The effect of changing garden ecosystem to agricultural ecosystem on some important properties of soil

Given that uninformed exploitation and unstable management resulting from the changes in land use system in a number of almond orchards of Saman plain in Chahar mahal and Bakhtiari province are seriously threatening these resources, an experiment was carried out to evaluate the intensity of soil destruction in these regions. It aimed to investigate the effect of changing land use system on the organic carbon, the total nitrogen, and the microbial respiration of the soil. For so doing, three land use systems in Saman plain including a permanent almond orchard, a permanent pasture, and an almond orchard changed to an agricultural land were selected. Samples were gathered from regular networks (30 × 30 m) of topsoil (0-30 cm depth) in the farming year of 2010. The total nitrogen, the organic matter, and the microbial respiration of the soil were measured using standard procedures. Data were analyzed with the help of SPSS and Excel software, following a completely randomized design. The analysis of variance indicated that changing a garden ecosystem to an agricultural one had a significant effect on the organic carbon, the total nitrogen, and the microbial respiration of the soil indices at P<0.01. Furthermore, comparing these indices using Duncan method revealed that there was a significant difference at P<0.01 between the mean of the organic carbon, the total nitrogen, and the microbial respiration of the soil in all three land use systems. Changing a garden ecosystem into an agricultural one decreased 54, 62, and 40 percent of the organic carbon, the total nitrogen and the microbial respiration of the soil, respectively. Preserving pasture lands and replacing pasture plants increased the organic carbon, the total nitrogen, and soil microbial respiration, respectively, to 35, 45, and 30 percent compared to the agricultural ecosystems. There was a significant positive relationship between the organic carbon, the total nitrogen, and soil microbial respiration variables. The correlation analysis of variables using the Pearson test confirms a significant correlation between these three variables at P<0.01. Generally speaking, the microbial respiration, total organic carbon, and nitrogen indices were respectively the most reliable indicators of soil quality for the region under scrutiny. The average values of these indices can be introduced as optimum limits for selecting alternative managements and different tillage methods in the aforementioned land use systems.