Nelson Nathan O, Roozeboom Kraig L, Yeager Elizabeth A, Williams Jeffery R, Zerger Sarah E, Kluitenberg Gerard J, Tomlinson Peter J, Abel David S, Carver R Elliott
Dep. of Agronomy, Kansas State Univ., 2004 Throckmorton Plant Sciences Center, 1712 Claflin Rd., Manhattan, KS, 66506, USA.
Dep. of Agricultural Economics, Kansas State Univ., 342 Waters Hall, 1603 Old Claflin Pl., Manhattan, KS, 66506, USA.
J Environ Qual. 2023 Jan;52(1):113-125. doi: 10.1002/jeq2.20427. Epub 2022 Dec 9.
Phosphorus (P) fertilization practices and winter cover crops are promoted to protect water quality yet can potentially influence crop yield and profitability. This study examined the impacts of three P fertilizer management practices (no P, fall broadcast P, and spring injected P) and winter annual cover crop use on yields, net returns, and water quality in a no-till corn-soybean rotation. Treatments were replicated in a 4-yr field study where sediment, total P, and dissolved reactive P (DRP) losses in edge-of-field surface runoff were continuously monitored. Production budgets were developed for each treatment and coupled with water quality data to identify optimal practices and opportunity costs for improving water quality. Applying P fertilizers increased crop yield regardless of application method or cover crop, but the response was more pronounced in corn than soybean. The cover crop reduced corn grain yield in 1 yr with high temperature and low precipitation but did not impact grain yield in the other corn year or either year of soybean. The most profitable treatment was fall broadcast P fertilizer with no cover crop, which also had the greatest total P and DRP losses and near greatest sediment loss. The lowest-cost methods of reducing total P, DRP, and sediment losses were, respectively, no P fertilizer without a cover crop ($47.56 kg total P), spring injected P fertilizer without a cover crop ($56.47 kg DRP), and spring injected P fertilizer with a cover crop ($0.16 kg sediment). Widespread adoption of these practices will likely require monetary incentives.
施用磷肥和种植冬季覆盖作物有助于保护水质，但可能会对作物产量和盈利能力产生潜在影响。本研究考察了三种磷肥管理方式（不施磷肥、秋季撒施磷肥和春季注入磷肥）以及冬季一年生覆盖作物的使用对免耕玉米-大豆轮作体系中作物产量、净收益和水质的影响。在一项为期4年的田间试验中对各处理进行了重复试验，持续监测了田边地表径流中的沉积物、总磷和溶解性活性磷（DRP）损失。为每个处理制定了生产预算，并结合水质数据，以确定改善水质的最佳做法和机会成本。无论施肥方式或是否种植覆盖作物，施用磷肥均能提高作物产量，但玉米的增产反应比大豆更明显。覆盖作物在1年高温少雨的情况下降低了玉米籽粒产量，但在另一年玉米季或大豆季均未影响籽粒产量。最盈利的处理方式是秋季撒施磷肥且不种植覆盖作物，该处理的总磷和DRP损失也最大，沉积物损失接近最大。减少总磷、DRP和沉积物损失的成本最低的方法分别是：不施磷肥且不种植覆盖作物（每千克总磷47.56美元）、春季注入磷肥且不种植覆盖作物（每千克DRP 56.47美元）以及春季注入磷肥且种植覆盖作物（每千克沉积物0.16美元）。广泛采用这些做法可能需要资金激励。
