不同类型养殖粪水施用对青贮玉米种植土壤肥力、氮素平衡和经济效益的影响

Impact of applicaiton of different types of livestock wastewater on soil fertility, nitrogen balance, and economic benefits of silage corn

  • 摘要: 养殖粪水的处理和利用是制约我国养殖业绿色可持续发展的痛点和难点。养殖粪水由之前的“多工序、长链条”达标排放逐步转向“适度处理, 农田回用”, 但其处理程度对养殖粪水养分特性具有较大影响, 不同类型养殖粪水对作物产量及其施用的经济效益尚不清楚。本研究选取了集约化奶牛养殖场粪水处理过程不同环节产生的不同类型粪水作为试验对象, 研究了粪尿混合物、沼液混合物、AO (anoxic-oxic)出水和氧化塘沼液及其不同还田量对作物产量、土壤地力和经济效益的影响。粪尿混合物、沼液混合物和AO出水的养分含量较高, 可用作有机肥, 分别按照50%和100%等氮替代施用; 氧化塘沼液养分含量较低, 作为灌溉水施用。结果表明, 粪水50%等氮替代处理T2和T3可使作物产量平均提高12.24%, 其中AO出水50%等氮替代处理下作物产量最高; 而粪水100%等氮替代处理则存在减产风险。粪尿混合物施用可以提升土壤地力, 粪水100%等氮替代处理土壤全氮和有机质含量总体高于粪水50%等氮替代处理。相同替代比例的前提下, 粪水50%等氮替代处理还田成本约12.5~13.5 ¥·t−1, 粪水100%等氮替代处理还田成本为5.0~7.0 ¥·t−1; 结合作物产量和农产品售价, 沼液混合物50%等氮替代处理经济效益最好, 可达38.3 ¥·t−1。因此, 从经济效益角度出发, 沼液混合物50%等氮替代处理为最优还田策略。

     

    Abstract: The treatment and utilization of livestock wastewater are major challenges in promoting green and sustainable development of the livestock industry in China. The degree of treatment of livestock wastewater, as it transitions from standard discharge to resource utilization, has a substantial impact on its nutrient characteristics. However, the effects of different types of livestock wastewater on crop yield and the economic benefits of their application are not yet fully understood. In this study, various types of livestock wastewater produced at different stages of the treatment process during intensive dairy farming operations were selected. We investigated the effects of mixture of manure and urine, digestated pulp, AO (anoxic-oxic) process effluent, and liquid digestate from oxidation pond, as well as the effects of different application rates (50% nitrogen substitution, 100% nitrogen substitution, and irrigation with no nitrogen substitution) on crop yield, soil fertility, and economic returns. The results indicated that T2 and T3 treatments applying livestock wastewater at a 50% nitrogen substitution rate could increase crop yield by an average of 12.24%, whereas the 100% nitrogen substitution treatments posed a risk of yield reduction. Among these, the highest crop yield was observed with a 50% nitrogen equivalent substitution with AO process effluent, suggesting that the partial substitution of chemical nitrogen fertilizer with livestock wastewater can enhance crop productivity under certain conditions. The application of a mixture of manure and urine had a significant positive effect on soil fertility, particularly in terms of increasing the contents of soil total nitrogen and organic matter. Under the 100% nitrogen substitution treatments, soil total nitrogen and organic matter levels were generally higher than those in the 50% substitution treatments. This suggests that 100% nitrogen substitution using livestock wastewater contributes substantially to soil enrichment and can support sustainable soil health over time. In terms of economic costs, applying livestock wastewater at a 50% nitrogen substitution rate incurred a cost of approximately 12.5 to 13.5 ¥·t−1, whereas the 100% nitrogen substitution treatments were more economical, with costs ranging from 5.0 to 7.0 ¥·t−1. However, when considering both crop yield and the market price of agricultural products, the 50% nitrogen equivalent substitution treatment with digestated pulp produced the best economic returns, reaching up to 38.3 ¥·t−1. Thus, from an economic perspective, a 50% nitrogen substitution treatment with digestated pulp is the optimal strategy for field applications. This approach balances the benefits of improved crop yield, enhanced soil fertility, and maximized economic gain, making it a promising method for sustainable agricultural development.

     

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