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Cover Crops and Irrigation Impacts on Soybean Production in the Mississippi Delta
Proceedings of the 2022 Mississippi Water Resources Conference
Year: 2022 Authors: Kaur G., Russell D., Singh G., Quintana N.
Excessive groundwater pumping for irrigation has declined water levels in the Mississippi River Valley Alluvial Aquifer. Potential solutions to groundwater conservation can be adopting management practices such as irrigation scheduling using sensors and planting cover crops. A study was conducted from 2019 to 2021 at the National Center for Alluvial Aquifer Research, Leland, MS to determine the impact of cover crops and sensor thresholds for irrigation scheduling on soybean production, water productivity, and irrigation water use efficiency (IWUE). The cover crops included in the study were: cereal rye (Secale cereale L.), hairy vetch (Vicia villosa R.), wheat (Triticum aestivum L.) + radish (Raphanus sativus L.) + turnip (Brassica rapa L.) mix, and no cover crop control. Irrigation treatments included: no irrigation/rainfed, -40 kPa, and -90 kPa sensor threshold for irrigation initiation. The experimental design was a randomized complete block with four replications. The highest soybean yield was obtained in hairy vetch treatments under the -40 kPa irrigation threshold in 2020. No significant differences were found for soybean yield in 2021. Water productivity was at least 10% lower in all treatments under the -40 kPa irrigation threshold compared to all other treatments in 2020. The water productivity was highest in -90 kPa followed by no irrigation and -40 kPa sensor threshold treatments in 2021. The IWUE was higher in cereal rye treatment than the other cover crop treatments in 2021. When data was averaged over two years, net returns above total specified expenses were highest in no cover crop treatments under the -40 kPa irrigation threshold.