Askegaard, Margrethe and Eriksen, Jørgen (2002) Exchangeable potassium in soil as indicator of potassium status in an organic crop rotation on loamy sand. Soil Use and Management, 18, pp. 84-90.
Limited to [Depositor and staff only]
In organic agriculture, where K may be a limited resource, reliable tools are important in the assessment of K availability in the soil in order to avoid K deficiency. We investigated the effect of four organic farming systems on the exchangeable K in the plough layer of a six-course crop rotation from 1994 to 1997. The accumulated K balances over the four years varied between
-49 and +120 kg K ha-1 and the corresponding exchangeable K (0-20 cm) in autumn 1997 was 7.1 and 9.6 mg K 100 g soil-1, respectively, as an average of the crop rotation. The exchangeable K fraction responded to the K application in manure and to the crop in the rotation. In an additional experiment, no yield response to K was found, despite a low level of exchangeable K. The exchangeable K was a useful indicator of changes in the K status in the farming system with the largest positive K balance whereas this K fraction was insufficient as an indicator in the other three farming systems. The considerable variation of exchangeable K through the crop rotation makes the soil test method most suitable at the crop rotation level where fluctuations caused by crop and management are smoothed out.
|EPrint Type:||Journal paper|
|Research affiliation:||Denmark > DARCOF II (2000-2005) > IV.1 (EXUNIT) Experimental units for research in organic farming systems|
|Deposited By:||Askegaard, Margrethe|
|Deposited On:||27 Jan 2003|
|Last Modified:||12 Apr 2010 07:27|
|Refereed:||Peer-reviewed and accepted|
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