Effect Of Different Irrigation Methods On Soil Organic Carbon Components In Protected Field

The green house experiment of different irrigation methods includes furrow irrigation, drip irrigation and subsurface irrigation was conducted for a long term, and determined ratio of soil respiration and effects on various enzymes. This greenhouse experiment finished in the same program, in the same block for 10 consecutive years on water-saving irrigation. The main results are follows:(1) the content of soil total organic carbon,,total nitrogen,C/N,and components of organic carbon were all showed the biggest amount in the soil surface and their content increased with layers'depth.(2) There were significant differences within irrigation methods. Soil total organic carbon content in 0-10 cm and 80-100 cm soil layers were furrow irrigation>subsurface irrigation>drip irrigation and in 10-80 cm soil layers was subsurface irrigation>furrow irrigation>drip irrigation. In 0-100cm profile layers, DOC content showed furrow irrigation>drip irrigation>subsurface irrigation. MBC content showed drip irrigation> furrow irrigation>subsurface irrigation. ROC showed drip irrigation>subsurface irrigation >furrow irrigation.POC showed furrow irrigation>subsurface irrigation>drip irrigation.LOC content in 0-10 cm and 80-100 cm soil layers were furrow irrigation> subsurface irrigation>drip irrigation and in 10-80 cm soil layers was subsurface irrigation >furrow irrigation>drip irrigation.The content of SHC and H/F in 0-20cm showed subsurface irrigation>drip irrigation>furrow irrigation.20-60cm showed furrow irrigation >subsurface irrigation>drip irrigation,and in 60-100cm showed furrow irrigation>drip irrigation>subsurface irrigation.(3) The content of DOC,MBC, ROC,LOC,POC accounted for 4.98%-12.87%,1.48%-2.82%,17.32%-75.07%,50.52%-54.91%,18.46%-47.88%,31.83%-57.07% of the total organic carbon, respectively. In 0-100cm profile layers, the distribution of DOC and MBC accounted for the proportion of total organic carbon were all showed drip irrigation>furrow irrigation>subsurface irrigation,ROC showed drip irrigation> subsurface irrigation>furrow irrigation, POC showed furrow irrigation>drip irrigation> subsurface irrigation.SHC in 0-20cm showed subsurface irrigation>drip irrigation> furrow irrigation,and in 20-100cm showed furrow irrigation>drip irrigation>subsurface irrigation.(4) DOC, MBC, LOC, POC, SHC and soil total organic carbon content of a significant positive correlation.Summarize, Furrow irrigation facilitated the accumulation of TOC, DOC, POC and SHC while drip irrigation increased the MBC and ROC; The most unfavorable accumulation for soil organic carbon is subsurface irrigator.The content of TOC and the ratios of active organic carbon to TOC was the lowest in subsurface irrigation.Therefore, comprehensively considered from agricultural water conservation, improve soil organic carbon storage and utilization of active organic carbon, drip irrigation is the best irrigation method in protection soil.