Changes in Soil Properties and Microbial Indices across Various Management Sites in the Mountain Environments of Azad Jammu and Kashmir

Abstract

The mountainous region of the Himalayas is covered with forest, grassland, and arable land, but the variation in ecosystem functions has not been fully explored because of the lack of available data. This study appraises the changes in soil properties over the course of a year (spring, summer, autumn, winter) for forest, grassland, and arable soils in a typical hilly and mountainous region of Azad Jammu and Kashmir, Pakistan. Soil samples were collected from major land-cover types in the mountain region: natural forest, grassland, and cultivated land (arable). The natural forest served as a control against which changes in soil properties resulting from removal of natural vegetation and cultivation of soil were assessed. Soil samples were collected from depths of 0–15 and 15–30 cm six times during the year and examined for changes in temperature, moisture, electrical conductivity (EC), micronutrients [iron, manganese, copper, and zinc (Fe, Mn, Cu, Zn, respectively)], and microbial population. Significant differences were found in soil temperature, soil moisture, Fe, Mn, Cu, Zn, and number of bacteria, actinomycetes, and fungi among the three land-cover types. Soil under cultivation had 4–5 °C higher temperature and 3–6% lower moisture than the adjacent soils under grassland and forest. Electrical conductivity (EC) values of forest, grassland, and arable soil were 0.36, 0.30, and 0.31 dS m⁻¹, indicating that soil collected from the forest had 18–20% more EC than the adjacent arable and grassland soils. On average, amounts of Fe, Mn, Cu, and Zn in the soil collected from the arable site were 6.6, 5.7, 1.7, and 0.8 mg kg⁻¹, compared with 24.0, 12.1, 3.5, and 1.2 mg kg⁻¹ soil in the forest soil, showing that arable had two to four times less micronutrients than grassland and forest. Populations of bacteria, actinomycetes, and fungi in the forest were 22.3 (10⁵), 8.2 (10⁵), and 2.5 (10³), respectively, while arable land exhibited 8.2 (10⁵), 3.2 (10⁵), and 0.87 (10³). Season (temperature) and depth showed significant effects on microbial activity and nutrient concentration, and both decreased significantly in winter and in the subsurface layer of 15−30 cm. Different contents of the parameters among arable, grassland, and forest soils indicated an extractive effect of cultivation and agricultural practices on soil. Natural vegetation appeared to be a main contributor to soil quality as it maintained the moisture content and increased the nutrient status and microbial growth of soil. Therefore, it is important to sustain high-altitude ecosystems and reinstate the degraded lands in the mountain region.

Keywords:

• Land degradation
• microbial activity
• micronutrients
• soil properties
• soil quality
• soil type

Acknowledgments

We thank Dr. Muhammad Aslam of Soil Biology and Biochemistry Section, Institute of Natural Resources and Environmental Sciences, National Agriculture Research Center (NARC), Islamabad, Pakistan, for providing all analytical facilities in their laboratory during this study.