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Although prairies and conservation buffers are becoming popular to improve soil properties and environmental quality, very little is known about their influence on soil thermal properties. This study compared and quantified thermal conductivity (λ), thermal diffusivity (D), and volumetric heat capacity (C) of prairies (Tucker Prairie [TP] and Prairie Fork [PF]), conservation buffers (grass buffers [GB] and agroforestry buffers [AGF]), and corn (Zea mays L.)–soybean [Glycine max (L.) Merr.] rotation (COS) land uses in Missouri. Core and bulk soils were collected at 10‐cm depth increments. Soil thermal properties and water characteristic curves were determined at 0, −33, −100, and −300 kPa pressures. Additionally, soil organic C (SOC) and bulk density (BD) were also determined. The results showed that SOC was negatively correlated with λ and D and positively correlated with C. Significantly higher values of SOC and lower BD were observed for AGF, TP, GB, and PF than COS. Similarly, λ and D were significantly higher and C was lower under COS than the prairies and conservation buffers. The results suggest that a greater amount of SOC decreases the thermal conductance due to the insulating characteristics of SOC and acts as a barrier to heat transport. Therefore, AGF, TP, GB, and PF had lower thermal conductance to deeper soil depths, which helps to conserve more moisture as well as assist in increasing the longevity of SOC in the soil matrix. Our results imply that buffers and perennial vegetation can help reduce heat flow by increasing the thermal capacity and thereby mitigating climate change.

ABSTRACT. Interest in cover crops has been increasing in the Texas (1) irrigated cotton without a cover crop (CwoC-I), (2) irrigated cotton with winter wheat as a cover crop (CwC-I), (3) dryland cotton without a cover crop (CwoC-D), and (4) dryland cotton with a winter wheat cover crop (CwC-D) at the Texas A&M AgriLife Research Station at Chillicothe from 2011 to 2015. The average percent error (PE) between the CSM-CROPGRO-Cotton simulated and measured seed cotton yield was -10.1% and -1.0% during the calibration and evaluation periods, respectively, and the percent root mean square error (%RMSE) was 11.9% during calibration and 27.6% during evaluation. For simulation of aboveground biomass by the CSM-CERES-Wheat model, the PE and %RMSE were 8.9% and 9.1%, respectively, during calibration and -0.9% and 21.8%, respectively, during evaluation. Results from the long-term (2001-2015) simulations indicated that there was no substantial reduction in average seed cotton yield and soil water due to growing winter wheat as a cover crop.

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There is an increasing need to strategize and plan irrigation systems under varied climatic conditions to support efficient irrigation practices while maintaining and improving the sustainability of groundwater systems. This study was undertaken to simulate the growth and production of soybean [Glycine max (L.)] under different irrigation scenarios. The objectives of this study were to calibrate and validate the CROPGRO‐Soybean model under Texas High Plains’ (THP) climatic conditions and to apply the calibrated model to simulate the impacts of different irrigation levels and triggers on soybean production. The methodology involved combining short‐term experimental data with long‐term historical weather data (1951–2012), and use of mechanistic crop growth simulation algorithms to determine optimum irrigation management strategies. Irrigation was scheduled based on five different plant extractable water levels (irrigation threshold [ITHR]) set at 20%, 35%, 50%, 65%, and 80%. The calibrated model was able to satisfactorily reproduce measured leaf area index, biomass, and evapotranspiration for soybean, indicating it can be used for investigating different strategies for irrigating soybean in the THP. Calculations of crop water productivity for biomass and yield along with irrigation water use efficiency indicated soybean can be irrigated at ITHR set at 50% or 65% with minimal yield loss as compared to 80% ITHR, thus conserving water and contributing toward lower groundwater withdrawals. Editor's note: This paper is part of the featured series on Optimizing Ogallala Aquifer Water Use to Sustain Food Systems. See the February 2019 issue for the introduction and background to the series.