Publication Date
1989
Description
Economic and environmental concerns are prompting a heightened interest in using forage legumes in crop rotations to provide nitrogen (N) to subsequent non-legume crops. Yet there is a lack of information on the amount or proportion of N from forage legumes available to subsequent crops. Many fertilizer recommendations base legume N contributions on a fertilizer replacement value (FRY), which is the amount of inorganic N required to produce a subsequent non-legume crop yield equivalent to that produced following a legume. Legume N contributions based on FRY methodology typically exceed 100 kg N ha-1 (e.g. Bruulsema and Christie, 1987; Voss and Shrader, 1979). Another method of quantifying the N-supplying capacity of legumes is to trace ISN from labeled residues into a subsequent crop. However, few field studies using 15N-labeled legumes have been conducted. This paper describes experiments conducted in the Northern U.S.A., in which ISN was traced from alfalfa (Medicago sativa L.) and red clover (Trifolium pratense L.) residues into subsequent com (Zea mays L.) and spring barley (Hordeum vulgare L.) crops. The objectives of these experiments were : i) to quantify the N contribution from alfalfa and red clover to a succeeding com crop, ii) to quantify legume-N remaining in soil fractions after com, and iii) to quantify the N contribution from the forage legumes to a second succeeding crop, spring barley.
Citation
Hesterman, O B.; Harris, G H.; and Griffin, T S., "Quantifying the Nitrogen-Supplying Capacity of Legumes to Non-Legumes in Crop Rotations Using 15N" (2025). IGC Proceedings (1989-2023). 10.
https://uknowledge.uky.edu/igc/1989/session2/10
Included in
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Quantifying the Nitrogen-Supplying Capacity of Legumes to Non-Legumes in Crop Rotations Using 15N
Economic and environmental concerns are prompting a heightened interest in using forage legumes in crop rotations to provide nitrogen (N) to subsequent non-legume crops. Yet there is a lack of information on the amount or proportion of N from forage legumes available to subsequent crops. Many fertilizer recommendations base legume N contributions on a fertilizer replacement value (FRY), which is the amount of inorganic N required to produce a subsequent non-legume crop yield equivalent to that produced following a legume. Legume N contributions based on FRY methodology typically exceed 100 kg N ha-1 (e.g. Bruulsema and Christie, 1987; Voss and Shrader, 1979). Another method of quantifying the N-supplying capacity of legumes is to trace ISN from labeled residues into a subsequent crop. However, few field studies using 15N-labeled legumes have been conducted. This paper describes experiments conducted in the Northern U.S.A., in which ISN was traced from alfalfa (Medicago sativa L.) and red clover (Trifolium pratense L.) residues into subsequent com (Zea mays L.) and spring barley (Hordeum vulgare L.) crops. The objectives of these experiments were : i) to quantify the N contribution from alfalfa and red clover to a succeeding com crop, ii) to quantify legume-N remaining in soil fractions after com, and iii) to quantify the N contribution from the forage legumes to a second succeeding crop, spring barley.
