Precision management and precipitation influence productivity and nutrients availability in dryland cropping system

Authors: Mikha, Maysoon; Mankin, Kyle; KHAN, SHAHBAZ - Colorado State University; Barnard, David

Submitted to: American Society of Agronomy
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/17/2024
Publication Date: 9/9/2024
Citation: Mikha, M.M., Mankin, K.R., Khan, S.B., Barnard, D.M. 2024. Precision management and precipitation influence productivity and nutrients availability in dryland cropping system. American Society of Agronomy. (2024):1–19. https://doi.org/10.1002/agj2.21686.
DOI: https://doi.org/10.1002/agj2.21686

Interpretive Summary: Dryland farmers use cropping and nutrient management decisions to deal with the risk of poor weather. When these decisions are tailored to specific field conditions, it is called precision management (PM). The goal is not just to increase yields but also to minimize inputs to improve net profits. We evaluated one such PM approach in a dryland farming system. We compared an aspirational (ASP) no-till system with three crops in four years (winter wheat, corn, millet, fallow/flex) to a business-as-usual (BAU) reduced tillage system with two crops in four years (wheat, fallow). The ASP system also divided the field into three PM zones that received either low, medium, or high nitrogen (N) rates. We found that winter wheat yields were the same or larger using ASP compared to BAU even while adding a third crop every four years. Within the ASP system, wheat, corn, and millet yield increased from low- to medium- to high-PM zones in response to greater applied N, but only during years with more rain. Yield responded not only to in-season rainfall but also to rainfall distribution in the growing season. The low soil organic matter accumulation combined with nutrient removal by the harvested crops reduced soil nutrients. The more diverse and intensive ASP crop rotation with in-field nutrient management was able to maintain or improve crop yields, which should lead to increased farmer profits compared to the conventional BAU cropping system.

Technical Abstract: Precision agricultural management could increase land productivity, reduce inputs, and enhance net economical return while enhancing cropping system resiliency to climate change. The objective of this study was to evaluate how climate (precipitation) and aspirational (ASP) precision management (PM), no-till, 4-year rotation of winter wheat-corn-millet-fallow/flex (W-C-M-F/f) influenced yields and soil nutrients compared to a business-as-usual (BAU), reduced tillage (RT), 2-year rotation of wheat-fallow (W-F) in a dryland agricultural system. Phases of each rotation were included yearly throughout the study period (2018-2022) with three replications. In three PM zones in each ASP field, nitrogen applications were assigned to high, medium, or low application rates based on 2018 yield at the beginning of the study. Years with low in-season precipitation had a significant reduction in wheat and corn production (2020, 2022) and complete millet yield failures (2020, 2021). Low soil organic matter (SOM) accumulation (0.1-0.5%) and the reduction in soil nutrient status suggested that the addition of soil nutrients needs to be considered to prevent soil-nutrient degradation. Our results suggest that under favorable precipitation, wheat, corn, and millet yields responded to PM treatments, with yields increasing with increasing N addition. The ASP treatment added a third crop every four years and did so without significantly decreasing wheat yield following fallow. ASP management shows promise as an alternative to BAU in the Great Plains dryland projection region.