Abstract
Winter cover crops (CC) use water, which can have negative, neutral, or
positive effects on soil water storage and supply for the subsequent
summer crop. There is a lack of information on how tillage impacts water
utilization by CC. A plot-scale Long-Term Agro-Ecosystem Research (LTAR)
experiment was initiated in October 2018 at Stoneville, MS, to estimate
crop water use and depletion (net loss) in two CC treatments [no-cover
(NC) and CC (Austrian pea, Pisum sativum L.)] under two tillage
[conventional tillage (CT) vs. no-tillage (NT)] practices in cotton
(Gossypium hirsutum L.) and sorghum (Sorghum bicolor L.) cropping
systems. Soil volumetric water content (VWC, %) was monitored using
capacitance sensors at 12 soil depths to 115 cm. In-field measurement of
VWC was recorded every 30 minutes. In the first year (Dec 2019–May
2020), the total VWC of the 0-45 cm soil profile was similar for all
treatments until mid-March, when CC plots depleted more water than NC,
especially for CT. No effect of CC on VWC was observed in the 45-115 cm
profile. The CC did not affect VWC in NT plots. In the second year (Nov
2020–May 2021), NT (both CC and NC) quickly restored water depleted by
cotton or sorghum (May to October 2020) in the whole 0-115 cm soil
profile, whereas, for CT, VWC was not restored in the 45-115 cm depth
until February. The CC-CT depleted more water in 35-55 cm depth in April
and May, relative to NC-NT and CC-NT treatments. The business-as-usual
CT-NC management system consumed soil water intermediate between NT
systems and CC-CT during most of the measurement period. These results
demonstrated that NT-CC can benefit row crop production systems with
minimal use of water and supply water compared to NC for cotton and
sorghum production.