Nitrogen balance for pulse crops in rotation with spring wheat

Authors: Sainju, Upendra

Submitted to: Agronomy
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/13/2026
Publication Date: 2/16/2026
Citation: Sainju, U.M. 2026. Nitrogen balance for pulse crops in rotation with spring wheat. Agronomy. 16. Article 463. https://doi.org/10.3390/agronomy16040463.
DOI: https://doi.org/10.3390/agronomy16040463

Interpretive Summary: Nitrogen balance, calculated from total nitrogen input and output and nitrogen retention in the soil, is a measure of agronomic performance and nitrogen loss to the environment. There is little information available about nitrogen balance for pulse crops and pulse crop-nonlegume rotations. An ARS scientist at Sidney, MT evaluated N balance based on total N input, output, and retention in the soil for pulse crops and pulse crop-spring wheat rotations from 2021 to 2024. He found that chickpea resulted in nitrogen surplus compared to lentil, pea, and spring wheat or chickpea-spring wheat reduced nitrogen deficit compared to lentil-spring wheat, pea-spring wheat, and spring wheat-spring wheat rotations due to lower nitrogen output and higher nitrogen retention in the soil. Spring wheat increased nitrogen loss to environment compared to pulse crops due to higher nitrogen fertilization rate. Producers can increase soil nitrogen retention and reduce nitrogen loss to the environment by growing chickpea alone or in rotation with spring wheat compared to other pulse crops or pulse crop-spring rotations.

Technical Abstract: Pulse crops, having the capacity for biological nitrogen (N) fixation, rarely receive N fertilizers, but information is scarce on N balance for pulse crops or pulse crop-spring wheat (Triticum aestivum L.) rotations. The objective of the study was to evaluate N balance based on N inputs and outputs and soil N sequestration rate for pulse crops and pulse crop-spring wheat rotations from 2021 to 2024 in the US northern Great Plains. Pulse crops (chickpea [Cicer arietinum L.], lentil [Lens culinaris Medik.], and pea [Pisum sativum L.]) were rotated with spring wheat to form four crop rotations (chickpea–spring wheat, lentilspring wheat, pea–spring wheat, and spring wheat–spring wheat). Total N input from N fertilization, biological N fixation, soil N mineralization, crop seed, and precipitation was 9–27% greater for pea than for other crops and greater for pea–spring wheat than chickpea–spring wheat and continuous spring wheat. Total N output from grain N removal, ammonia volatilization, denitrification, plant senescence, leaching, surface runoff, and gaseous emissions was 20–62% greater for spring wheat than pulse crops. Nitrogen sequestration rate at 0–15 cm was 89% greater for spring wheat than lentil and 106–107% greater for pea-spring wheat and spring wheat–spring wheat than lentil–spring wheat. Nitrogen balance was 215–356% greater for chickpea and pea than lentil and spring wheat and 114–118% greater for chickpea–spring wheat and pea–spring wheat than lentil–spring wheat. Greater N input increased N surplus for pea or pea-spring wheat, and greater N output increased N deficit for spring wheat or spring-spring wheat compared to lentil or lentil–spring wheat, indicating that pea alone or in rotation with spring wheat reduced N loss to the environment by increasing soil N storage compared to continuous spring wheat.