اثرپذیری ویژگی‌های بیولوژیک خاک مرتع در مواجهه با تغییر کاربری به دیمزار(مطالعه موردی: مراتع کرمانشاه)

پژوهش حاضر با هدف بررسی اثرپذیری ویژگی‌های بیولوژیک خاک مرتع در برابر تغییر کاربری به دیمزار در سه محدوده قلعه، چشمه‌قادر و محمودآباد کرمانشاه صورت گرفت. بدین منظور در هر محدوده، دو تیمار دیمزار و مرتع انتخاب شد و ویژگی‌های بیولوژیک خاک اندازه‌گیری گردیده و با استفاده از آزمون تی‎استیودنت مستقل مقایسه شد. نتایج نشان داد حداکثر و حداقل میزان تنفس پایه خاک به‌ترتیب در دیمزار قلعه و مرتع چشمه‌قادر بود. میزان تنفس برانگیخته در مراتع چشمه‌قادر، قلعه و محمودآباد به‌ترتیب 98.27 و 95.97 و 87.63 و در دیمزار 92.57، 86.47 و 81.97 میلی‌گرم در کیلوگرم اندازه‌گیری شد. کربن زیست توده میکروبی در مراتع قلعه، چشمه‌قادر و محمودآباد به‌ترتیب 189، 197 و 181 و در دیمزار 191، 155 و 181 میلی‌گرم در کیلوگرم اندازه‌گیری شد. بیشترین و کمترین میزان نیتروژن زیست توده میکروبی به‌ترتیب در مرتع چشمه‌قادر (13میلی‌گرم در کیلوگرم) و دیمزارها محمودآباد ( 5.77 میلی‌گرم در کیلوگرم) حاصل آمد. ضریب متابولیکی میکروبی در دیمزار قلعه، چشمه‌قادر و محمودآباد به‌ترتیب 5.12، 3.96 و 5 میلی‌گرم در کیلوگرم بود که در مرتع به‌ترتیب به 3.21، 2.83 و 3.52 کاهش یافت. براساس نتایج، پارامترهای تنفس پایه خاک، کربن زیست توده میکروبی، نیتروژن زیست توده میکروبی، نیتروژن زیست توده میکروبی به نیتروژن کل و ضریب متابولیکی میکروبی در سطح 0.01 و پارامترهای تنفس بر انگیخته و شاخص قابلیت دسترسی کربن در سطح 0.05 تغییرات معنی‌داری داشتند. بنابراین اتخاذ شیوه‌های مناسب برای کاهش اثرات منفی تغییر کاربری مراتع به اراضی کشاورزی بر سلامت خاک در بلندمدت بسیار مهم است. 

effectiveness of biological characteristics of rangeland soil in the face of land use change to dryland (case study: rangelands in kermanshah)

1- introductionchanging the use of rangeland to agriculture is a significant process in land and natural resource management. this practice has gained increased attention in recent years due to the growing global demand for food and agricultural products. while this land-use change can potentially address food security concerns, it also poses environmental challenges and consequences. these include damage to natural ecosystems, soil degradation, biodiversity loss, and climate change. therefore, a thorough understanding of both the benefits and drawbacks of this transition is crucial to ensure sustainable growth and the conservation of natural resources. the present study aimed to investigate the impact of land-use change from rangeland to dryland agriculture on the biological characteristics of rangeland soil in a specific region of kermanshah. 2-methodologyin this study, several including as basic soil respiration, stimulated respiration, microbial biomass carbon, microbial biomass nitrogen, carbon to nitrogen ratio of microbial biomass, microbial ratio, microbial metabolic coefficient and carbon availability index were measured. after the sampling and laboratory examinations, one-way analysis of variance (anova) was used to compare the soil characteristics in two land use of rangeland and rainfed agricultural land in the three areas of qala, cheshme qadir and mahmoud abad region. moreover, duncan’s test was employed in spss software to compare the mean of biological parameters.3- results the results showed that the highest amount of basic soil respiration was recorded in the dry agricultural use of qala area with the amount of 78.3 mg/kg of dry soil and the lowest amount was recorded in the rangeland use of cheshme qadir area. the amount of stimulated respiration was measured in rangeland land use in two areas of cheshme qadir and qala, 27.98 and 95.97, respectively, and in dryland land use, 57.92 and 86.47 mg/kg of dry soil were measured. meanwhile, in mahmoud abad area, the stimulated respiration of soil in the dryland agricultural use was more than that of the rangeland land, and its amount was measured at 87.63 mg/kg dry soil in the dry land land use and 81.97 mg/kg in the rangeland land use. the carbon values of microbial biomass were measured in three areas of qala, cheshme qadir and mahmood abad in rangeland land, respectively 189, 197 and 181, and in agricultural land, 191, 155 and 181 mg of carbon per kilogram of soil, respectively. the highest amount of microbial biomass nitrogen among rangeland uses among the three studied areas was measured in cheshme qadir rangeland with a value of 13.60 mg per kilogram of dry matter. the lowest amount was also obtained in the agricultural use of mahmoud abad region with the amount of 5.77 mg per kilogram of dry bark. nitrogen values of microbial biomass to total nitrogen were measured in the three areas of qala, cheshme qadir and mahmoodabad, respectively, 28.09, 26.92, and 36.25 in rangeland land use, and also in agricultural land use, 22.70, 24.49, respectively. and it was 33.31 and the ratio of carbon to nitrogen of microbial biomass was almost equal in all the studied areas in both studied uses. also, the highest amount of microbial ratio was measured in agricultural use of cheshme qadir area with 0.78 mg/kg of soil. the values of microbial metabolic coefficient were measured in three areas of qala, cheshme qadir and mahmoodabad, respectively, 5.12, 3.96 and 5 mg/kg of soil in agricultural use, and in rangeland use it was 3.21, 2.83 and 2.83, respectively. it decreased by 3.52 and the results showed that the value of carbon availability index was higher in agricultural use than rangeland use4- discussion & conclusionsbased on the results obtained from the present research, the conversion of land from rangelands to rainfed land causes a change in the basic soil respiration parameters, microbial biomass carbon, microbial biomass nitrogen, microbial biomass nitrogen to total nitrogen and microbial metabolic coefficient at a significant level of 1%. confidence factor was 99 percent). also, the parameters of stimulated respiration and the index of carbon availability were changed with the conversion of rangeland to dryland with a significant level of 5% (95% confidence coefficient). the parameters of carbon to nitrogen ratio of microbial biomass and microbial ratio did not change significantly. accordingly, it can be acknowledged that the conversion of rangeland to agriculture significantly changes the biological properties of the soil. while it can lead to increased productivity, it is important to adopt sustainable practices to minimize negative impacts on soil health and maintain its long-term.