秸秆配施氮肥还田对水稻土酶活性的影响

通过田间试验研究秸秆还田时间及配施氮肥比例对水稻土酶活性的影响,以期为培育水稻土肥力和稳定稻田生态系统功能提供理论依据。试验设置2个秸秆还田时间(WS,冬季还田;SS,春季还田)和4个氮肥配施量(N0,秸秆还田,试验期内全程不添加矿质氮;NB,常规施肥,还田时不添加矿质氮;N30B,秸秆还田时添加早稻基肥用量的30%矿质氮;N60B,秸秆还田时添加早稻基肥用量的60%矿质氮)。研究结果表明:1冬季秸秆翻耕还田能增加冬闲期6种与土壤碳周转相关酶(β-葡萄糖苷酶、β-纤维二糖苷酶、β-木糖苷酶、多酚氧化酶、过氧化物酶和蔗糖酶)的活性,冬闲期冬季秸秆还田条件下土壤酶活性均高于春季还田,生育期内冬季秸秆翻耕还田措施对土壤β-葡糖苷酶和过氧化物酶有增加作用;2秸秆还田并配施氮肥措施显著地增加冬闲期和生育期β-纤维二糖苷酶的活性,但配施氮肥的3个比例间土壤酶活性并无显著差异;3除多酚氧化酶外,其他5种酶均与其有机碳投入量呈显著正相关。因此,冬季秸秆还田及配施氮肥能在一定程度上调控与碳周转相关的土壤酶活性,对推广冬闲期秸秆翻耕还田及保障作物的产量具有重要的生态学意义。

Effects of Rice Straw Returning Timing Combined with Nitrogen Fertilization on Enzyme Activities of Paddy Soil

A field experiment was conducted to study the effects of straw returning timing combined with nitrogen (N) fertilizer application ratio on enzyme activities in paddy soil in order to provide theoretical basis for fostering soil fertility and stabilizing paddy field ecosystem function. The experiment consisted of two rice straw returning times (WS: returning in winter;SS: returning in spring) and four N fertilizer application levels (N0, straw returning and no N fertilization during all the experimental course; NB, conventional fertilization, and no N fertilization when straw returning; N30B, 30% N of base fertilizer applied when straw returning; N60B, 60% N of base fertilizer applied when straw returning). The results showed that: 1) Straw returning in winter increased the activities of six soil enzymes (β-Glucosidase,β-Cellobiosidase,β-Xylosidase, Phenol oxidase, Peroxidase and Invertase) related to C turnover. In winter fallow period, enzyme activities were higher at winter straw returning than those at spring straw returning, and winter straw returning increased both the activities ofβ-Glucosidase and Peroxidase during early-rice growth stage. 2) Rice straw returning combined with N fertilization application significantly increasedβ-cellobiosidase activity both in winter fallow period and in early-rice growth stage, but there was no significant difference in soil enzyme activities under the three levels of N fertilizer application. 3) All the enzyme activities, except Phenol oxidase, had significantly positive correlations with organic C inputs. Therefore, rice straw returning combined with N fertilizer application in winter can regulate soil enzyme activities related to C turnover to some extent, which has ecological significance to promoting straw returning in winter and ensuring the crop yield.