حامد جنیدی جعفری

The agricultural use of natural ecosystem is increasing in the Middle East because of population growth in the most countries. The type of cultivation could affect the content of soil organic matter in the rangeland use changes into agriculture. Therefore, we compared soil organic matter fractions of semi-arid rangelands with agricultural lands (wheat-land, pea-land and orchard) where have been changed from semi-arid rangelands to agriculture 15 years before. The results showed that in general, total and particulate organic matter (TOM and POM) and total nitrogen (TN) were highest in the rangeland compared with the three-agricultural lands in intact soil, macro-aggregates and micro-aggregates (p<0·05). Nevertheless, TOM content in orchard (1·45%) was higher than the two other land uses, and there was no significant difference of TN between natural rangeland and orchard in intact soil. The highest values of POM were obtained in the rangeland (0·23%) and orchard (0·22%), and the lowest value of POM was obtained in the pea-land (0·14%) and wheat-land (0·08%) in macro-aggregates. In micro-aggregates, TOM, POM and TN were highest in the rangeland (1·77%, 0·23% and 0·19%, respectively) and showed similar pattern in the three-agricultural lands. We discussed that compared with pea-land and wheat-land, orchard was received less negative impact on soil qualitative parameters in land use changes projects from rangeland into agriculture. We conclude that orchard could be a better option in rangeland use changes into agriculture compared with the other cultivations.