Applications in sustainable production

Abstract

It is known that there are several factors affecting potassium fixation and release in soils. Wetting and drying as well as freezing and thawing are considered to be of primary importance among these. In our previous experiments, potassium fixation of different soil types and nutrient levels was evaluated as well as the significance of soil properties controlling fixation capacities of soils. The objective of this experiment was to study the influence of a relatively high and a low temperature (25°C and 0°C) on potassium fixation capacities of selected soils. Soil samples were taken from seven sites of multilocation long‐term fertilization trials. Exchangeable K content (K_ex) in soils at both temperatures was significantly determined by soil characteristics, fertilizer rates and temperature. On the other hand, wet and dry K fixation (K_wf and K_df) were dependent on soil characteristics. From the results of a stepwise regression analyses, it was established that soil parameters and mineralogy plays a significant role in the relationship between wet and dry K fixation. After evaluating the effect of temperature on exchangeable potassium content, it was concluded that at 25°C, 40.7 percent of the value of K_ex could be attributed to soil K₂O content, total quantity of kaolinite plus chlorites in soils. At 0°C, 63.5 percent of the value of exchangeable K was attributed to soil K₂O, humus and illite content. Comparing the correlation coefficients obtained for the variables studied, it was concluded that the correlation between K_ex and K_wf was the closest.