نوع مقاله : پژوهشی
نویسندگان
1 دانشجوی دکتری بخش علوم و مهندسی خاک، دانشکده کشاورزی، دانشگاه شیراز، شیراز، ایران
2 استاد بخش علوم و مهندسی خاک، دانشکده کشاورزی، دانشگاه شیراز، شیراز، ایران
3 دانشیار بخش مهندسی بیوسیستم، دانشکده کشاورزی، دانشگاه شیراز، شیراز، ایران
چکیده
کلیدواژهها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
Introduction and Goal
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. Due to the application of various management methods and land use, different size of plant residues and different quality are produced, and the diversity of characteristics of these plant residues effect the composition, function of soil microbial communities, various biological indicators, soil fertility and soil quality. On the other hand, land use change also affects various soil characteristics, soil quality and related indicators. In this regard, based on the results of documented research, the effect of land use type on the status biological indicators and soil fertility in calcareous soils of Fars province has not been investigated, and the need to conduct such research is essential. Therefore, this study aimed to evaluate the status of some biological and fertility indicators in calcareous soils in different land uses in a part of Fars Province.
Materials and Methods
In this study, soil samples were taken from 300 points located located in the central and northern half of Fars province. These samples were collected from May to July 2019 from a depth of 0 to 30 cm in four land uses, including forest, agriculture, strong rangeland, and poor rangeland. Samples taken from each point, were transported into plastic bags and, after labeling, sent to the laboratory. Then, for chemical analysis and measurement of the desired properties, they were air-dried, and passed through a sieve with a two mm opening diameter. In addition, in these samples, some biological and soil fertility indicators, including organic matter, trace elements, and soil microbial respiration, were measured using standard conventional methods. In this study, the normality of the data distribution was examined using the Kolmogorov-Smirnov statistical test. One-way analysis of variance (ANOVA) of the data was performed in a completely randomized design using the SPSS software. To the significance of the difference in the mean size of the studied soil properties among the considered land uses, the comparison of mean was also performed using Duncan's multiple range test at the probability level of 5%.
Results and Discussion
The results of this study showed that the difference in the manganese, copper, iron, organic matter, and basic soil respiration indices were significant among the studied land uses. The indices related to the amount of iron, copper, zinc, sodium, organic matter, and microbial respiration in agricultural lands were higher than in poor rangeland lands. The reason for this finding was 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. Also, in agricultural soils, duo to the secretion of organic acids from the plant rootsand formation of chelates with trace elements in the soil the solubility and absorbable form of these elements in the soil increased. In forest lands, more organic matter was stored in the soil as leaves and branches of the plant fell. While in other uses, the amount of organic matter returned to the soil was much lower. In other words, this change in the amount of organic matter in different land uses was related to the amount of input and removal of organic matter in each land use, such that in forest lands the amount of organic matter entering the soil is high and the amount of removal (exit) is lower. The highest amount of organic matter (3.45%) was observed in forest soil and the lowest amount of organic matter (1.64%) was found in rangelands with poor vegetation cover. This finding indicated the greater capacity of forest lands for carbon sequestration compared to lands of other land uses studied. Additionally, the highest soil microbial respiration was observed in agricultural (20.10 mg CO2/g per day) and forest land (20.02 mg CO2/g per day), and the lowest soil respiration was found in poor rangelands (12.40 mg CO2/g per day), which was a function of organic matter change pattern. Soil respiration is a climate-dependent characteristic, and it is increased by high organic matter, the addition of new organic matter, and the diversity and abundance of microorganisms.
Conclusion and Suggestions
The results of the study of biological and soil fertility indicators in the various land uses studied showed that, in general, the type and change of land use and, as a result, changes in the conditions or methods of land management and management operations can significantly affect various indicators related to biological status and soil fertility. Therefore, ignoring the type of land can lead to a decrease in yield in the short term and ultimately to a loss of natural resource utilization in the long term. According to the results, poor rangeland lands, compared to other land uses, require more specific and well-documented management programs to restore them, prevent the process of destruction, reduce fertility and biological quality, and restore soil potential. In this regard, it is recommended that serious and continuous monitoring of vulnerable lands be carried out to examine the potential fertility and soil fertility, and to measure declining trend and the speed of loss of productive power. It is also suggested that, along with implementing coordinated and documented programs and raising public awareness, people's forces be utilized to protect the lands.
کلیدواژهها [English]
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