Our overall project goal is to determine drought thresholds for which soil health management and associated SOC increases mitigate the effects of climate change on cotton yield. Our central hypothesis is that by incorporating realistic soil health effects in the Decision Support System for Agrotechnology Transfer (DSSAT) Cropping System Model (CSM) (Jones et al. 2003; Hoogenboom et al. 2019) we will identify drought index values for which soil health management negates the effects of climate change on cotton yield. For this one-year proposal, we have two main objectives:Objective 1: Quantify the impact of soil health management and associated SOC increases on the components of the soil water balance in DSSAT We have developed new pedotransfer functions (predictive empirical relationships) from the North American Project to Evaluation Soil Health Measurements (NAPESHM), with 124 sites across Canada, Mexico, and the U.S.A, relating increases in SOC, driven by management changes, to increases in plant available water. Based on those findings, our working hypothesis is that incorporating the new pedotransfer functions into DSSAT will improve the overall soil water holding characteristics and thus, simulate root water uptake and plant transpiration (H1.1). Our approach to testing this will be to compare modeled transpiration in the improved DSSAT version to the current version. Based on previous work outlined in the Background section, we expect that changes in permanent wilting point, field capacity, plant stress coefficients (based on water holding capacity), and soil evaporation will likely change the ratio of transpiration to evaporation and affect modeled yield (H1.2). This will be easily tested by comparing the ratio of transpiration to evaporation between the current and improved versions of DSSAT. Based on our prior work, we anticipate that iterative and holistic updates are needed to bring DSSAT in line with soil health knowledge. We expect that including additional effects of soil health management (e.g., residue effects on evaporation) and revising management selections to represent soil health systems (e.g., surface roughness and residue reflect real soil health management rather than untilled conventional fields) will result in greater transpiration (H1.3) which has the potential to increase cotton yield.Objective 2: Identify in what soil, management, and climatic scenarios soil health management and an increase in SOC will improve cotton resilience to climate change We hypothesize that there are upper and lower threshold levels of drought for which soil health management and associated SOC increases provide climate resilience to cotton production systems (H2.1). Using 30-year simulations to generate distributions of cotton yield, H2.1 will be tested using the Standardized Precipitation-Evapotranspiration Index (SPEI) to quantify drought severity and simulate cotton growth and response in conventional and soil health management systems. The relationship between drought severity and simulated cotton production will be analyzed across four U.S. cotton-producing states and two climate change scenarios. We also hypothesize that soil health management systems and associated SOC increases will show a greater positive effect on cotton production in a lower emissions scenario (H2.2) because higher emissions scenarios will have effects that overwhelm the benefits of soil health management. The two climate scenarios will provide model outputs for a direct test of this hypothesis.These objectives will allow simulation of realistic effects of soil health management systems for climate resilience in cotton that can elucidate under what conditions soil health management is effective at climate change mitigation. The novel empirical relationships from NAPESHM, along with our holistic approach to updating the water balance and management selections, will bring DSSAT in line with current soil health knowledge by correctly representing soil health management and soil properties. We will test and publish the effects of changes in SOC due to soil health management on climate resilience in cotton systems with specific attention to cotton yield and plant available soil water storage for crops. We will distill the relevant farmer-facing material from our peer-reviewed publication into a free factsheet that will be hosted and promoted by the Soil Health Institute. We will also deliver a guidance document that will outline data and algorithms needed for future model improvements. The guidance document will support the establishment of new soil health experiments targeted to improve models further and the improved DSSAT version will inform cotton producers and the cotton industry about the true benefits of soil health in climate-disrupted growing conditions.
INCREASING CLIMATE RESILIENCE AND SOIL HEALTH IN COTTON BY IMPROVING DSSAT
Objective
Investigators
Bagnall, D.; Hoogenboom, GE, .
Institution
SOIL HEALTH INSTITUTE
Start date
2024
End date
2025
Funding Source
Project number
NC.W-2023-07675
Accession number
1031863