减量施肥条件下甜玉米产量效应与农田氮、磷流失特征

从农田面源污染产生的源头入手,研究减量施肥条件下甜玉米的产量效应和氮、磷流失特征,寻求防控甜玉米农田氮、磷流失的减肥增效措施。通过田间试验,设置（1）不施肥(CK);（2）常规施肥(CF);（3）配方肥(FF);（4）配方肥+有机肥(OFFF);（5）配方肥+生物炭(BFF);（6）配方肥+控释尿素(CRUFF);（7）尿素+控释BB肥(UCRF)。结果表明：在氮肥用量减少20%条件下,处理CF与FF、BFF、CRUFF之间并无显著差异,而与处理OFFF、UCRF间达到显著差异(P<0.05),OFFF、UCRF分别较CF增产达17.8%、16.8%。甜玉米生育期地表径流总氮浓度和流失量呈逐步下降趋势,CF氮素流失总量最大,达到3.54 kg/hm²;减量施肥条件下农田氮素流失总量显著降低,降幅为18.4%~45.5%,其中以CRUFF最为显著,其次为UCRF、OFFF和BFF;减量施肥条件下,OFFF、FF、UCRF处理总磷流失量显著降低(P<0.05),降幅为46.7%~60.0%,其中以OFFF最为显著。浅层地下水氮磷浓度能一定程度反映农田氮磷渗漏情况。甜玉米生育期CF处理浅层地下水氮磷浓度最高,分别达到45.85 mg/L和4.10 mg/L,而CRUFF生育期总氮浓度最高为22.79 mg/L,较CF降低50.3%,CRUFF生育期总磷浓度最高为2.73 mg/L,较CF降低33.4%。浅层地下水中氮素是以铵态氮为主要存在形态。与传统施肥比较,以减氮20%为目标的配方肥(21.2-6.36-18.42)及其分别与控释尿素、控释BB肥、有机肥配施不仅可以获得高产,而且能有效防控农田氮磷流失,减少面源污染风险。

Yield Effect of Sweet Corn and Characteristics of Farmland Nitrogen and Phosphorus Runoff Losses Under Reduced Fertilizer Rate

Starting from the source of farmland non-point source pollution, the yield effect of sweet corn (Zea mays) and nitrogen and phosphorus runoff losses from farmland under reduced fertilizer rate were studied, and the measures for fertilizer reduction and controlling the losses of nitrogen and phosphorus from sweet corn farmland were explored. Field experiments were conducted with treatments: (1) no fertilizer (CK); (2) conventional fertilization (CF); (3) formula fertilizer (FF); (4) FF + organic fertilizer (OFFF); (5) FF + biochar (BFF); (6) FF + controlled-release urea (CRUFF); (7) FF + controlled release BB fertilizer (UCRF). The results showed that under the condition of reducing nitrogen fertilizer by 20%, there was no significant difference between the treatments of CF and FF, BFF, CRUFF, but the difference between the treatments of OFFF and UCRF (P<0.05) were significant. The yield of sweet corn of OFFF and UCRF increased by 17.8% and 16.8% respectively compared with that of CF. During the growth period of sweet corn, the total nitrogen concentration of runoff showed a gradual downward trend, and the total amount of CF nitrogen loss was the largest, reached 3.54 kg/hm². The total amount of nitrogen loss in farmland was significantly reduced under the condition of reduced fertilization rate, with a decrease of 18.4%-45.5%, of which CRUFF was the most significant, followed by UCRF, OFFF and BFF. Under reduced fertilizer rate, the total phosphorus loss of OFFF, FF and UCRF were significantly reduced (P<0.05), with the decrease rate of 46.7%-60.0%, of which OFFF was the most significant. The concentration of nitrogen and phosphorus in shallow groundwater could reflect the nitrogen and phosphorus leakage of farmland to a certain extent. The nitrogen and phosphorus concentration of shallow groundwater of CF during the growth period of sweet corn was the highest of 45.85 and 4.10 mg/L, respectively, while the total nitrogen concentration of CRUFF was 22.79 mg/L, which was 50.3% lower than that of CF. The highest phosphorus concentration was 2.73 mg/L, which was 33.4% lower than that of CF. The nitrogen in the shallow groundwater was mainly in the form of ammonium nitrogen. Compared with traditional fertilization, formula fertilizer (21.2-6.36-18.42) aiming to reduce nitrogen by 20% and its combining application with controlled-release urea, controlled-release bulk blending fertilizer and organic fertilizer respectively could not only achieve high yield, but also effectively prevent and control the losses of nitrogen and phosphorus from farmland, reducing the risk of non-point source pollution.