控释尿素施用比例对旱地春玉米产量及土壤硝态氮残留量的影响

Effects of controlled-release urea application ratios on dryland spring corn yield and soil nitrate nitrogen residues

【目的】探讨控释尿素施用比例对春玉米产量和土壤硝态氮残留的影响,为研究区氮肥的科学施用及减少环境风险提供科学依据。【方法】于2017-2019年在黄土高原南部旱地春玉米上开展了3年的原位试验,试验中总氮施用量为200 kg/hm 2,按照氮肥中控释尿素的施用比例,设置不施氮对照(CK)、控释尿素0%+普通尿素100%(NC0)、控释尿素35%+普通尿素65%(NC35)、控释尿素50%+普通尿素50%(NC50)、控释尿素65%+普通尿素35%(NC65)5个处理,研究控释尿素施用比例对玉米产量、土壤微生物量碳(SMBC)、微生物量氮(SMBN)含量以及硝化潜势、硝态氮残留量的影响。【结果】与CK相比,施用氮肥显著增加了春玉米产量。施用不同比例控释尿素可对春玉米产量产生不同的影响,其中当控释尿素施用比例为50%(NC50)时,春玉米产量与NC0处理无显著差异;但当控释尿素施用比例为35%(NC35)和65%(NC65)时,春玉米产量较NC0处理分别显著降低了5.76%和14.39%。5个处理中,NC50处理0~20和20~40 cm土层的SMBC和SMBN含量均最高,与NC0处理相比其SMBC和SMBN含量分别显著增加了14.7%,23.5%和11.9%,41.6%。与CK相比,施用氮肥可以显著增加土壤硝化潜势(P<0.05)。与NC0处理相比,施用控释尿素处理0~20和20~40 cm土层的土壤硝化潜势分别下降了6.8%~22.3%和17.5%~41.3%,且2个土层均以NC50处理土壤硝化潜势的降低幅度最大,其与NC35和NC65处理的差异均达显著水平。与NC0处理相比,NC65、NC50和NC35处理0~300 cm土层中硝态氮残留量分别显著降低了17.89%,27.16%和34.96%。【结论】施用控释尿素可以减缓土壤硝化潜势,减少0~300 cm土层中硝态氮残留量,降低土壤中硝态氮淋溶累积风险,是调控土壤氮素淋溶的有效措施,在黄土高原南部春玉米连作区适宜推广的控释尿素配施比例为50%左右。

【Objective】This study explored the impact of controlled-release urea application ratios on spring corn yield and soil nitrate nitrogen residues to provide basis for scientific application of nitrogen fertilizers and reduction of environmental risks.【Method】In 2017-2019,a three-year in-situ experiment was carried out on dryland spring maize in the southern Loess Plateau with the total nitrogen application rate of 200 kg/hm 2.According to the application ratio of controlled-release urea in nitrogen fertilizer,five treatments of no nitrogen control treatment(CK),controlled release urea 0%+ordinary urea 100%(NC0),controlled release urea 35%+ordinary urea 65%(NC35),controlled release urea 50%+ordinary urea 50%(NC50),and controlled release urea 65%+ordinary urea 35%(NC65)were used to study the effect on corn yield,carbon and nitrogen contents in soil microbial biomass,nitrification potential and nitrate nitrogen residue.【Result】Compared with CK,the yield of spring maize was significantly increased by applying nitrogen fertilizer.Application of controlled-release urea in different ratios had different effects on spring maize yield.NC50 showed no significant difference in spring corn yield in comparison with NC0.NC35 and NC65 significantly reduced yield by 5.76%and 14.39%.Among the 5 treatments,the contents of SMBC and SMBN in NC50 were the highest with significant increases of 14.7%and 23.5%in soil layer of 0-20 cm and 11.9%and 41.6%in soil layer of 20-40 cm,respectively.Compared with CK,application of nitrogen fertilizer significantly increased soil nitrification potential(P<0.05).Compared with NC0,the soil nitrification potential in the 0-20 and 20-40 cm soil layers in controlled-release urea treatments were decreased by 6.8%-22.3%and 17.5%-41.3%,respectively.Among the two soil layers,NC50 had the largest reduction in soil nitrification potential with significant difference in comparison with NC35 and NC65.Compared with NC0,the soil nitrate nitrogen residues in the 0-300 cm soil layer in NC65,NC50 and NC35 treatments were significantly reduced by 17.89%,27.16%and 34.96%,respectively.【Conclusion】Application of controlled-release urea is an effective measure to control soil nitrogen leaching by reducing soil nitrification potential,residual nitrate nitrogen in 0-300 cm soil layer,and cumulative risk of nitrate nitrogen leaching in soil.The suggested application ratio of controlled-release urea in the spring maize continuous cropping area in the southern Loess Plateau was about 50%.