秸秆不同还田方式对土壤低吸力段持水能力及蒸发特性的影响

利用张力计测定蒸发过程中低吸力段土壤水分特征曲线,对比研究了秸秆在经过粉碎、氨化及与无机土壤改良剂混合三种措施处理后对土壤饱和含水量、低吸力段土壤持水及供水能力和早期干旱过程中土壤脱水速度的影响。结果显示:粉碎秸秆施入土壤后提高了土壤饱和含水量、持水及供水能力,而长秸秆对土壤饱和含水量、持水及供水能力的影响较小;粉碎并氨化的秸秆对土壤饱和含水量、持水及供水能力的提高作用更为显著。粉碎秸秆及长秸秆处理均易造成早期干旱过程中脱水速度过快,氨化后或当秸秆与无机土壤改良剂混合施入土壤时,土壤低吸力段脱水速度明显减慢,利于土壤有效水的保存。该结果为提出新的能最大效率发挥秸秆改良土壤作用的秸秆还田方式提供了一定的理论基础。

Effect of different straw-incorporation methods on soil water retention capacity and evaporation

Soil water retention curves in low suction range during the evaporation process were determined by use of tensiometers to study the effects of three straw treating manners (i.e. cut, aminated or mixed with inorganic soil amendment) on saturated soil water content, soil water retention and supply capacities as well as the soil dehydration rate in the early stage of drought process. Results show that incorporation of finely cut straws into soil enhanced saturated soil water content, improving soil water retention and supply capacities, and the finely cut and aminated straws were more effective than the long cut straws. The dehydration rate of the soil in the early stage of drought in low suction range increased when the straws (both finely cut or long cut) were applied in soil, while decreased with the aminated straws or straws mixed with inorganic soil amendment, and more soil available water conserved. The results provide useful information for more efficient straw-incorporation method to improve the soil water retention capacity.