ارزيابي تغييرات برخي از خصوصيات فيزيكوشيميايي اراضي زراعي (تحت كشت نيشكر و تناوبي ) و بكر منطقه هفت تپه خوزستان

Evaluation of Changes in Physico-Chemical Properties in Cultivated

Sugarcane (Saccharum officinarum L.) fields and rotational crops have been cultivated without potassium fertilization for 42 and more than 100 years, respectively. Sugarcane fields receive approximately 30 000 m3 ha- 1 (or 300 cm) irrigation water while the latter receive 10 000 m3 ha-1 annually. As a result of long duration of cultivation as well as the amount of irrigation water consumed some alteration in physico-chemical properties of these soils might have happened annually as compared to physico-chemical properties of uncultivated fields. The objective of this research was to evaluate physico-chemical properties of soil with emphasis on changes in different forms of soil potassium. In cultivated fields both gypsum and calcium carbonate were reduced in surface soil as a result of leaching. The K uptake along with its leaching resulted in alteration of illite clay fraction to form expanding clay mineral in surface soils of cultivated fields. The above result was supported by XRD studies. This alteration was supported by changes in physico-chemical properties with special reference to increased fixed K and CEC. Fixed K in soils under rotation cropping system did not show any different trend as compared to soils of uncultivated fields. Nevertheless, it decreased in sugarcane cultivated.