Effectiveness of Conservation Crop Rotation for Water Pollutant Reduction from Agricultural Areas

Abstract

HighlightsAdjusting nitrogen (N) fertilization rates for corn following legumes can reduce N losses.Including perennial legumes in corn rotations can reduce nitrate-N losses and improve water quality.Crop rotations that include three or more years of legumes can be cost-effective.Corn-soybean was the most cost-effective, with a net benefit in nitrate-N loss reduction compared to continuous corn.Abstract. Legumes included in corn-based crop rotation systems provide a variety of benefits to the subsequent crops and potentially to the environment. This review aims to synthesize available data from the literature on legume N credits and the effects of crop rotations on water quality, as well as to analyze the cost benefits associated with different legume-corn rotation systems. We found that there was much variation in reported values for legume N credits to subsequent corn crops, from both empirical results and recommendations made by U.S. land grant universities. But despite inherent complexity, accounting for this contribution is critical when estimating optimal N fertilizer application rates as part of nutrient management. Results from research on the influence of crop rotations on water quality show that including legumes in corn-based rotation systems generally decreases nitrate-N concentrations in subsurface drainage discharge. Our cost analysis showed that incorporating legumes in cropping systems reduced N fertilizer and pesticide costs compared to conventional cropping systems, i.e., continuous corn and corn-soybean rotations, but extended rotations, such as corn-soybean-alfalfa-alfalfa-alfalfa, are not as profitable as conventional systems in the U.S. Midwest. In comparing continuous corn and corn-soybean rotations, although their impacts on water quality are not significantly different when using overall means from the literature data, corn-soybean rotations are more profitable than continuous corn. When using data from papers that directly compared the two, we found that switching from continuous corn to corn-soybean can provide a benefit of $5 per kg N loss reduction. The cost analysis methods used could be tailored to any location or management scenario with appropriate inputs and serve as a useful tool for assessing cost benefits for other agricultural conservation practices. Legume-corn crop rotations have the potential to be an effective conservation practice with the ultimate goal of improving water quality, and, with further research, these rotations could be made even more effective by integrating them into a multi-practice system. Keywords: Conservation practice, Cost analysis, Crop rotation, Nitrate, Nutrient management, Water quality.

The Impact of Various Types of Cultivation on Stream Water Quality in Central Poland

“…The high effectiveness of such zones was also noted in a study by [120], in which nitrate concentrations exceeding 100 mg/L were reduced by 99% with a zone width of 45 m. Finally, an interesting pattern to reduce the nitrate contamination of streams could be the use of crop rotation with leguminous plants, which are known for their major role in nutrient capture in soils [121]. It was proven that crop rotation with leguminous plants generally produces lower nitrogen runoff to groundwater and further streams than monocultures [122,123]. Such solutions require careful overall consideration and attention by managers on a local scale, as agriculture nonpoint sources remain a significant problem in such areas.…”

Harmful algal blooms in agricultural irrigation: risks, benefits, and management

“…Careful consideration of crop selection and rotation is also essential in minimizing the risk of HAB contamination (Koropeckyj-Cox et al, 2021). Compared to legumes, crops such as lettuce, corn, and tomatoes exhibit greater susceptibility to HAB toxin accumulation (Saqrane et al, 2009;Melaram et al, 2022).…”

An Overview of the Effectiveness of Agricultural Conservation Practices for Water Quality Improvement

“…The impact of constructed wetland on dissolved P in subsurface discharge was highly variable depending on the influent source, and the mean concentration reduction is a negative value (-31%), which means that, on average, the dissolved P concentration is higher in constructed wetland effluent than in the influent. Finally, one study (Koropeckyj-Cox et al, 2021) showed that corn-soybean rotation reduces dissolved P by 39% and corn-soybean-wheat rotation reduces dissolved P by 58%, but further research is needed to better understand the effectiveness of crop rotation in reducing dissolved P.…”

“…The cost-benefit analysis methods for conservation crop rotation and nutrient management effectiveness were based on simple calculations of net revenue, i.e., subtracting the total costs of production from the gross revenues from crop sales for each management scenario (Koropeckyj-Cox et al, 2021;Liu et al, 2021). This is similar to the USDA-NRCS (2020) recommended method of comparing practice benefits to costs and estimating the net effects.…”