Influence of the potassium soil stock on potassium content in first cut grasland forage | Vpliv zalozenosti tal s kalijem na vsebnost kalija v travniski krmi prve kosnje
2008
Babnik, D., Agricultural Inst. of Slovenia, Ljubljana (Slovenia) | Susin, J. | Verbic, J. | Znidaric-Pongrac, V. | Znidarsic, T.
Thirty-six samples of first cut grass were harvested in practical conditions in years 2007 and 2008. At the same time and on the same parcels the soil samples were collected. Regression analysis was performed in order to establish the relationship between forage potassium content and soil stock of potassium or other soil properties. Determination coefficient between forage potassium content and available potassium in the soil (K2O extracted with ammonium acetate-lactate i.e. AL method) was low (R2=0.24). Slightly higher R2 for the prediction of forage potassium content was obtained when soil pH (R2=0.34), soil organic matter content (R2=0.44) and soil clay proportion (R2=0.46) were gradually added in to the model. Additional explanatory variables like exchangeable potassium and soil cation exchange capacity did not improve the determination coefficient of the prediction. It can be concluded, that data obtained from the standard soil analyses (available potassium in the soil, soil pH, soil organic matter content, soil texture) do not provide sufficiently reliable information for prediction of forage potassium content and/or estimation of actual demands for potassium fertilizer in practical conditions.
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