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Effects of irrigation and nitrogen fertilization regulations on soil nitrogen supply potential in greenhouse.

WU Han-qing1,2,3, LI Su-jie1, LIU Yang-yi1, ZHANG Xin-rui1, ZHAO Qi-long1, LI Meng-si1, ZOU Hong-tao1,2,3, DANG Xiu-li1,2,3, ZHANG Yu-ling1,2,3, YU Na1,2,3*   

  1. (1College of Land and Environment, Shenyang Agricultural University, Shenyang 110866, China; 2Key Laboratory of Arable Land Conservation (Northeast China), Ministry of Agriculture and Rural Affairs, Shenyang 110866, China; 3National Engineering Laboratory for Efficient Utilization of Soil and Fertilizer Resources, Shenyang 110866, China).
  • Online:2019-05-10 Published:2019-05-10

Abstract: Soil organic carbon (SOC), total nitrogen (TN), fixed ammonium (FA), microbial biomass nitrogen (SMBN) and organic nitrogen fractions are important indicators of soil nitrogen supply potential. A three-year tomato field experiment with mulchfilm drip irrigation was conducted to investigate the effects of lower irrigation limits (25, 35, and 45 kPa) and nitrogen fertilization levels (75, 300, and 525 kg·N·hm-2) on greenhouse soil N supply potential (including SOC, TN, FA, SMBN and soil organic nitrogen fraction storage). The results showed that the main effects of irrigation and nitrogen fertilization on the storage of SOC and TN were statistically significant, but that was not the case for their interactive effects. The main and interactive effects of irrigation and nitrogen fertilization on the storage of greenhouse soil organic nitrogen fractions, SMBN and FA at 0-30 cm soil layer were significant in the fallow period. Under different treatments of irrigation and nitrogen fertilization regulations, the proportions of acidolysable organic nitrogen fractions in greenhouse soil during the fallow period followed the order: acidoly sable amino acid nitrogen (AAN) > acidolysable ammonium nitrogen (AN) > acidolysable unknown nitrogen (UN) > acidolysable amino sugar nitrogen (ASN). AAN was the major fraction of greenhouse soil organic nitrogen. AAN had a significant positive correlation with AN, ASN, acid hydrolyzed nitrogen (AHN), non-acidrolyzable nitrogen (NAN), SOC and TN. There was a significant positive correlation between FA and AAN. SMBN was positively correlated with ASN and AN, and negatively correlated with AAN. Therefore, AAN, SMBN and FA could be used as indicators for greenhouse soil nitrogen supply potential in a certain extent. Reasonable regulations of irrigation and nitrogen fertilization are conducive to improving greenhouse soil nitrogen supply potential.

Key words: connectivity index, distance model, ecological services value, tidal flat reclamation, urban waterbody.