小麦化肥减施与不同轮作方式的周年养分平衡及经济效益分析

【目的】研究小麦化肥减量条件下不同轮作方式土壤养分平衡及经济效益差异,探索适宜陕西关中小麦玉米轮作区的小麦轮作方式,为减少化肥投入,提高农民经济收入提供思路与科学依据。【方法】于2018—2020年在陕西武功镇开展田间试验,随机区组设计。设玉米-小麦轮作农户施肥（CWF）、玉米-小麦轮作推荐施肥（CWR）、绿肥-小麦轮作推荐施肥（GWR）、大豆-小麦轮作推荐施肥（BWR）4个处理,除农户施肥处理外,其他3个处理的小麦季施肥均采用监控施肥技术推荐施肥。采集不同夏季作物及冬小麦的植物和土壤样品进行分析。【结果】与农户施肥相比,玉米-小麦轮作推荐施肥处理在氮、磷肥分别减量11.8%、41.7% 条件下,显著增加了小麦产量,平均增幅为7.4%,显著增加了小麦籽粒及地上部氮、磷素养分累积量,氮素累积量增幅分别为10.1%、8.9%,磷素累积量增幅分别为9.8%、6.4%;玉米-小麦轮作推荐施肥处理显著降低了土壤氮、磷、钾素盈余率,降幅分别为25.1%、72.3%和54.4%,显著提高经济收益36%。推荐施肥的3种轮作方式中,玉米-小麦轮作小麦产量最高,其次为大豆-小麦轮作。大豆-小麦轮作氮、磷、钾盈余率均显著低于玉米-小麦轮作和绿肥-小麦轮作,降低幅度分别为87.3%—92.0%、41.9%—67.7%、78.1%—85.3%,并获得了最高的经济收益。【结论】监控施肥的推荐施肥方法不仅能够减少化肥投入,降低生产成本,同时能够增加小麦产量,提高小麦籽粒及地上部养分累积量,减少氮、磷养分平衡的盈余率,提高经济收益。相比玉米-小麦轮作方式,大豆-小麦轮作既减少了化肥的投入,大幅降低氮、磷、钾养分盈余量,同时还取得较高的经济效益。综上,陕西关中地区传统的玉米-小麦轮作可通过优化施肥减少化肥投入,降低生产成本;而综合考虑土壤培肥、环境效益与经济收益,优先推荐大豆-小麦轮作方式,减少土壤养分盈余,提高种粮农户的经济收益。

Annual Nutrients Balance and Economic Return Analysis of Wheat with Fertilizers Reduction and Different Rotations

【Objective】The present study aimed to investigate the soil nutrients balance and economic benefits of different rotations with optimal chemical fertilizer application for wheat production, with the purpose of selecting a proper rotation for wheat production with lower fertilizer application and improvement of economic return for local farmers.【Method】The field experiments with randomized block design were carried out in Wugong county from 2018 to 2020, including four treatments: maize-wheat rotation with farmer accustomed fertilization (CWF), maize-wheat rotation with recommended fertilization (CWR), green manure-wheat rotation (GWR), and soybean-wheat rotation (BWR). Except for treatment of CWF, the fertilizers of rest three treatments were calculated according to the method of soil testing and determining fertilizer recommendations (STDFR). The plants tissues and soil with different depth were sampled for nutrients analysis.【Result】Compared with CWF, with 11.8% reduction of nitrogen and 41.7% reduction of phosphorus, the CWR treatment significantly increased wheat yield, with an average increase of 7.4%, and significantly increased the nitrogen and phosphorus uptake of wheat grain and aboveground shoot, with the nitrogen increase of 10.1% and 8.9% respectively, and the phosphorus increase of 9.8% and 6.4%, respectively. CWR treatment decreased the surplus rate of soil N, P and K by 25.1%, 72.3% and 54.4%, respectively, and increased the economic benefit by 36%. Among three different rotation, CWR rotation had the highest wheat yield, followed by soybean wheat rotation and green manure wheat rotation. GWR rotation had the lowest surplus ratio of NPK among three treatment with optimal fertilizer application, which was significantly lower than that of CWR and GWR rotation, with the decrease range of 87.3%-92.0%, 41.9%-67.7%, and 78.1%-85.3%, respectively, and obtained the highest economic return.【Conclusion】Fertilization recommendation by monitoring soil nutrients techniques could not only decrease fertilizer input and production cost, but also increase wheat yield, increase nutrient uptake of wheat grain, reduce surplus rate of nitrogen and phosphorus nutrient balance, and thus improve economic benefits. Compared with maize-wheat rotation, the soybean-wheat rotation not only reduced the input of chemical fertilizer, significantly reduced the surplus of nitrogen, phosphorus and potassium, but also achieved higher economic benefits. In conclusion, it was recommended that the fertilizers application rates should be optimized for maize-wheat rotation in Guanzhong Plain. However, taking into account of economic return and ecological benefit, the soybean-wheat rotation was prior choice for the purpose of decreasing soil nutrients surplus and enhancing the economic return of farmers.