نوع مقاله : مقاله پژوهشی
نویسندگان
1 گروه علوم و مهندسی خاک، دانشکده کشاورزی، دانشگاه شهرکرد
2 گروه علوم و مهندسی خاک، دانشکده کشاورزی دانشگاه شهرکرد
3 گروه علوم و مهندسی خاک، دانشکده کشاورزی، دانشگاه شهرکرد، شهرکرد، ایران
4 گروه علوم و مهندسی خاک، دانشکده کشاورزی، دانشگاه ولیعصر رفسنجان، رفسنجان، ایران
چکیده
کلیدواژهها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
Conversion of desert soils to cropland may cause changes in some soil properties. The objective of this study was to analyze the effects of converting desert soils to cropland (wheat) and orchard (pistachio) on the soil organic carbon (SOC) content and storage, particulate organic carbon in Abarkooh region (Yazd province). Three land uses included wheat, pistachio, and desert soils were assessed. In order to compare the soil properties in different land uses, In September 2018, soil samples from desert, wheat, and orchard sites were taken from 0–20 and 20–40 cm depths. From each depth, 10 composite soil samples were taken. After pretreatments of soil samples, the soil properties including electrical conductivity, pH, gravel, sand, silt, clay, bulk density, organic carbon, calcium carbonate, were measured according to standard protocols. According to the obtained results, bulk density, gravel content and electrical conductivity decreased after the cultivation of desert soils. The SOC contents in the croplands and orchard were about 3.4-5.8 times higher than those in the desert soils. Also, the results showed an increase of 5.7 to 15.8 times of soil particulate organic carbon in the wheat fields and pistachio orchards compared to desert soils. The lowest SOC storage was observed in desert soils (0.19-0.24 kg.m-2) and the highest was obtained in pistachio orchards (1.08-1.12 kg.m-2). According to the findings of this study, it seems that sustainable cultivation and irrigation of desert soils could be an appropriate method which considerably enhances soil organic carbon sequestration in the study area.
کلیدواژهها [English]
Effects of land use/land cover changes on soil organic carbon stocks in Abarkooh region (Yazd province)
EXTENDED ABSTRACT
Soil organic carbon sequestration is a process by which atmospheric CO2 is stored in the soil. Desert soils cover approximately 35% of the Earth's surface and have attracted the attention of the scientific community in recent years because they can store large amounts of CO2, reduce the gap in lost carbon, and play a positive role in reducing climate warming. However, available data regarding soil organic carbon stocks of desert and the cultivated desert soils in central Iran is scarce. Therefore, the purpose of this research was to investigate the effects of converting desert soils into agriculture (wheat and pistachio) on the amount of soil organic carbon, particulate organic carbon and carbon sequestration in Abarkooh region (Yazd province).
For this purpose, three land uses included wheat, pistachio, and desert soils were assessed. In order to compare the soil properties in different land uses, 10 composite soil samples from two layers (0‒20 and 20‒40 cm) were collected from each land uses. Then, the soil samples were collected for laboratory analyses. The soil properties including electrical conductivity, pH, gravel, sand, silt, clay, bulk density, organic carbon, particulate organic carbon and calcium carbonate were measured according to standard protocols. The effect of cultivation of desert soils on soil properties was determined by one-way analysis of variance (ANOVA) and means were compared by Tukey test.
The results showed that bulk density, gravel content and electrical conductivity decreased after the cultivation of desert soils. At a depth of 0‒20 cm, the amounts of organic carbon of desert, wheat and pistachio soils were 0.09, 0.33 and 0.43%, respectively. These values for depth of 20‒40 cm were 0.07, 0.24 and 0.41%, respectively. Amount of particulate organic carbon was greater in wheat (0.11‒0.14%) and pistachio (0.22‒0.25%) than of the desert soils (0.01‒0.02%). The lower organic carbon contents in desert soils may partly be attributed to reduced plant residues input to the soil because of high soil salinity, low soil moisture and scarce vegetation cover. The contents of soil organic carbon and particulate organic carbon in croplands were about 3.4‒5.8 and 5.7‒15.8 times higher than those of desert soils, respectively. The greater increase of particulate organic carbon than soil organic carbon may be due to the application of animal manure and the addition of plant residues in cropland and orchard. The lowest organic carbon storage amount was observed in desert soils (0.19‒0.24 kg.m-2) and the highest was obtained in pistachio orchards (1.08‒1.12 kg.m-2).
The soil organic carbon is a very important characteristic for studying soil quality and it is also a main source for atmospheric CO2. Conversion of the desert soils to cropland may cause changes some soil properties. Therefore, this study was conducted to determine the effects of converting desert soils to cropland (wheat and pistachio) on the soil organic carbon content and storage, particulate organic carbon and organic carbon sequestration in central Iran. The positive impacts of cultivation, irrigation and fertilization of desert soils led to enhancement soil organic carbon, particulate organic carbon and soil organic carbon sequestration. Economic value of soil carbon sequestration in wheat fields and pistachio orchards were 1.08 and 2.07 million dollars, respectively. Based on this, knowing the changes in soil organic carbon reserves to evaluate the effects of desert soils conversion into cultivated soils can be important in sustainable land use management, especially in dry areas of the country. We suggest that the effects of desert soils conversion into agriculture soils should be studied along with its impacts on other elements of desert ecosystem like erosion and sustainable ground water table.