猪场肥水施用对玉米-小麦农田氨排放、氮素利用与表观平衡的影响

规模化生猪养殖废弃物已成为当前重要污染来源,为有效解决猪场废水所引发面源污染问题,有必要开展将其替代矿物氮肥(作为肥水)施用于农田的探索。以华北平原高度集约化玉米-小麦一年两熟轮作体系为对象,通过田间小区试验,定量研究猪场肥水施用对作物产量、氮素吸收、氮素利用效率、土壤矿质氮累积、氨挥发损失及轮作体系氮素表观平衡的影响。试验包括7个处理:不施肥对照(CK)、尿素表施(CK1)、尿素注射施用(CK2)、猪场肥水替代25%尿素氮表施(25%WB)、猪场肥水替代50%尿素氮表施(50%WB)、猪场肥水替代25%尿素氮注射施用(25%WI)和猪场肥水替代50%尿素氮注射施用(50%WI)。猪场肥水作为基肥施用。结果表明,与CK相比,施用尿素和猪场肥水均可显著提高玉米、小麦产量和籽粒氮吸收量,其中25%WI最高,50%WI次之。与尿素表施相比,尿素注射施用、猪场肥水表施和注射施用均可明显提高氮肥农学效率、偏生产力和表观利用率,且肥水注射施用最高,肥水表施次之,而25%WI和50%WI之间无显著差异。与不施肥处理相比,施用尿素和猪场肥水0～100cm土体矿质氮残留量显著增加50.8%～87.9%,其中50%WB、25%WI和50%WI无显著差异。与尿素表施相比,尿素注射施用、肥水表施和注射施用均可显著降低玉米和小麦基肥期土壤氨损失总量,降幅分别为26.5%～48.6%和11.4%～29.1%;同时,肥水表施和注射施用下轮作体统氮盈余显著降低7.6%～16.0%,其中25%WI降幅最高,但与50%WI无显著差异。综合考虑作物产量、氮素利用和环境效应,猪场肥水替代25%和50%尿素氮注射施用是该区玉米-小麦轮作农田猪场肥水最佳施用方式。

Effects of swine slurry application on ammonia emission, nitrogen utilization and apparent balance of a winter wheat-summer maize rotation system

With the development of intensive swine production in China, large amounts of slurry are produced, which causes nitrogen and phosphorus loss and serious non-point pollution. A potentially efficient way to solve these environmental problems is to substitute mineral fertilizer with swine slurry in intensive maize (Zea mays L.)-wheat (Triticum aestivum L.) double-cropping rotation systems, which could promote the development of sustainable agriculture and animal husbandry. A field experiment was performed with swine slurry application in a maize-wheat double-cropping rotation system in the North China Plain. The study included the following seven treatments with three replications:zero-N control (CK); urea broadcast (CK1); urea injection (CK2); swine slurry as a substitute for 25% urea-N broadcast (25%WB), 50% urea-N broadcast (50%WB), 25% urea-N injection (25%WI), and 50% urea-N injection (50%WI). Swine slurry was applied to the soil before maize and wheat seeding. Compared with the CK, the application of urea and swine slurry significantly improved maize and wheat grain yield and N uptake, with the greatest effect seen in the 25%WI, followed by the 50%WI. Compared with the CK1, the N agronomic efficiency, N partial productivity, and apparent N recovery rate under treatments of urea injection and swine slurry broadcast and injection were significantly improved. The greatest improvement was seen in treatments of swine slurry injection, followed by treatments of swine slurry broadcast, but no significant difference was found between the 25%WI and 50%WI treatments. Compared with CK, the application of urea and swine slurry significantly improved nitrate accumulation. The increase in inorganic nitrogen ranged from 50.8%-87.9% throughout the 0-100 cm soil profile after maize harvest. No significant difference in nitrate accumulation was found among the 50%WB, 25%WI, and 50%WI treatments. Compared with CK1, swine slurry broadcast and urea and swine slurry injection significantly reduced the total amount of ammonia loss during the seeding period of maize and wheat, with reductions ranging from 26.5% to 48.6% and 11.4% to 29.1%, respectively. Meanwhile, swine slurry broadcast and injection significantly reduced N surplus from 7.6% to 16.0%, with the biggest difference found in the 25%WI treatments. However, no significant difference was found between the 25%WI and 50%WI treatments. In view of the yield, nitrogen utilization, and environmental benefits, swine slurry as a substitute for 25% and 50% urea-N injection were reasonable methods of swine slurry application in the intensive summer maize-winter wheat double-cropping rotation field.