The impact of soil organic matter (SOM) removal on availability and release of non-exchangeable potassium (NEK) in loessial soils of Golestan province

Soil organic matters (SOM) like soil mineral components also play an important role in soil chemistry. Soils responses are affected by the type and quantity of SOM. Decomposition of SOM is the most important factor in the production of acids in soil, which cause weathering of clay minerals (main resource of NEK) and releasing NEK. Besides the NEK quantity, the rate of potassium release and its availability in plant growth period are significantly important. The experiment was carried out as a factorial in completely randomized design including two factors, with three replications. First factor included four dominant soil series of Golestan province and the second factor contained blank, removal of SOM through H2O2 and NaOCl treatments. The results showed that NaOCl removed more SOM than H2O2. This means that H2O2 has less ability in the removal of SOM. The rate of NEK release was determined in soils with and without SOM. Kinetic experiments results indicated that total quantity of NEK from the soils in all treatments was maximum in Aliabad series at the end of extraction. The rates of NEK release were minimum at blank in Kordkoy series and in both SOM removed treatments in Daland series. More K was released in all soils in H2O2 removed treatment; whereas less K was released in NaOCl treatment. Consequently, SOM has direct and indirect effects on the chemical forms of K quantity and its kinetic release.