Combined influence of soil moisture and atmospheric evaporative demand is important for accurately predicting US maize yields

Abstract

Understanding the response of agriculture to heat and moisture stress is essential to adapt food systems under climate change. Although evidence of crop yield loss with extreme temperature is abundant, disentangling the roles of temperature and moisture in determining yield has proved challenging, largely due to limited soil moisture data and the tight coupling between moisture and temperature at the land surface. Here, using well-resolved observations of soil moisture from the recently launched Soil Moisture Active Passive satellite, we quantify the contribution of imbalances between atmospheric evaporative demand and soil moisture to maize yield damage in the US Midwest. We show that retrospective yield predictions based on the interactions between atmospheric demand and soil moisture significantly outperform those using temperature and precipitation singly or together. The importance of accounting for this water balance is highlighted by the fact that climate simulations uniformly predict increases in atmospheric demand during the growing season but the trend in root-zone soil moisture varies between models, with some models indicating that yield damages associated with increased evaporative demand are moderated by increased water supply. A damage estimate conditioned only on simulated changes in atmospheric demand, as opposed to also accounting for changes in soil moisture, would erroneously indicate approximately twice the damage. This research demonstrates that more accurate predictions of maize yield can be achieved by using soil moisture data and indicates that accurate estimates of how climate change will influence crop yields require explicitly accounting for variations in water availability.

Land‐Atmosphere Drivers of Landscape‐Scale Plant Water Content Loss

“…Widespread soil moisture and diurnal temperature amplitude individual effects as well as interactions that reinforce plant drying suggest that a single factor is not always stronger or more dominant in its influence on landscape‐scale plant function, at least for drylands here. The results suggest that soil moisture and VPD as well as their interactions should be explicitly considered in models that use empirical stress functions and in plant hydraulic schemes with plant water storages being implemented in dynamic global vegetation models (Fisher et al, 2018; Kennedy et al, 2019; Rigden et al, 2020).…”

“…There is currently no consensus on the degree to which vapor pressure deficit (VPD), soil moisture, and/or their coupled effects control ecosystem-scale plant function and how their effects on plant water stress should be modeled (L. Y. Liu et al, 2020;Novick et al, 2016;Rigden et al, 2020;Stocker et al, 2018).…”

“…With few studies evaluating drivers of the satellite‐based plant water content (Konings, Williams, et al, 2017), it is unclear how much climatic factors individually drive landscape‐scale plant water stress. There is currently no consensus on the degree to which vapor pressure deficit (VPD), soil moisture, and/or their coupled effects control ecosystem‐scale plant function and how their effects on plant water stress should be modeled (L. Liu et al, 2020; Y. Liu et al, 2020; Novick et al, 2016; Rigden et al, 2020; Stocker et al, 2018). Temperature and light intensity can further drive plant water stress through interacting with soil and atmospheric moisture and influencing stomatal function (Grossiord et al, 2020; Jarvis, 1976).…”

Statistically bias-corrected and downscaled climate models underestimate the severity of U.S. maize yield shocks

“…For season-total precipitation, there is less evidence of a clear bias that would affect maize yields-the most prominent feature is a tendency to overestimate the standard deviation across many central and southern counties. One potentially fruitful avenue for future work is to investigate the effects of bias-correction and downscaling on the representation of soil moisture, which is more important for plant growth 35 and may or may not be strongly correlated with cumulative precipitation depending on factors such as runoff, drainage, and irrigation 36 .…”

Managing Soils for Recovering from the COVID-19 Pandemic

“…In recent years, the increase of extreme weather events, especially pronounced dry spells, has already had a massive impact on aspects of both agriculture and forestry. Only in areas with sufficient water storage in the soil can yield losses that remain within acceptable limits [24]. However, the geographical distribution of soils and their quality and health varies spatially on all scales, from climatic zones to individual fields [25].…”