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Soil respiration dynamics in sugarcane cropland under different irrigation modes.

TAN Juan*   

  1. (Shanghai Academy of Environmental Sciences, Shanghai 200233, China).
  • Online:2017-12-10 Published:2017-12-10

Abstract: In order to investigate the effects of different irrigation modes on soil respiration in cropland of sugarcane cultivar Liucheng 05-136, five types of irrigation, including subsurface drip irrigation (SSDI), surface drip irrigation (SDI), pipe irrigation (PI), sprinkler irrigation (SI), and microsprinkler irrigation (MSI), were employed. Field measurements of soil respiration rate and related environmental factors (soil temperature and soil water content) were conducted at five growth phases (tillering; early, peak, and late elongation; and maturity) at the Sugarcane Efficient Watersaving Irrigation Test Base in Chongzuo City of Guangxi from March to December in 2015. Soil respiration rates in different treatments showed similar seasonal variability. Seasonal mean soil respiration rate was lowest in the MSI mode (2.59 μmol·m-2·s-1) and highest in the PI mode (4.50 μmol·m-2·s-1). Soil respiration in the PI mode was 61.59%, 27.61%, 15.97% and 12.33% higher than that in the MSI, SSDI, SDI and SI modes, respectively (P<0.01), which indicated that PI irrigation can enhance sugarcane soil respiration rate. The relationship between soil respiration and soil temperature was well explained by exponential functions. Correlations between respiration and temperature were highly significant (P<0.01) under SSDI, SDI, PI and SI modes, and significant under the MSI mode (P<0.05). While the relationship between soil respiration and soil water content could be described with a quadratic function, the correlation was significant only under the PI mode (P<0.05). In comparison to single-factor equation, two-factor equations better predicted soil respiration rate, with coefficients being highly significant (P<0.01, R2=0.41-0.83). The temperature sensitivity coefficient (Q10) of soil respiration was 1.98-2.50. Pipe irrigation was the most temperature sensitive mode, while the least sensitive was the SI mode. These findings provide reference for more comprehensive evaluation of the ecological and environment effects of sugarcane water-saving irrigation practices, for accurately assessing the carbon source/sink features of sugarcane cropland ecosystems.

Key words: spatial resolution, multispectral remote sensing, scale effect., tree species classification, texture information