秸秆还田深度对春玉米农田土壤有机碳、氮含量和土壤酶活性的影响

Effects of straw return depth on soil organic carbon, nitrogen content, and soil enzyme activity of spring maize field

为研究秸秆还田旋耕深度对土壤理化性质和酶活性的影响,明确不同秸秆还田深度条件下土壤理化性质与酶活性的关系,在3年(2016—2018年)田间微区定位试验条件下,研究秸秆旋耕还田10 cm(S1D1)、20 cm(S1D2)、30 cm(S1D3)和秸秆移除旋耕10 cm(S2D1)、20 cm(S2D2)、30 cm(S2D3)6个处理对东北春玉米农田土壤理化性质和酶活性的影响。结果表明:旋耕深度(D)及其与秸秆处理(S)交互作用(S×D)显著影响土壤有机碳(SOC)含量,0~20 cm土层S1D1、S1D2处理SOC含量较S1D3处理高1.2%~16.0%,而20~40 cm土层S2D3处理SOC含量最高。旋耕深度、秸秆处理及两者交互作用对土壤硝态氮(NO-3-N)和铵态氮(NH+4-N)含量、蔗糖酶和过氧化氢酶活性影响显著。在0~40 cm土层,D1、D2旋耕深度下秸秆还田处理NO-3-N含量比秸秆移除处理平均提高46.9%和34.9%,NH+4-N含量平均降低31.6%和4.4%。在各旋耕深度下,S1处理0~20 cm土层蔗糖酶和脲酶活性高于S2处理,20~30 cm土层过氧化氢酶活性低于S2处理。相关性分析表明,SOC、土壤全氮(TN)与NO-3-N、NH+4-N含量和蔗糖酶活性呈显著正相关,与pH、土壤含水量(SWC)呈显著负相关。主成分分析表明,与S1D1相比,S1D2对0~20土层蔗糖酶、脲酶、过氧化氢酶活性和0~40 cm土层SOC、TN含量影响更明显。综上所述,秸秆旋耕还田20 cm可改善0~40 cm土层养分水平,提高土壤酶活性,推荐为东北春玉米产区农田土壤培肥的合理秸秆还田方式。

This study aimed to determine the effect of straw return depth on soil physicochemical properties,enzyme activity,and the relationship between them under different straw return depths.A field micro-plots experiment was conducted for 3-year(2016-2018)in northeast China,and totally six treatments were set as following:straw incorporation with rotary tillage for 10 cm(S1D1),20 cm(S1D2)and 30 cm(S1D3)of soil depth,and straw removal with rotary tillage in the same soil depth(S2D1,S2D2 and S2D3),respectively.Individual and interaction effects on physical and chemical properties of soil and enzyme activity of spring maize field were determined in this study.Results indicated that the soil organic carbon(SOC)was significantly affected by rotary tillage depth(D)and its interaction with straw(S)treatment(P<0.05).SOC contents under S1D1 and S1D2 were 1.2%~16.0%,respectively,higher than those under S1D3 treatment at 0~20 cm soil layer,and the highest SOC content at 20~40 cm soil layer was observed in S2D3 treatment.Soil nitrate(NO-3-N)and ammonium(NH+4-N)contents and invertase and catalase activities were significantly influenced by straw and rotary tillage depth treatments and their interactions(P<0.05).Across 0~40 cm soil layer,S1 treatment increased soil NO-3-N contents under D1 and D2 conditions by an average of 46.9%and 34.9%,respectively,but lowered soil NH+4-N contents by an average of 31.6%and 4.4%,respectively,compared with S2 treatment.Among treatments of rotary tillage depth,S1 treatment enhanced soil invertase and urease activities at 0~20 cm layer and decreased catalase activity at 20~30 cm layer,compared with S2 treatment.Correlation analysis revealed that SOC,soil TN,NO-3-N and NH4+-N content,and invertase activity were significantly positive correlated.Both SOC and TN were highly negatively correlated with soil pH and soil water content(SWC).Principal component analysis(PCA)suggested that SOC,TN content and enzymes activity were more obviously affected by S1D2 treatment in 0~40 cm and 0~20 cm soil layer,respectively,compared with S1D1 treatment.Overall,soil nutrients level and enzymes activity at 0~40 cm layer were improved by S1D2 treatment,and might be considered as a suitable straw incorporation method for improving soil fertility in maize field within the study area.