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Dynamic model for the effects of K fertilizer on crop growth, K-uptake and soil-K in arable cropping. 2. Field test of the model |
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| Authors: | D J Greenwood T V Karpinets |
| Institution: | Horticulture Research International, Wellesbourne, Warwick, CV35 9EF, UK.;The Institute for the Protection of Soil from Erosion, Karl Marks Street, 70, 6, Kursk, Russia. |
| Abstract: | Abstract. The validity of the model described in Greenwood & Karpinets (1997) was tested against the results of single year, multi level K fertilizer experiments. Measurements of plant mass, %K in the plant and K activity ratio in soil had been made at harvest and at intervals during the growing season on spring wheat, summer cabbage and turnips. Reasonably good agreement was obtained between these measurements and simulated values when the two 'crop' parameters (defining the dependence of critical and maximum possible %K on plant mass) were adjusted for each crop. Also good agreement was generally obtained for plant weight and plant %K at harvest in less detailed experiments on 10 other crops. Values of the two 'crop' parameters for 12 of the crops were strongly correlated with one another suggesting that a single 'crop' parameter may be all that is required to define most inter-species differences in plant-K demand. Simulations with the model indicate that, in central England, no response of 10 crops to K fertilizer would be likely on soils containing more than 170 mg of 1 M ammonium nitrate extractable-K/kg of soil and having clay contents of between 15 and 45%. Shortcomings of the model and opportunities for advance are discussed. A simplified version of the model runs on the Internet at: http://www.qpais.co.uk/moda-djg/potass.htm |
| Keywords: | Potassium fertilizers potassium soil exchangeable potassium models vegetables wheat |