Reallocating crop rotation patterns improves water quality and maintains crop yield

Authors: JIANG, FEI - Pennsylvania State University; DROHAN, PATRICK - Pennsylvania State University; CIBIN, RAJ - Pennsylvania State University; PREISENDANZ, HEATHER - Pennsylvania State University; WHITE, CHARLIE - Pennsylvania State University; Veith, Tameria - Tamie

Submitted to: Agricultural Systems
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/2/2020
Publication Date: 12/31/2020
Citation: Jiang, F., Drohan, P.J., Cibin, R., Preisendanz, H.E., White, C., Veith, T.L. 2020. Reallocating crop rotation patterns improves water quality and maintains crop yield. Agricultural Systems. 187:103015. https://doi.org/10.1016/j.agsy.2020.103015.
DOI: https://doi.org/10.1016/j.agsy.2020.103015

Interpretive Summary: It is difficult to grow crops to produce enough food without losing sediment and nutrients from the fields into the nearby streams. Using a water quality simulation model (the Soil and Water Assessment Tool) in a northeastern US watershed, we simulated eight years of yield and of nutrient and sediment loss for four corn-soybean-hay crop rotations. Based on soil properties within the watershed, we moved the locations of the crop rotations within the watershed to maintain the same crop yield overall but to improve water quality at the watershed outlet. This research, based on a framework that is being considered in Europe, showed that the watershed water quality could potentially be improved by switching around 70% of the crop rotations among the available agricultural land. However, a next important step is to consider the production feasibility of these crop changes within the existing farm systems.

Technical Abstract: Meeting the growing food production needs of a society, while simultaneously maintaining or improving water quality, is a challenge facing many watersheds around the world. Across many nations, entrepreneurial agriculture is a norm where farmers dictate what to plant and when based on market demand. As an alternative. the European Union (EU) has explored the potential of a soil-based land use framework in achieving economic and environmental targets in agriculturally dominated watersheds; however, this framework has not been explored in US. We investigated the potential for a EU styled soil-based land use framework to improve water quality (ecosystem service water purification) while maintaining crop yields (ecosystem service food production) in a sub-watershed of the Chesapeake Bay. The Soil and Water Assessment Tool (SWAT) was utilized to model crop growth, and losses of total nitrogen (TN), total phosphorus (TP) and sediment for an 8-year period (2010 - 2017). An optimum crop reallocation scenario was designed, such that the locations of 4 crop rotations within the watershed were changed based on soil properties, but the watershed acreage of each remained the same. Considering only areas currently in agricultural production, we reallocated hay onto landscapes most vulnerable to erosion and nutrient loss, whereas corn-soybean rotations were reallocated onto less vulnerable areas. In the optimum reallocation scenario, 28% of agricultural lands remained the same crop rotation as the baseline scenario while 72% were reassigned. SWAT simulation results indicate crop reallocation alone reduced TN, TP and sediment losses by 15%, 14% and 39%, respectively at an annual average scale, which suggests that simply redistributing crops across an impaired watershed can make significant water quality improvements even without additional structural best management practices. Although watershed-scale benefits were evaluated here, future research is needed to understand how this approach affects farm-level factors, as implementation may require a percentage of farmers to change the type of crops they grow.