IMPACT OF CONTINUOUS SUGAR BEET CROPPING ON POTASSIUM QUANTITY-INTENSITY PARAMETERS IN CALCAREOUS SOILS

Abstract

One hundred-eighteen surface soil samples (59 samples from cultivated areas and 59 samples from virgin soils) were studied to ascertain if potassium (K) quantity-intensity (Q/I) parameters of the soils are being changed by long-term sugar beet cropping. Long-term cultivation resulted in a significant decline in the equilibrium activity ratio (AR_e ^K) values from 0.012 to 0.0047 (moles/L)^1/2 (a drop of 61%) and from 0.013 to 0.008 (a drop of 38%) in Typic calcixerpts and Typic endoaquepts, respectively. Paired t-test revealed that continuous sugar beet cultivation led to significant changes in the easily exchangeable K (ΔK₀) values from −0.69 to −0.28 cmol_c/kg (a rise of 59%) the Typic calcixerepts soils. The highest values for PBC^K were associated with the soil types which had the greatest clay contents and smectite clay minerals. Results suggest that continuous sugar beet cropping caused a great decline in K supplying power of the soils.

Keywords:

• potassium
• continuous cropping
• quantity
• intensity

ACKNOWLEDGMENTS

Appreciation is expressed to the Iran National Science Foundation (INSF) for the financial support of this research. The assistance of the staff and technicians of the Soil Science Department, Urmia University, Mr. M. Barin, Mr. B. Dovlati, and Mr. Hasirchi is gratefully acknowledged.