Influence of crops on soil properties in agricultural lands of northern Iran.

This study evaluates the effects of land use and soil management on a combination of physico-chemical, biological and hydrological properties of soil, in order to assess its quality. Three land uses were selected at the Fuman area, near Masouleh (Iran), grouping soils covered by tea, garden crops and rice. A total of 24 soil samples (3 land uses × 4 replications × 2 soil layers, topsoil and sub-surface soil) was collected; microbial respiration, available water, stability of soil aggregates, pH, organic matter, cation exchange capacity and nutrient content (P, K, N, Mg and Ca) were determined in each land use/soil layer. In comparison with other land uses, garden showed the highest available water, aggregate stability, microbial respiration, nutrient contents and cation exchange capacity, whereas the latter three soil properties had the lowest values in soils covered by tea and rice crops. Based on these results, under the experimental conditions garden had the highest soil quality among the investigated land uses. Conversely, much caution must be paid to some soil properties of tea and rice crops, such as cation exchange capacity, microbial respiration and nutrient contents, which are the lowest among the investigated land uses. Moreover, the differences in the analysed soil properties between the two soil sampling depths were statistically significant (p < 0.05). Finally, a Principal Component Analysis clearly clustered soils covered by garden, tea and rice crops in three differentiated groups according to the sampled soil properties. This study provides a contribution in understanding the variability of soil properties under different land uses, indicating that some of these properties must be considered with caution, in order to avoid a decay of soil health.