肥沃耕层构建对东北黑土区旱地土壤肥力和玉米产量的影响

有机物料还田是提高土壤肥力、改善土壤结构和增加作物产量的重要农艺措施之一。本研究通过分析有机物料深混还田构建肥沃耕层后土壤的有机质、速效养分含量和玉米产量,明确了黑土区不同土壤类型旱地土壤肥力指标和玉米产量对肥沃耕层构建方式的响应特征,以期为实现东北黑土区旱地保护性利用和农业可持续发展提供科学依据。采用小区试验与大区示范相结合的方式,在黑龙江省、吉林省和辽宁省选取9个生态类型区作为试验点,土壤类型包括黑土(中厚黑土和薄层黑土)、草甸土、黑钙土、白浆土、棕壤、暗棕壤和褐土。每个试验点均设置了玉米秸秆深混构建肥沃耕层(CF_Ⅰ)、秸秆配合有机肥深混构建肥沃耕层(CF_Ⅱ)和无有机物料还田(CK)3个处理。其中,CF_Ⅰ、CF_Ⅱ处理的小区试验和大区示范的秸秆还田量分别为10000 kg·hm^-2和全量还田,CF_Ⅱ处理的有机肥施用量为30000 t·hm^-2;CF_Ⅰ和CF_Ⅱ处理中有机物料的还田深度均为0~35 cm。结果表明: 不同土壤类型旱地的土壤肥力差异较大,不同土层表现为亚耕层土壤肥力小于耕层土壤,其中暗棕壤和白浆土尤为突出;棕壤、褐土耕层和亚耕层的土壤肥力均偏低;黑土和草甸土的质地比较黏重和犁底层较厚。在试验时间为两年以上的5个试验点中,与CK相比,CF_Ⅰ和CF_Ⅱ处理耕层的土壤有机质、碱解氮、速效磷和速效钾含量平均增加1.85 g·kg^-1、20.16 mg·kg^-1、1.56 mg·kg^-1和17.2 mg·kg^-1,亚耕层较耕层增加了2.09 g·kg^-1、12.06 mg·kg^-1、2.18 mg·kg^-1和3.84 mg·kg^-1。与CK相比,CF_Ⅰ处理显著增加了耕作层和亚耕层土壤有机质和速效磷含量,CF_Ⅱ处理显著增加了耕作层和亚耕层的全部土壤肥力指标,说明肥沃耕层构建是提高土壤肥力的重要途径,其中玉米秸秆配施有机肥是快速提升土壤肥力的有效方法。受不同地区水热条件和土壤类型等的影响,不同试验区的玉米产量差异较大;不同处理间差异显著,表现为CF_Ⅱ>CF_Ⅰ>CK,说明肥沃耕层构建方式在不同生态类型区均能有效提高玉米产量。采用玉米秸秆或者玉米秸秆配合有机肥深混的肥沃耕层构建方式能够同步培肥耕层和亚耕层土壤,提高玉米产量。不同生态类型区应根据土壤类型、有机物料来源等采取相应的肥沃耕层构建方式,建议在有机肥源充足的区域,优先采用秸秆配合有机肥深混构建肥沃耕层。

Effects of the construction of fertile and cultivated upland soil layer on soil fertility and maize yield in black soil region in Northeast China.

Organic amendment return could enhance soil fertility, improve soil structure, and increase crop yield. However, how construction of soil layers can affect soil fertility and crop yield are not fully understood. We examined the effects of constructions of fertile and cultivated soil layer on soil fertility and maize yield in the upland black soil region in Northeast China, to provide theoretical guidance in increasing soil fertility and sustainable development of agriculture. Based on the combination of field plot experiments and demonstration regions, nine study sites with different ecological characteristics were selected from Heilongjiang, Jilin and Liaoning provinces from northeast China, covering dark brown, black, meadow, chernozem, albic, brown and cinnamon soils. There were three treatments in each study site, including maize straw return within 0-35 cm soil layer (CF_Ⅰ), the combination of maize straw and organic manure return within 0-35 cm soil layer (CF_Ⅱ) and conventional agricultural practice without organic amendmentas control (CK). The rate of straw return in CF_Ⅰ and CF_Ⅱ treatments were 10000 kg·hm^-2, and full straw for demonstration regions. The rate of organic manure in CF_Ⅱ treatment was 30000 kg·hm^-2. Considerable difference in soil fertility were recorded among the nine study sites with the trend of tillage layer > sub-tillage layer, especially for dark brown soil and albic soil. Soil fertility of tillage layer and sub-tillage layer was relatively low both for brown soil and cinnamon soil. The heavy clay and plow pan were pivotal limiting factors of soil fertility for the black soil and the meadow soil. Compared with CK, the concentrations of soil organic matter (SOM), available nitrogen (AN), available phosphorous (AP), and available potassium (AK) in tillage layers was increased on average by 1.85 g·kg^-1, 20.16 mg·kg^-1, 1.56 mg·kg^-1 and 17.2 mg·kg^-1 in the CF_Ⅰ and CF_Ⅱ treatments in five study sites with more than two years of treatments. The contents of SOM, AN, AP and AK in sub-tillage layer increased by 2.09 g·kg^-1, 12.06 mg·kg^-1, 2.18 mg·kg^-1 and 3.84 mg·kg^-1, compared with tillage layer. CF_Ⅰ treatment significantly enhanced the contents of SOM and AP in both tested soil layers, while CF_Ⅱ treatment significantly enhanced all fertility indices in both tested soil layers. This indicated that the increase of organic amendment return is an effective way to improve soil fertility. Maize yield fluctuated under the combined effect of climatic conditions and soil types. The significant differences in maize yield under CK, CF_Ⅰ and CF_Ⅱ treatments were observed with a trend of CF_Ⅱ > CF_Ⅰ > CK. This result indicated that the construction of fertile and cultivated soil layer could significantly increase maize yield independent of soil types. The construction of fertile and cultivated soil layer based on maize straw return or maize straw and organic manure combined return within 0-35 cm soil layer, could simultaneously increase soil fertility in both tillage and sub-tillage layer, as well as maize yield. We suggested that the selection of approaches of the constructions of fertile and cultivated soil layer should consider soil types and the sources of organic amendments. It should also give priority to soil layers rich in organic manure source to construct fertile and cultivated soil layers.