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ARS Home » Plains Area » Clay Center, Nebraska » U.S. Meat Animal Research Center » Livestock Bio-Systems » Research » Publications at this Location » Publication #401104
Research Project: Applying Nutritional Strategies to Improve Early Embryonic Development and Progeny Performance in Beef Cows

Location: Livestock Bio-Systems

Title: Alfalfa in rotation with annual crops reduced nitrate leaching potential

Author
item SINGH, ARSHDEEP - University Of Nebraska
item AFZAL, TAHSEEN - University Of Nebraska
item Woodbury, Bryan
item WORTMANN, CHARLES - University Of Nebraska
item IQBAL, JAVED - University Of Nebraska

Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/23/2023
Publication Date: 7/10/2023
Citation: Singh, A., Afzal, T., Woodbury, B.L., Wortmann, C., Iqbal, J. 2023. Alfalfa in rotation with annual crops reduced nitrate leaching potential. Journal of Environmental Quality. 52(3):930-938. https://doi.org/10.1002/jeq2.20473.
DOI: https://doi.org/10.1002/jeq2.20473

Interpretive Summary: Alfalfa has a deep root system that could potentially limit the amount of nitrate that leaches below the typical crop root zone. A study was conducted to determine the long-term effects on certain soil properties to a 25-foot depth with an alfalfa rotation compared with continuous corn. For the 0-25-foot depth, the alfalfa rotation had 36% less soil water, approximately 50% less nitrate and a 10 less total soil nitrogen. The greater depletion of soil water and nitrate with the incorporation of the alfalfa rotation was primarily below the crop rooting zone. This indicates no negative implications for corn following alfalfa but greatly reduced potential for nitrate leaching to the aquifer with the alfalfa rotation. The inclusion of an alfalfa rotation with corn greatly reduce leaching of nitrate to the aquifer when compared with continuous corn.

Technical Abstract: Rotation of perennial alfalfa (Medicago sativa L.) with annual crops has the potential to reduce nitrate-nitrogen (NO3-N) in the vadose zone and increase soil organic carbon (SOC) sequestration. The objective of this study was to determine the long-term effects on SOC, NO3-N, ammonium-N (NH4-N), and soil water in the 7.2 m depth with an alfalfa rotation compared with continuous corn (Zea mays L.). Soils from six pairs of alfalfa rotation versus continuous corn observation points were sampled to 7.2 m depth in 0.3 m increments. The uppermost 0.3 m was divided into 0–0.15 and 0.15–0.30 m. For the 0–7.2 m depth, the alfalfa rotation compared with continuous corn had 26% less soil water (0.29 vs. 0.39 g cm-3) and 55% less NO3-N (368 vs. 824 kg ha-1). The cropping system and NO3-N concentration did not affect NH4-N in the vadose zone. The alfalfa rotation compared with continuous corn had 47% higher SOC (105.96 Mg ha-1 vs. 72.12 Mg ha-1) and 23% higher total soil nitrogen (TSN) (11.99 Mg ha-1 vs. 9.73 Mg ha-1) in the 0–1.2 m depth. The greater depletion of soil water and NO3-N with alfalfa rotation was primarily below the rooting zone of corn, suggesting no negative implications for corn following alfalfa but greatly reduced potential of NO3-N leaching to the aquifer with the alfalfa rotation. Alfalfa rotation compared with continuous corn is a means to greatly reduce the leaching of NO3-N to the aquifer and improve the surface soil with the potential to increase SOC sequestration.