A - Papers appearing in refereed journals
Scholefield, D., Lockyer, D. R., Whitehead, D. C. and Tyson, K. C. 1991. A model to predict transformations and losses of nitrogen in UK pastures grazed by beef-cattle. Plant and Soil. 132 (2), pp. 165-177.
|Authors||Scholefield, D., Lockyer, D. R., Whitehead, D. C. and Tyson, K. C.|
The model simulates the cycling of N in grassland systems grazed by beef cattle and predicts the annual amount of N in liveweight gain, and the amounts lost through ammonia volatilization, denitrification and leaching, on the basis of fertilizer application and soil and site characteristics. It aims to provide a better understanding of the way in which these various factors interact in their influence on N transformations. The model has been programmed to run on IBM-compatible personal computers and responds rapidly to changes in input parameters. The model has been constructed from the average annual amounts of N passing through various components of the N cycle in ten field systems grazed by beef cattle. The amounts were either measured directly or were calculated from empirical sub-models, assuming a balance between inputs to, and outputs from the soil inorganic N pool. The model is given wide applicability through the inclusion of a mineralization sub-model which is sensitive to soil texture, sward age, previous cropping history, and climatic zone. Another important sub-model determines the partitioning of soil inorganic N to either plant uptake or the process of loss: the proportion partitioned to plant uptake decreases as the total amount of soil inorganic N increases. Outputs from the model indicate that fertilizer N has a strong influence on ammonia volatilization, denitrification and leaching at a given site but that, over a range of sites with a given rate of fertilizer N, total loss and the proportions lost by the three processes are greatly influenced by the amount of N mineralized by the soil. The model indicates how fertilizer N should be matched with mineralization to limit gaseous and leaching losses and to achieve optimum efficiency of N use in grazing systems.
|Keywords||RRES175; 175_Soil science; 175_Livestock; 175_Ecology|
|Year of Publication||1991|
|Journal||Plant and Soil|
|Journal citation||132 (2), pp. 165-177|
|Digital Object Identifier (DOI)||doi:10.1007/bf00010397|
|Open access||Published as non-open access|
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