soil layer, the TOC was increased by 11.1%-24.8% for PRB, 9.1%-18.7% for ZT and 7.8%-8.2% for FRB when compared with CT; POC was increased by 24.1%-26.5% for PRB, 17.3%-18.7% for ZT, and -8.2% to 10.8% for FRB; SMBC was increased by 20.5%-28.3% for PRB, 10.4%-15.2% for ZT and 3.5%-3.7% for FRB.  TOC had a significant promotion effect on POC. PRB significantly increased the proportion of soil POC and enhanced the overall accumulation of organic carbon.

Effects of different fertilization measures on N₂O emission in oil sunflower field in irrigation area of upper Yellow River.

CHEN Zhe1, CHEN Yuan-yuan2, GAO Ji3, LIU Ru-liang4, YANG Zheng-li1, ZHANG Ai-ping1

2015, 26(1):  129-139. 

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Agricultural soil has become the largest anthropogenic source of atmospheric nitrous oxide (N₂O). To estimate the impacts of longterm combined application of organic and inorganic fertilizers on N₂O emission in a typical winter wheatoil sunflower cropping system in the Ningxia irrigation area, we measured N₂O fluxes using the static opaque chambergas chromatograph method and monitored the seasonal dynamics of related factors. Our results showed that nitrogen addition in the previous crop field significantly stimulated N₂O emissions during the following oil-sunflower cultivation, and the mean fluxes of N₃₀₀-OM, N₂₄₀-OM_1/2, N₃₀₀ and N₂₄₀ were (34.16+9.72), (39.69+10.70), (27.75+9.57) and (26.30+8.52) μg·m^-2·h^-1, respectively, which were 4.09, 4.75, 3.32 and 3.15 times of the control groups. The total cumulative N₂O emissions of fertilizer treatments in growing season was as high as  796.7 to 1242.5 g·hm^-2, which was  2.99 to 4.67 times of the control groups. During the growing season, the rates of N₂O emission in each month organic and inorganic fertilizers combined treatments were similar at high levels. N₂O emission in chemical fertilizer treatments gradually decreased, and the main period of N₂O emission occurred at the beginning of growing season. Taking July for example, N₂O emission accounted for 41.3% to 418% of total cumulative amount. The amounts of N₂O emission under organic and inorganic fertilizers
 combined treatments were significantly higher than under chemical fertilizer treatments. The N₂O emissions were not significantly different between conventional and optimized applications of nitrogen fertilizer under the same fertilizing method, either between N₃₀₀-OM and N₂₄₀-OM_1/2, or between N₃₀₀ and N₂₄₀. On account of the drought, N₂O emission in each treatment was mainly affected by soil moisture. N₂O emission had a significant positive correlation with soil ammonium nitrogen content under combined applications of organic and inorganic fertilizers, but was not correlated with soil nitrate nitrogen content under all treatments. This showed that adding organic fertilizer could stimulate the N₂O production via increasing the soil ammonium nitrogen content.

 

Short-term response of soil CH₄ flux to simulated precipitation in a winter wheat field on the Loess Plateau, Northwest China. 〖STBZ〗

LIU Quan-quan1, WANG Jun1, CHEN Rong-rong1, LIU Wen-zhao2, Upendra M. Sainju3

2015, 26(1):  140-146. 

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To understand the short-term response of soil CH₄ flux to different precipitation events in a winter wheat field on the Loess Plateau, we conducted precipitation simulation experiments during winter wheat jointing stage and summer fallow period to measure the soil CH₄ flux in 0 to 72 h after precipitation simulation of 1 to 32 mm. Results showed that CH₄ flux during 0 to 72 h fluctuated at 1 to 8 mm of precipitation application and peaked at 16 and 32 mm. Cumulative CH₄ flux after 72 h of precipitation (CH₄-C) increased linearly with the precipitation amount (P) (wheat jointing stage: CH₄-C=2.45P-6.09, R²=0.92, P<0.01; summer fallow: CH₄-C=2.43P-4.73, R²=0.91, P<0.01). Statistical analysis showed that CH₄ flux was also correlated with soil water content and microbial biomass carbon but not with soil temperature. In the long run, small precipitation events (1-8 mm) could enhance the intensity of soil CH₄ sink and such promoting effect would be weakened with further increase in precipitation amount. However, large precipitation events (≥16 mm) could change the soil function from CH₄ sink to source by stimulating the activity of soil methanogens during shortterm periods.

Effects of land-use conversion from double rice cropping to vegetables on CO₂ and CH₄ fluxes in southern China.

YUAN Ye1,2, LIU Chang-hong3, DAI Xiao-qin1,4, WANG Hui-min1,4

2015, 26(1):  147-154. 

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In this study, the CO₂ and CH₄ fluxes in the first year after land use conversion from paddy rice to vegetables were measured by static opaque chamber and gaschromatograph (GC) method to investigate the land conversion effects on soil CO₂ and CH₄ emissions. Our results showed that the differences in CO₂ fluxes depended on the vegetable types, growing status and seasons. The CO₂ flux from the vegetable field was greater than that from the paddy rice field when cowpea was planted, but was lower when pepper was planted. The CH₄ flux significantly decreased from 6.96 mg C·m^-2·h^-1 to -0.004 mg C·m^-2·h^-1 with the land use conversion from rice to vegetables. The net  carbon absorption (CO₂ + CH₄) of the vegetable fields was 543 kg C·hm^-2, significantly lower than that (3641 kg C·hm^-2) of the rice paddies. However, no significant difference was found in their global warming impact. In addition, soil carbon content increased in vegetable fields compared to the paddy rice fields after a year of conversion, especially in the 10-20 cm soil layer.

Effects of plastic film mulching on soil CO₂ efflux and CO₂ concentration in an oasis cotton field.

YU Yong-xiang1,2, ZHAO Cheng-yi1, JIA Hong-tao3, YU Bo1,2, ZHOU Tian-he1,2, YANG Yu-guang1,2, ZHAO Hua4

2015, 26(1):  155-160. 

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A field study was conducted to compare soil CO₂ efflux and CO₂ concentration between mulched and non-mulched cotton fields by using closed chamber method and diffusion chamber technique. Soil CO₂ efflux and CO₂ concentration exhibited a similar seasonal pattern, decreasing from July to October. Mulched field had a lower soil CO₂ efflux but a higher CO₂ concentration, compared to those of nonmulched fields. Over the measurement period, cumulative CO₂ efflux was 1871.95 kg C·hm^-2 for mulched field and 2032.81 kg C·hm^-2 for nonmulched field. Soil CO₂ concentration was higher in mulched field (ranging from 5137 to 25945 μL·L^-1) than in nonmulched field (ranging from 2165 to 23986 μL·L^-1). The correlation coefficients between soil CO₂ concentrations at different depths and soil CO₂ effluxes were 0.60 to 0.73 and 0.57 to 0.75 for the mulched and nonmulched fields, indicating that soil CO₂ concentration played a crucial role in soil CO₂ emission. The Q₁₀ values were 2.77 and 2.48 for the mulched and non-mulched fields, respectively, suggesting that CO₂ efflux in mulched field was more sensitive to the temperature.

 

Effects of superphosphate addition on NH₃ and greenhouse gas emissions during vegetable waste composting.

YANG Yan1,2, SUN Qin-ping2, LI Ni2, LIU Chun-sheng1, LI Ji-jin2, LIU Ben-sheng2, ZOU Guo-yuan2

2015, 26(1):  161-167. 

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To study the effects of superphosphate (SP) on the NH₃ and greenhouse gas emissions, vegetable waste composting was performed for 27 days using 6 different treatments. In addition to the controls, five vegetable waste mixtures (0.77 m³ each) were treated with different amounts of the SP additive, namely, 5%, 10%, 15%, 20% and 25%. The ammonia volatilization loss and greenhouse gas emissions were measured during composting. Results indicated that the SP additive significantly decreased the ammonia volatilization and greenhouse gas emissions during vegetable waste composting. The additive reduced the total NH₃ emission by 4.0% to 16.7%. The total greenhouse gas emissions (CO₂-eq) of all treatments with SP additives were decreased by 10.2% to 20.8%, as compared with the controls. The NH₃ emission during vegetable waste composting had the highest contribution to the greenhouse effect caused by the four different gases. The amount of NH₃ (CO₂-eq) from each treatment ranged from 59.90 kg·t^-1 to 81.58 kg·t^-1; NH₃ (CO₂-eq) accounted for 69% to 77% of the total emissions from the four gases. Therefore, SP is a costeffective phosphorusbased fertilizer that can be used as an additive during vegetable waste composting to reduce the NH₃ and greenhouse gas emissions as well as to improve the value of compost as a fertilizer.

 

Effects of long-term tillage and rice straw returning on soil nutrient pools and Cd concentration.

TANG Wen-guang1, XIAO Xiao-ping1, TANG Hai-ming1, ZHANG Hai-lin2, CHEN Fu2, CHEN Zhong-du2, XUE Jian-fu2, YANG Guang-li1

2015, 26(1):  168-176. 

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The objective of this study was to assess the effects of tillage and straw returning on soil nutrient and its pools, and soil Cd concentration, and to identify the strategies for rational tillage and remediation of Cd contaminated paddy fields. The experiment was established with notillage with straw retention (NTS), rotary tillage with straw incorporation (RTS), conventional plow tillage with straw incorporation (CTS), conventional plow tillage with straw removed (CT) from 2005 to 2013. The results indicated that tillage and rice straw retention had a great impact on soil properties at 0-10 cm soil depth. The soil aeration, and concentrations of soil nutrient and soil Cd increased under CTS, CT, and RTS. Due to the shallow plow layers, soil nutrient pools and the Cd concentration in rice shoot decreased in long-term tilled soil. Under long-term no-tillage, the soil bulk, soil nutrient pools and Cd concentration in rice shoot increased, but concentrations of soil nutrients decreased. In addition, rice straw returning significantly increased the soil nutrient concentrations, cation exchange capacity, depth of plow layer, and soil nutrient pools. However, the Cd in the rice straw was also returned to the soil by rice straw returning, which would not benefit the remediation of soil Cd. Therefore, it is necessary to improve tillage and straw retention practices due to the disadvantages of longterm continuous single tillage method and rice straw returning practices. Some recommended managements (e.g., rotational tillage or subsoiling, reducing straw returning amount, and rotational straw returning) could be good options in enhancing soil fertility and remedying soil pollution.

 

Spatial variability of soil C/N ratio and its influence factors at a county scale in hilly area of Mid-Sichuan Basin, Southwest China.

LUO You-lin, LI Qi-quan, WANG Chang-quan, ZHANG Wei, ZHANG Hao, LI Lin-xian, CHEN Jun-wei, MA Yu

2015, 26(1):  177-185. 

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Spatial distribution characteristics of soil C/N ratio and its affecting factors at a county scale in hilly area of Middle Sichuan Basin were analyzed based on field sampling. Result indicated that soil C/N ranged from 4.84 to 21.79, with a mean value of 11.93. The coefficient of variation was 26.3%, which suggested soil C/N had moderate variability in this study area. The ratio of nugget to sill was 73.0%, which suggested the spatial variability of soil C/N was determined by both structural and random factors, and the random factors played a more important role. The soil C/N was higher in northeast and southwest while the central part of the study area was characterized by relatively lower values of soil C/N. The soil C/N ranged from 10.0 to 13.5 in most parts of the study area. Parent material, soil type, topographic factors and land use type had significant impacts on soil C/N (P<0.05). Soil C/N showed a significant positive correlation with elevation and slope (P<0.05). The soil parent materials were able to explain 8.7% of soil C/N spatial variability. The explanatory power of soil group, subgroup and soil genus were 3.8%, 5.0%, 8.7%, respectively. Topographic factors showed the lowest explanatory power of only 0.8%. However, land use type could explain 23.9% of the spatial variability, which suggested that land use type was the dominant factor in controlling the spatial variability of soil C/N.


 

Impacts of high temperature on  maize production  and adaptation measures in Northeast China.

YIN Xiao-gang1, WANG Meng1, KONG Qing-xin2, WANG Zhan-biao1, ZHANG Hai-lin1, CHU Qing-quan1, WEN Xin-ya1, CHEN Fu1

2015, 26(1):  186-198. 

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Heat stress is one of the major agro-meteorological hazards that affect maize production significantly in the  farming region of Northeast China (NFR). This study analyzed the temporal and spatial changes of the accumulated temperature above 30 ℃ (AT) and the accumulated days with the maximum temperature above 30 ℃ (AD) in different maize growing phases under global warming. It further evaluated the impacts of extreme heat on maize yield in different regions, and put forward some adaptation measures to cope with heat stress for maize production in NFR. The results showed that during 1961 to 2010, the temperature in the maize growing season increased significantly. The maximum temperature in flowering phase was much larger than that in the other growing phases. Temperature increased at rates of 0.16, 0.14, 0.06 and 0.23 ℃ every ten years in the whole maize growing season, vegetative growth phase (from sowing to 11 days before flowering), flowering phase, and late growth phase (from 11 days after flowering to maturity), respectively. The AT in the whole maize growing season increased in NFR during the last 50 years with the highest in the southwest part of NFR, and that in the vegetative growth phase increased faster than in the other two phases. The AD in the whole maize growing season increased during the last 50 years with the highest in the southwest part of NFR, and that in the late growth phase increased faster than in the other two phases. Heat stress negatively affected maize yield during the maize growing season, particularly in the vegetative growth phase. The heat stress in Songliao Plain was much higher in comparison to the other regions. The adaptation measures of maize production to heat stress in NFR included optimizing crop structure, cultivating high temperature resistant maize varieties, improving maize production management and developing the maize production system that could cope with disasters.

Agricultural policies and farming systems: A case study of landscape changes in Shizuitou Village in the recent four decades.

WANG Xiao-jun1, ZHOU Yang1, YAN Yan-bin2, LI Lei2

2015, 26(1):  199-206. 

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Agricultural policy in China’s rural heartland is driving profound changes to traditional farming systems. A case study covering four decades mapped and recorded farming patterns and processes in Shizuitou Village, a rural village in northwest Shanxi. An integrated geospatial methodology from geography and anthropology was employed in the case study to record the changing dynamics of farming systems in Shizuitou Village to discover the longterm impacts of China’s agricultural policies on village farming systems. Positive and negative impacts of agricultural policies on village farming systems were mapped, inventoried and evaluated using Participatory Geographic Information Systems (PGIS). The results revealed traditional polycultures are being gradually replaced by industrialized monocultures. The driving forces behind these farming changes come from a series of government agricultural policies aiming at modernization of farming systems in China. The goal of these policies was to spur rapid development of industrial agriculture under the guise of modernization but is leading to the decay of traditional farming systems
 in the village that maintained local food security with healthy land for hundreds of years. The paper concluded with a recommendation that in future, agricultural policy makers should strike a more reasonable balance between shortterm agricultural profits and longterm farming sustainability based on the principles of ecological sustainable development under the context of global changes.

 

Cultivated landscape pattern change due to the rice paddy expansion in Northeast China: A case study in Fujin.

DU Guo-ming1,2, PAN Tao1, YIN Zhe-rui1, DONG Jin-wei3

2015, 26(1):  207-214. 

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On the background of global climate change, agriculture in North China has been experiencing substantial modifications to adapt to the ongoing regional warming. One of the most significant land use change is the conversation from upland cropland to paddy cropland, which is characterized by the dramatic changes of agricultural landscape pattern. In this study, we generated land use maps in Fujin City in 2000 and 2013 by using Landsat TM imagery, and analyzed the landscape pattern changes (cropland composite, special distribution, and patch characteristics, etc.) of croplands by using landscape indices and empirical approach. The results indicated a rapid cropland increase from 512400 hm² (reclamation ratio 60.4%) in 2000 to 699300 hm² (reclamation 82.4%) in 2013, especially, the paddy cropland proportion in the total cropland increased from 6.7% to more than half (54.1%), that is, the agricultural land use mode had changed from the initial stage of paddy agriculture to the intermediate stage. The reclamation area and common agricultural area showed different paddy agriculture development characteristics: in 2000, the paddy field ratios in the common agricultural area and reclamation area were similar (5.5% and 8.3% respectively); however, in 2013, the paddy field ratio in the common agricultural area (33.6%) was significantly lower than that in reclamation area (83.4%). In 2000, the total number of cropland patches was 2311 in the study, including 1010 patches from the common agricultural area and 1301 patches from the reclamation area. The coefficient of variation (CV), and shape index (SI) of cropland patches in upland cropland were always higher than in paddy cropland. Upland cropland had larger mean patch size with the plaque area index above 60% and higher connectivity. The patch density of upland cropland was lower than that of paddy cropland. In the conversions to the intermediate and later stages of paddy agriculture, the patch number of cropland increased rapidly with different rates in upland and paddy croplands. The CV of paddy cropland patches increased while fluctuated in  upland cropland. The SI of paddy cropland increased first and then decreased, while that of upland cropland decreased continuously. The mean patch sizes of paddy and upland croplands increased and decreased respectively. The patch density increased in upland cropland while decreased in paddy cropland. The connectivity of upland cropland decreased while that of paddy cropland increased. The staggered degree of both cropland types was enhanced from 2000 to 2013. In general, the paddy agriculture was becoming the dominated agricultural land use mode in the study area while the conversions had different rates in two administrative regions (reclamation and common agricultural areas).

Ecological compensation based on farmers’ willingness: A case study of Jingsan County in Hubei Province, China.

YU Liang-liang, CAI Yin-ying

2015, 26(1):  215-223. 

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Farmland protection is a pressing issue in China’s major agricultural regions because of the strategic importance of these regions for national food security. This study quantified the appropriate ecological compensation criteria for farmland protection by way of estimating farmers’ opportunity cost and willingness to adopt environmentfriendly farming practices. Based on survey data collected from Jingsan County, Hubei Province, a Tobit model was constructed to identify factors affecting farmers’ willingness to accept (WTA). The result showed that with appropriate economic compensation for farmland protection, 77.1% and 64.7% of the surveyed households were willing to reduce usage of fertilizers and pesticides. When the reduced rates of fertilizer and pesticide increased from <10% to >50%, farmers’ opportunity costs of production respectively increased from 1198 and 5850 yuan to 9698 and 9750 yuan per hectare per year, and their WTA increased from 4750 and 7313 yuan to 9781 and 12393 yuan per hectare per year. Farmers’ opportunity cost and WTA in reducing pesticide inputs were larger than those in reducing the same rate of fertilizer inputs, and in each case farmers’ WTA was greater than their opportunity cost. A farm’s distance from township, farmers’ knowledge about the ecology of farmland, and their expectation to improve the ecological environment of farmland had positive, significant effect on the farmers’ WTA to reducing fertilization, while farmers’ education level and the overall economic condition of the village had significantly negative effect. The proportion of agriculture income, farmers’ knowledge about the ecology of farmland, and their expectation to improve the ecological environment of farmland had positive, significant effect on the farmers’ WTA to reducing pesticide, while household’ cash income and the overall economic condition of the village had significantly negative effect.

Predicting the impact of climate change in the next 40 years on the yield of maize in China.

MA Yu-ping1, SUN Lin-li2, E You-hao1, WU Wei3

2015, 26(1):  224-232. 

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Climate change will significantly affect agricultural production in China. The combination of the integral regression model and the latest climate projection may well assess the impact of future climate change on crop yield. In this paper, the correlation model of maize yield and meteorological factors was firstly established for different provinces in China by using the integral regression method, then the impact of climate change in the next 40 years on China’〖KG-*3〗s maize production was evaluated combined the latest climate prediction with the reason be ing analyzed. The results showed that if the current speeds of maize variety improvement and science and technology development were constant, maize yield in China would be mainly in an increasing trend of reduction with time in the next 40 years in a range generally within 5%. Under A2 climate change scenario, the region with the most reduction of maize yield would be the Northeast except during 2021-2030, and the reduction would be generally in the rang〖JP2〗e of 2.3%-4.2%. Maize yield reduction would be also high in the Northwest, Southwest and middle and lower reaches of Yangtze River after 2031. Under B2 scenario,
〖JP〗
the reduction of 5.3% in the Northeast in 2031-2040 would be the greatest across all regions. Other regions with considerable maize yield reduction would be mainly in the Northwest and the Southwest. Reduction in maize yield in North China would be small, generally within 2%, under any scenarios,
and that in South China would be  almost unchanged. The reduction of maize yield in most regions would be greater under A2 scenario than under B2 scenario except for the period of 2021-2030. The effect of the ten day precipitation on maize yield in northern China would be almost positive. However, the effect of ten day average temperature on yield of maize in all regions would be generally negative. The main reason of maize yield reduction was temperature increase in most provinces but precipitation decrease in a few provinces. Assessments of the future change of maize yield in China based on the different methods were not consistent. Further evaluation needs to consider the change of maize variety and scientific and technological progress, and to enhance the reliability of evaluation models.

 

Spatiotemporal dynamics of maize water suitability and assessment of agricultural drought in Liaoning Province, China from 1981 to 2010.

CAI Fu, ZHANG Shu-jie, JI Rui-peng, MI Na, WU Jin-wen, ZHANG Yu-shu

2015, 26(1):  233-240. 

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Maize water suitability (MWS) model was developed at growth stage scale. Frequency and severity of drought were evaluated by combining MWS estimates and agricultural meteorological drought indexes. The MWS at each growth stage was calculated by using maize observational data and conventional meteorological data at 52 sites in Liaoning during the period from 1981 to 2010. Based on the climatic trend and abrupt change analysis, spatiotemporal dynamics of MWS were investigated. Meanwhile, occurrence of agricultural drought and its severity were also estimated. The results showed that the variation of MWS largely differed at different growth stages. Climatic abrupt change happened in 1994, 1996 and 1999 at the stages of emergence to seven leaves (Ⅱ), jointing to tasseling (Ⅳ) and physiological maturity to maturity (Ⅵ). During the past 30 years, MWS showed an obvious increasing trend at the stages of sowing to emergence(Ⅰ), seven leaves to jointing(Ⅲ), Ⅳ and tasseling to physiological maturity(Ⅴ), while it showed a decreasing trend at the stages of Ⅱ and Ⅵ,and that at Ⅵ stage was statistically significant. In addition, the climatic trend of MWS showed apparently spatial variability. The frequencies of drought at different severities varied with maize growth stages. Areas of high variability of MWS were located in the Northwest and South of Liaoning at the stages of Ⅰ, Ⅱ, Ⅲ and Ⅵ, where were also the regions of high frequency of mid and severedrought. At the stages of ⅣandⅤ, the frequency of drought was low and only light and middrought occurred in few areas. In conclusion, the regional mean MWS could be capable to reasonably assess the agricultural drought in Liaoning at the regional scale.

 

Light and temperature indices during the seeding stage of spring maize in Hetao irrigation district, Inner Mongolia, China.

WU Rong-sheng, WU Rui-fen, HOU Qiong, ZHAO Hui-ying, SUN Xiao-long, JIN Lin-xue, CHAO Lu-men

2015, 26(1):  241-248. 

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We collected the experimental dataset of a springmaize in Hetao irrigation district (Bayannaoer, Inner Mongolia) during 2012 and 2013, as well as the crop data observed in related agrometeorological stations to investigate the impacts of light and temperature variation on maize development during the seedling stage to derive adequate light and temperature indices for different suitability. Furthermore, polynomial fitting was applied to interpolate the temperature indices for each day of the whole seedling period to draw the dynamics of the temperature indices and to better characterize its influence on maize development during the seedling stage. The results suggested that the emergence and development rates increased by 11% and 12%, respectively when the average temperature increased 1 ℃ during the sowingemergence period and emergencejointing period, and the biological lowest temperature was 7.4 and 11.9 ℃, respectively. The optimum temperature at the sowingemergence stage ranged from 16.0 to 18.0 ℃, and the leaf area index at the threeleaf stage reached 0.0172 and above. The optimum temperature at the emergencejointing stage ranged from 21.6 to 23.0 ℃, and the photosynthesis/growth of plant tissue was positively correlated with the temperature. The leaf area index in the jointing period could reach 2.15 and the plant height was 120 cm. At the emergencejointing stage, when the sunshine percentage ≥74%, or the daily sunshine hours ≥11.0 h·d^-1, or the total sunshine hours ≥540 h, the dry mass of plant tissue could reach more than 34 g.

 

Impacts of climate warming on growth period and yield of rice  in Northeast China during recent two decades.

HOU Wen-jia, GENG Ting, CHEN Qun, CHEN Chang-qing

2015, 26(1):  249-259. 

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By using rice growth period, yield and climate observation data during the recent two decades, the impact of climate warming on rice  in Northeast China was investigated by mathematical statistics methods. The results indicated that in the three provinces of Northeast China, the average, maximum and minimum temperatures in rice growing season were on the rise, and the rainfall presented a downward trend during 1989-2009. Compared to 1990s, the rice whole growth periods of Heilongjiang, Jilin and Liaoning provinces in 2000s were prolonged 14 d, 4.5 d and 5.1 d, respectively. The increase of temperature in May, June and September could extend the rice growth period, while that in July would shorten the growth duration. The rice growth duration of registered varieties and experiment sites had a similar increasing trend in Northeast China except for the Heilongjiang Province, and the extension of registered varieties growth period was the main factor causing the prolonged growth period of rice at experiment sites. The change in daily average, minimum and maximum temperatures all could affect the rice yield in Northeast China. The increasing temperature significantly increased the rice yield in Heilongjiang Province, especially in the west region of Sanjiang Plain. Except for the south of Liaoning Province, rice yields in other regions of Northeast China were promoted by increasing temperature. Proper measures for breeding, cultivation and farming, could be adopted to fully improve the adaptation of rice to climate warming in Northeast China.

Effect of climate change on rice irrigation water requirement in Songnen Plain, Northeast China.

HUANG Zhi-gang1,2, WANG Xiao-li1, XIAO Ye1, YANG Fei3, WANG Chen-xi1

2015, 26(1):  260-268. 

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Based on meteorological data from China national weather stations and climate scenario grid data through regional climate model provided by National Climate Center, rice water requirement was calculated by using McCloud model and PenmanMonteith model combined with crop coefficient approach. Then the rice irrigation water requirement was estimated by water balance model, and the changes of rice water requirement were analyzed. The results indicated that either in historical period or in climate scenario, rice irrigation water requirement contour lines during the whole growth period and L_mid period decreased along southwest to northeast, and the same irrigation water requirement contour line moved north with decade alternation. Rice irrigation water requirement during the whole growth period increased fluctuantly with decade alternation at 44.2 mm·10 a^-1 in historical period and 19.9 mm·10 a^-1 in climate scenario. The increase in rice irrigation water requirement during the L_mid period with decade alternation was significant in historical period, but not significant in climate scenario. Contribution rate of climate change to rice irrigation water requirement would be fluctuantly increased with decade alternation in climate scenario. Compared with 1970s, contribution rates of climate change to rice irrigation water requirement were 23.6% in 2000s and 34.4% in 2040s, which increased 14.8×10⁸ m³ irrigation water in 2000s and would increase 21.2×10⁸ m³ irrigation water in 2040s.


 

Change characteristics of agricultural climate resources in recent 50 years in Shandong Province, China.

DONG Xu-guang1, LI Sheng-li2, SHI Zhen-bin3, QIU Can1

2015, 26(1):  269-277. 

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Based on the 1961-2010 ground surface data from 90 meteorological stations, this paper analyzed the spatiotemporal change characteristics of agricultural climate resources (e.g. sunshine hours, thermal resources and water) for the growth season of winter wheat and summer maize in Shandong Province. Results indicated that temperature indicators showed a significant rising tendency especially in the winter wheat growth season. Both evapotranspiration and sunshine hours declined obviously, especially for the evapotranspiration in the summer maize growth season, while there was no clear change evidence in rainfall and aridity. Regarding the spatial distribution characteristics, agroclimatic resources presented meridional or zonal increment or decrement in the winter wheat and summer maize growth seasons. In different areas, variation features of agroclimatic resources appeared with distinct differences. In the western Shandong area, temperature indicators showed a slight rising tendency while evapotranspiration and aridity declined significantly. Sunshine hours decreased most significantly in the middle and west southern areas. Precipitation increment was relatively obvious in the winter wheat growth season in the middle and east southern areas and in the summer maize growth season in the middle and southern areas. Thermal resource increases benefited the growth of winter wheat in every phase during the growth period. However, it brought high risks of plant diseases and hot disaster as well. The decrease of sunshine hours was adverse to crop photosynthesis in the growth period while evapotranspiration decrement profited the water retention of soil.

 

Agricultural climate regionalization of dryland farming for potato in Yinshan based on GIS.

MIAO Bai-ling1,2, HOU Qiong2, LIANG Cun-zhu1

2015, 26(1):  278-282. 

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Based on the meteorology dataset of 34 stations over the Yinshan area through the recent 30 years (1982-2010), we investigated the key environmental variables influencing potato yield using the correlation and regression methods. Two environmental variables, including the mean temperature difference, precipitation during the growing season, were selected as the major indexes for determining the suitable area for planting potato. Using the GISbased small grid calculation model, we interpolated these two major environmental variables and produced the climatic map for potato in Yinshan area．The results showed the high potato yield area located in Qianshan and southern Houshan, and the mediumyield division was mainly concentrated in the central Houshan and northwest Qianshan, the lowyield division was distributed mainly in northern Yinshan. Moreover, this study examined the spatial patterns of potato production, and evaluated the stability of potato yield by combining the relative variability of potato yield. This study could provide valuable references for planting potato in Yinshan area.

 

Nitrogen and water cycling of typical cropland in the North China Plain. 

PEI Hong-wei1,2, SHEN Yan-jun1, LIU Chang-ming1

2015, 26(1):  283-296. 

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Intensive fertilization and irrigation associated increasing grain production has led to serious groundwater depletion and soil/water pollution in the North China Plain (NCP). Intensive agriculture changes the initial mass and energy balance, and also results in huge risks to the water/soil resources and food security regionally. Based on the research reports on the nitrogen cycle and water cycle in typical cropland (winter wheat and summer corn) in the NCP during the past 20 years, and the meteorological data, field experiments and surveys, we calculated the nitrogen cycle and water cycle for this typical cropland. Annual total nitrogen input were  632 kg N·hm^-2, including 523 kg N·hm^-2 from commercial fertilizer, 74 kg N·hm^-2 from manure, 23 kg N·hm^-2 from atmosphere, and 12 kg N·hm^-2 from irrigation. All of annual outputs summed to 532 kg N·hm^-2, including 289 kg N·hm^-2 for crop, 77 kg N·hm^-2 staying in soil profile, leaching 104 kg N·hm^-2, 52 kg N·hm^-2 for ammonia volatilization, 10 kg N·hm^-2 loss in nitrification and denitrification. Uncertainties of the individual cases and the  summary process lead to the unbalance of nitrogen. For the dominant parts of the field water cycle, annual precipitation was 557 mm, irrigation was 340 mm, while 762 mm was for evapotranspiration and 135 mm was for deep percolation. Considering uncertainties in the nitrogen and water cycles, coupled experiments based on multidisciplines would be useful for understanding mechanisms for nitrogen and water transfer processes in the soilplantatmospherecontinuum (SPAC), and the interaction between nitrogen and water, as well as determining the critical threshold values for sustainability of soil and water resources in the NCP.

Evaluation indices of greenhouse gas mitigation technologies in cropland ecosystem.

LI Jian-zheng, WANG Ying-chun, WANG Li-gang, LI Hu, QIU Jian-jun, WANG Dao-long

2015, 26(1):  297-303. 

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In spite of the increasing studies on greenhouse gas (GHG) emissions mitigation technologies, there is still a lack of systematic indices for evaluation of their overall impacts in croplands. In this study, we collected all the indices relating to greenhouse gas emissions and analyzed each index following the principles of representativeness, objectivity, completeness, dominance and operability. Finally, we proposed evaluation indices for mitigation technologies based on the current situation of China. Crop yield per unit area was proposed as a constrained index, and greenhouse gas emissions intensity, defined as GHG emissions per unit of produced yield, was proposed as comprehensive index to evaluate the greenhouse effect of various croplands mitigation technologies. Calculation of GHG emissions intensity involved yield, change of soil organic carbon, direct N₂O emissions, paddy CH₄ emissions and direct and indirect emissions from inputs into croplands. By following these evaluation indices, the greenhouse effect of the technologies could be well evaluated, which could provide scientific basis for their further adoption.

Effects of biochar on soil nutrients leaching and potential mechanisms: A review.

LIU Yu-xue1,2, LYU Hao-hao1,2, SHI Yan1,3, WANG Yao-feng1, ZHONG Zhe-ke2,4, YANG Sheng-mao1,2

2015, 26(1):  304-310. 

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Controlling soil nutrient leaching in farmland ecosystems has been a hotspot in the research field of agricultural environment. Biochar has its unique physical and chemical properties, playing a significant role in enhancing soil carbon storage, improving soil quality and increasing crop yield. As a kind of new exogenous material, biochar has the potential in impacting soil nutrient cycling directly or indirectly, and has profound influences on soil nutrient leaching. This paper analyzed the intrinsic factors affecting how biochar affects soil nutrient leaching, such as the physical and chemical properties of biochar, and the interaction between biochar and soil organisms. Then the latest literatures regarding the external factors, including biochar application rates, soil types, depth of soil layer, fertilization conditions and temporal dynamics, through which biochar influences soil nutrient (especially nitrogen and phosphorus) leaching were reviewed. On that basis, four related action mechanisms were clarified, including direct adsorption of nutrients by biochar due to its micropore structure or surface charge, influencing nutrient leaching through increasing soil waterholding capacity, influencing nutrient cycling through the interaction with soil microbes, and preferential transport of absorbed nutrients by fine biochar particles. At last future research directions for better understanding the interactions between biochar and nutrient leaching in the soil were proposed.

 

Characteristics of arbuscular mycorrhizal fungal diversity and functions in salinealkali land.

YANG Hai-xia1,2, GUO Shao-xia1,2, LIU Run-jin1

2015, 26(1):  311-320. 

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Arbuscular mycorrhizal (AM) fungi, widely distributing in various terrestrial ecosystems, are one of the important functional biotic components in soil habitats and play a vital role in improving soil evolution, maintaining soil health and sustainable productivity. Saline-alkali soil is a special habitat affecting plant growth and grain yield. Under the influence of a series of factors, such as human activities on the nature, S and N deposition, ozone, greenhouse effect, climate anomalies, and alien species invasions etc., soil salinization, biodiversity and functions of saline farmlands may be greatly affected, which could consequently influence agricultural production and the sustainable development of ecosystems. Followed by an introduction of the changing characteristics of saline soil area and the secondary salinization under the background of global changes, the present review mainly discussed the changing features of diversity and functions of AM fungi in saline habitats, summarized the factors influencing AM fungal diversity and functions, and the factors’ changing characters under the global changes, in order to provide new ideas and ways in further elucidating the position, role and function of AM fungi in saline soil, and in strengthening saline farmland remediation in response to global changes.

 

Optimal allocation of irrigation water resources based on systematical strategy.

CHENG Shuai1,2, ZHANG Shu-qing1

2015, 26(1):  321-330. 

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With the development of the society and economy, as well as the rapid increase of population, more and more water is needed by human, which intensified the shortage of water resources. The scarcity of water resources and growing competition of water in different water use sectors reduce water availability for irrigation, so it is significant to plan and manage irrigation water resources scientifically and reasonably for improving water use efficiency (WUE) and ensuring food security. Many investigations indicate that WUE can be increased by optimization of water use. However, present studies focused primarily on a particular aspect or scale, which lack systematic analysis on the problem of irrigation water allocation. By summarizing previous related studies, especially those based on intelligent algorithms, this article proposed a multilevel, multiscale framework for allocating irrigation water, and illustrated the basic theory of each component of the framework. Systematical strategy of optimal irrigation water allocation can not only control the total volume of irrigation water on the time scale, but also reduce water loss on the spatial scale. It could provide scientific basis and technical support for improving the irrigation water management level and ensuring the food security.