{'fraction_non_alphanumeric': 0.022970903522205207, 'fraction_numerical': 0.0035732516590096988, 'mean_word_length': 4.975609756097561, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
The impact of long-term grazing on soil nutrients and carbon dynamics in Sabz Kou rangelands

In rangeland ecosystems, heavy grazing causes reduced input of aboveground litter to the soil. This may have important consequences for soil nutrient cycling and soil organic matter dynamics. Yet, the effect of grazing on soil nutrients and C dynamics in these ecosystems is not well-known. In this study, we evaluated soil nutrients and litter decomposition in two sites protected from grazing for 16-years in a semi-arid native rangeland (Sabz Kou region) in Central Iran. Soil sampling was performed to 15-cm depth in two adjacent non-grazed sites, and in one heavily grazed site at a distance of 3 km far away from the non-grazed sites. Aboveground litter decomposition of three dominant species (namely, Agropyron intermedium, Hordeum bulbosum and Juncus sp.) was studied using a litter bag experiment under field conditions. The impact of grazing conditions on soil pH was significant, but inconsistent. Grazed and ungrazed practices were similar in their effect on soil bulk density. Soil C and total N concentrations did not vary between treatments, while extractable P and available K contents were higher at non-grazed sites. The C and N pools were similar for both grazed and non-grazed sites. The C/N ratio of soil was significantly higher at the grazed site. Grazing conditions had no significant effect on litter decomposition rate of all species. The three pasture species, however, showed significant differences in litter decomposition rate. Thus, 16-year protection from grazing by sheep had no considerable impact on C and N sequestration in soil as compared with grazed site, however, plant nutrients inputs may increase as a result of increased herbage production under grazing exclusion conditions. In summary, significant differences occurred in litter decomposition may potentially affect C dynamics more than rangeland management practices.