نوع مقاله : پژوهشی
نویسندگان
1 بخش علوم و مهندسی خاک، دانشکده کشاورزی، دانشگاه شیراز، شیراز، ایران
2 بخش مهندسی بیوسیستم، دانشکده کشاورزی، دانشگاه شیراز، شیراز، ایران
چکیده
کلیدواژهها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
Introduction and Goals
Land management and land use change significantly affect soil status and related indicators, including the quantity and quality of soil fertility, as well as soil microbial biomass and respiration. Different methods of land use and management produce different amounts of plant residues of different quality. The diversity of these plant residues creates differences in the composition and function of soil microbial communities and the soil biological and fertility indices, and affects them. Land use change can remarkably affect various soil characteristics, soil quality and related indicators. Therefore, given that no systematic research has been conducted on the effect of land use type on soil biological and fertility indices in calcareous soils of Fars province, and there is an obvious necessity to cover this issue, this study was conducted to evaluate the status of some biological and fertility indices in calcareous soils in different land uses in a part of Fars province.
Materials and Methods
The soil samples were collected from 300 points located in the cities located in the center and northern half of Fars province and from a depth of 0 to 30 cm in four land uses, including forest, agriculture, strong rangeland, and poor rangeland between May and July 2019.
The samples after collecting from each sampling point, were placed in plastic bags and transported to the laboratory after labeling and air-dried, and passed through a sieve with a two mm opening diameter for further analysis and measurements. Then, some indices related to soil biological degradation and fertility, including organic matter, micronutrients, and microbial respiration, were measured using standard methods. The normality of the data distribution was examined using the Kolmogorov-Smirnov statistical test. The data were subjected to one-way analysis of variance (ANOVA) in a completely randomized design using the SPSS software. To compare the mean values of the studied soil properties among the studied land uses, mean comparison was also performed using Duncan's multiple range test at the probability level of 5%.
Results and Discussion
The results showed that there is a significant difference between the levels of manganese, copper, iron, organic matter, and basic soil respiration in the studied land uses. The levels of iron, copper, zinc, sodium, organic matter, and microbial respiration in agricultural lands were higher than in poor Rangeland lands, which could be due to the use of chemical fertilizers in these lands. Also, in lands with good vegetation cover, the levels of organic matter and micronutrients are higher due to the greater return of organic matter to the soil and the increased rate of organic matter decomposition. Also, in agricultural soils, the secretion of organic acids from the plant roots increases the solubility and absorbable form of these elements in the soil due to the formation of chelates with trace elements in the soil. In forest lands, more organic matter is stored in the soil with the fall of plant branches and leaves, while in other land uses, the amount of organic matter returned to the soil is much lower. In other words, this change in the amount of organic matter in different land uses is related to the amount of input and removal of organic matter in each land use, so that in the forest lands the amount of organic matter entering the soil is high and the amount of removal (exit) is lower. Such that the highest amount of organic matter (3.45%) was observed in forest land use, while the lowest amount of organic matter (1.64%) was found in rangelands with poor vegetation cover. This indicates the greater capacity of forest lands for carbon sequestration compared to lands of other land uses studied. Additionally, the results showed that the highest microbial respiration in the soil was observed in agricultural land uses (20.10 mg CO2/g per day) and forest land (20.02 mg CO2/g per day), while the lowest soil respiration was found in weak rangelands (12.40 mg CO2/g per day), which follows the pattern of changes in organic matter. Soil respiration is one of the climate-dependent characteristics, and high organic matter, the addition of new organic matter, and the diversity and abundance of microorganisms increase it.
Conclusion and Suggestions
The results showed that the amounts of iron, copper, zinc, sodium, organic matter, and microbial respiration in agricultural lands were higher than in poor rangelands, which could be due to the use of chemical fertilizers in these lands. Also, in lands with good vegetation cover, the amounts of organic matter and trace elements were higher due to the greater return of organic matter to the soil and the increased rate of organic matter decomposition. In general, land use change can affect different soil fertility and biological indices. Therefore, ignoring this issue can cause a decrease in yield in the short term, and ultimately, in the long term, natural resources will lose their usefulness. According to the results, the lands of poor rangelands, compared to other land uses, require more specific and well-structured management programs to improve, restore the potential of these soils and prevent existing soil degradation and soil fertility depletion, and reduce soil biological quality. In general, land type can affect various indicators related to biological degradation and soil fertility. Therefore, ignoring this issue can lead to a decrease in yield in the short term and, ultimately, in the long term, natural resources will lose their usefulness. According to the results, poor rangeland lands, compared to other land uses, require more specific and well-documented management programs to restore, restore the potential of these soils and prevent the process of existing soil degradation. It is recommended that continuous monitoring of lands exposed to more serious damage be carried out to examine the potential fertility and soil fertility, and to measure the downward trend and the rate of loss of productive power, and also use people to protect the lands.
کلیدواژهها [English]
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