Effect of land use on physical and chemical parameters of soil and sediment in Qarnave and Yelcheshme watersheds, Golestan Province, Iran

The objective of this investigation was assessment of physical and chemical parameters ofsoil and sediment in loess lands under different land uses, in the north of Iran. A yearly soilsampling was carried out randomly in three land uses (cultivated, forest and pasture) inQarnave and Yelcheshme watersheds. Sediment samples were taken monthly in thewatersheds at the hydrometrical station of Tamer located in downstream of the watersheds.The results showed that soil texture was silty clay loam and silty loam in forests andcultivated lands, respectively. In both watersheds, the highest amount of pH, carbonatecalcium, available phosphorus (P) and bulk density (BD) was observed in cultivated lands,whereas the highest amount of total nitrogen (TN), mean weight diameter (MWD) andorganic carbon (OC) was observed in forest. The highest amount of TN was observed inautumn, whereas the maximum amount of K was observed in summer, in both soil andsediment samples. The highest amount of P in soil and sediment was observed in summerand winter respectively. Also, the highest percentage of OC in soil and sediment wasobserved in autumn and summer respectively. The results showed that tillage and soilcultivation in cultivated lands may lead to reduction of OC and BD, therefore, decreasingthe MWD.