Publication Date
1989
Description
Improving the efficiency of nitrogen (N) utilization and reducing losses requires an understanding of N transformations in soils. A key process is nitrification, which qualitatively and quantitatively determines the fate of NH4 +. This is especially important in grazed grassland where returns of urinary N provide a large supply of NH4 +. After grazing has finished there may be accumulations of N which, if nitrified, will be lost by leaching (freely drained soils) or denitrification (poorly drained soils) in temperate regions. Where nitrification is restricted, opportunity for loss is correspondingly less. Field measurement of nitrification is difficult because of interactions with plant uptake and other transformations. However, sequential sampling allows-an estimate of changes in content and balance of soil NH4 + and NO3-, especially in autumn when both uptake and leaching/denitrification are minimal. We describe seasonal changes in mineral N and the effects of different N inputs to grassland ; implications for N loss are discussed.
Citation
Jarvis, S C.; Macduff, J H.; Williams, J R.; and Hatch, D J., "Balances of Forms of Mineral N in Grazed Grassland Soils Impact of N Losses" (2025). IGC Proceedings (1989-2023). 22.
https://uknowledge.uky.edu/igc/1989/session2/22
Included in
Agricultural Science Commons, Agronomy and Crop Sciences Commons, Plant Biology Commons, Plant Pathology Commons, Soil Science Commons, Weed Science Commons
Balances of Forms of Mineral N in Grazed Grassland Soils Impact of N Losses
Improving the efficiency of nitrogen (N) utilization and reducing losses requires an understanding of N transformations in soils. A key process is nitrification, which qualitatively and quantitatively determines the fate of NH4 +. This is especially important in grazed grassland where returns of urinary N provide a large supply of NH4 +. After grazing has finished there may be accumulations of N which, if nitrified, will be lost by leaching (freely drained soils) or denitrification (poorly drained soils) in temperate regions. Where nitrification is restricted, opportunity for loss is correspondingly less. Field measurement of nitrification is difficult because of interactions with plant uptake and other transformations. However, sequential sampling allows-an estimate of changes in content and balance of soil NH4 + and NO3-, especially in autumn when both uptake and leaching/denitrification are minimal. We describe seasonal changes in mineral N and the effects of different N inputs to grassland ; implications for N loss are discussed.
