Coordinated evaporative demand and precipitation maximize rainfed maize and soybean crop yields in the USA

Abstract

To understand how climate change affects crop yields, we need to identify the climatic indices that best predict yields. Grain yields are most often predicted using precipitation and temperature in statistical models, assuming linear dependences.However, soil water availability is more influential for plant growth than precipitation and temperature, and there is ecophysiological evidence of intermediate yield maximizing conditions. Using rainfed maize and soybean yields for 1970-2010 across the USA, we tested whether the aridity index, that is, the ratio of precipitation and potential evapotranspiration seasonal totals and a proxy of soil water availability, better predicts yield than growing season precipitation total, average temperature and their interaction. We also tested for non-monotonic responses allowing for intermediate yield-maximizing conditions. The aridity index alone explained 77% and 72% of maize and soybean yield variability, compared with 78% and 73% explained by temperature, precipitation and their interaction. Yield responses were non-monotonic, with yields maximized at intermediate precipitation and temperature as well as at intermediate aridity index of 0.79 for maize and 0.98 for soybean. The yield maximizing precipitation also increased with growing season average temperature, faster in maize than soybean. The intermediate yield maximizing conditions show that rainfed maize and soybean yields could both increase and decrease depending on whether climatic conditions come closer to or deviate from the yield maximizing conditions in the future. In most counties, during 1970-2010, the precipitation and aridity index were lower and temperature higher compared with those maximizing yields, suggesting that climate change will reduce yields.

The Relationship between Climate, Agriculture and Land Cover in Matopiba, Brazil (1985–2020)

“…It was also based on their applicability and research into other variables, such as air humidity and soil moisture reserves. Soil water availability is more influential for plant growth than precipitation and temperature, and there is ecophysiological evidence of the use of intermediate conditions for maximizing crop yields [18].…”

“…In agriculture, policymakers have a considerable and growing international interest in evaluating cultivation adaptation and climatic resilience [16]. For decision making in regional agricultural planning and development, knowledge of the spatiotemporal patterns of crops and their performance over time is essential, as is the assessment of climate change [17,18].…”

Crop rotational diversity can mitigate climate‐induced grain yield losses

“…Crop yields can thus be negatively affected by both dry spells and excessive precipitation (Li et al., 2019; Troy et al., 2015). Even short periods of extreme conditions or co‐occurring adverse but not extreme growing conditions, like heat and water stress, can severely reduce yields (Brás et al., 2021; Hamed et al., 2021; Luan et al., 2022; Matiu et al., 2017; Vogel et al., 2019). There is an urgent need to adapt our cropping systems to reduce yield losses due to climate change (Challinor et al., 2014; Khanal et al., 2021).…”