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چکیده
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This study examined the impacts of long-term (47 years) exclosure, continuous grazing, rainfed wheat farming, mowing and seasonal grazing on soil properties, especially soil organic carbon (SOC) and total nitrogen (TN), in the cold semi-arid grasslands of Saral Research Station and Mangahol-Zardawan grasslands, Kurdistan, Iran. In this investigation, 180 soil samples were taken from 0-20 cm depth within an area of 1.0 hectare for each land use. Samples were collected in the four non-consecutive years of 2009, 2013, 2017 and 2021. Results showed that the value of SOC differed significantly among different land uses (P<0.01). SOC was highest in the seasonally grazed sites and the excluded areas in 2021 with 52,000 and 35,787 kg/ha respectively, while the rainfed wheat farming site had the lowest SOC. TN was also the highest at 4,200 kg/ha in the seasonally grazed area in 2021, while the lowest concentration of TN was recorded in the rainfed farming site. The highest and lowest C/N ratios were recorded in the excluded and rainfed wheat farming with 12.63 and 4.6 respectively. This suggests that, in grasslands with similar ecological conditions, seasonal grazing may be a viable alternative to either continuous grazing, rainfed wheat farming or mowing. Of the land uses examined, exclosure had advantages over wheat growing and year-round grazing, but SOC and TN benefits of exclosure were less clear for mowed and seasonally grazed areas. The role of exclosure in maintaining SOC and TN levels needs further comparative investigations of other land uses.
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