Potassium content in soil,uptake in plants and the potassium balance in three European long-term field experiments |
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Authors: | Blake L Mercik S Koerschens M Goulding KWT Stempen S Weigel A Poulton PR Powlson DS |
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Institution: | (1) Soil Science Department, IACR-Rothamsted, Harpenden, Herts, AL5 2JQ, UK Fax No;(2) Department of Agricultural Chemistry, Agricultural Universizy of Warsaw, Warsaw, Poland;(3) Soil Science Department, Centre for Environmental Research, Bad Lauchstaedt, Germany |
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Abstract: | This study quantitatively assesses the fate of K derived from mineral fertilizers and organic manures and the effective K
balance in three long-term field experiments at Rothamsted (UK), Bad Lauchstaedt (Germany) and Skierniewice (Poland). Plant
availability, uptake and the overall utilization of K over the last 30 years (1965–1996) are discussed and related to soil
K Availability Indices determined by the standard methods used in each of the three countries. In addition, to provide a standard
comparison of the three sites, Exchangeable K (1 M NH4OAc) and Non-exchangeable K (K extracted by boiling with 1 M HNO3) were measured on one recent (1995) set of soil samples. Plant availability and utilization of K was partly related to clay
content, but more closely to the cation exchange surfaces associated with both mineral and organic constituents and also,
at Rothamsted, to the capacity of clay minerals to fix K. The recovery rate of K from mineral fertilizer by crops did not
exceed 62%. Fertilizers were least effective in the most strongly K fixing soil at Rothamsted (44% maximum) and most effective
in the soil with the highest cation exchange capacity (CEC) at Bad Lauchstaedt (62%), where the greater quantity of exchange
sites appear to be associated with humic material. Recoveries of K from farmyard manure (FYM) varied from 22–117% (values
of >100% indicating subsoil uptake or the release of reserves). Deficiencies of N, P and Mg in some treatments decreased the
effectiveness of applied K and may have caused increased leaching of K from the plough layer. FYM was generally more effective
than mineral fertilizer where mineral N and P were not applied because these nutrients were effectively supplied in the manure.
But the effectiveness of mineral K fertilizer decreased when applied in combination with FYM because FYM was the preferred
source of K. Where FYM application increased the CEC of soils, this also improved K utilization but only where K was not extensively
leached or fixed.
This revised version was published online in June 2006 with corrections to the Cover Date. |
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Keywords: | Fertilizer Long-term experiments Nutrient uptake Potassium balance Potassium dynamics Soil potassium |
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