Evaluation of chemical methods for estimating plant available copper in soils of Rajasthan

Relative efficiency of ten chemical extractants for the extraction of available copper (Cu) in ten different soils of Rajasthan and its uptake by four different crops viz., wheat, cowpea, groundnut and soybean were studied in a pot culture experiment. To find out the suitability of various extractants for estimating available Cu in soils, simple correlations were worked out between the quantities extracted by ten extractants and the uptake of copper by four different test crops. It was concluded that the DTPA-CaCl₂ (pH 7.3) extractant gave higher correlation with Cu uptake by all four crops. Among the soil properties studied, pH was negatively correlated, whereas, it was significantly and positively related with that of organic carbon, CEC and clay content and poorly related with CaCO₃.