太湖地区集约化农田氮素减排增效技术实践

The practice of technologies for nitrogen emission reduction and efficiency increase in intensive farmland of Tai Lake region

通过开展氮高效水稻品种种植与化肥减施的增效减排技术、稻田生物炭应用增效减排技术、固氮作物养分减投与轮作制度调整技术、菜地机械起垄侧条施肥技术等的研发和适地性研究,优化了技术参数,明确了技术效果:氮高效水稻品种生产单位产量谷物时稻田NH_3挥发量比常规水稻品种下降17.4%~27.3%(平均为21.3%),稻田氮素渗漏损失量下降6.08%~44.0%(平均为25.3%),稻田氮素径流损失量下降9.18%~28.7%;与单施尿素相比,稻田中施用0.5%(表层土壤质量百分比)的低温(500℃)制备生物炭,维持水稻高产且不增加单位产量氨挥发损失的同时,可显著减少土壤氮素径流损失13.9%~22.1%;传统的集约化蔬菜轮作中引入豆科作物金花菜,可减少周年总氮淋失约40%,并且可使经济效益提高29%;大白菜机械起垄侧条施肥的适宜垄宽为55cm,在保证高产的同时,可减施化肥氮约30%,节本增效58.3%,并且减少50%以上的氨挥发。以上技术在集约化农田上的实践,有力地推动了国家化肥零增长战略和太湖地区农田面源污染防治。

In Tai Lake region, we conducted serial experiments to evaluate the efficiencies of following technologies including plantation of rice with high NUE, incorporation of biochar, optimization the rotation system with nitrogen fixing crops, and mechanical ridging and sidestrip fertilization in vegetable fields, to improve nitrogen use efficiency and mitigate nitrogen losses to the water and atmosphere. Especially, we optimized the related technical parameters and clarified the efficiencies of each technology. The results suggested that ： High nitrogen use effieiency（high-NUE） rice cuhivars produced 17.4%～27.3% （21.3% on average） less amounts of NH3 volatilization from paddy field, 6.08%～44.0% （25.3% on average） less N losses by soil leaching, and 9.18%～28.7% less N losses through runoff on a yield-scaled basis than the conventional cuhivar. Compared with urea input alone, application of biochar pyrolyzed under a relative low temperature （500 ℃ ） and at a relative low rate（0.5% wt） can guarantee rice grain yield and significantly reduced（P〈0.05） the runoff N losses by 13.9%～22.1%, without increases of yield-scale NH3 losses. Optimization the vegetable rotation system with nitrogen fixing crop california bur clover （Medicago hispida Gaertn L.） reduced annual total N leaching losses by approximately 40.0% and increase the economic benefit by approximately by 29.0%. The appropriate width of ridge is 55 cm for mechanical ridging in cabbage plantation. Strip fertilization reduced about 30% N fertilizer, which saving the cost and increasing the efficiency by 58.3%. Moreover, this technology mitigated the NH3 volatilization by more than 50%. The practices of aforementioned technologies in intensive farmland effectively promote the China national strategy of ＂Zero growth of chemical fertilizer use＂ and the control of non-point source pollution in Tai Lake region.