Soil properties and soil microbial biomass along elevation gradient in rainfed agroecosystem in Kaski district, Nepal

Abstract

Soil is important natural resources for the sustenance of life on the earth and also a crucial part of agriculture. The study was conducted to examine the soil physicochemical properties and microbial biomass carbon along elevation gradient in rainfed agroecosystem at Annapurna Rural Municipality Ward No.10, Kleu (1350) and Annapurna Rural Municipality Ward No.11(1650 - Jhinu danda, 1950 - Taulung and 2250 - Chhomorong) Kaski, Nepal. Altogether 60 composite soil samples were sampled from different elevation gradient. Soil samples were collected from depth layer 0-10cm, 10-20cm and 20-30cm by using soil corer. At each elevational point 5 plot of 10m ×10m was made with the distance of 15-50m between each plot. Each elevation gradient distance was apart 300m. Random sampling method was used to collect the samples. The result of the study shows that soil physical (soil temperature, soil textural fractions, moisture, and bulk density) chemical (pH, electrical conductivity, soil organic carbon, soil organic matter, soil organic carbon stock, total nitrogen, available phosphorous, available potassium) and biological (microbial biomass carbon) properties varied significantly with different elevation gradient and soil depths. The soil in the study region was mildly acidic to almost neutral. Loamy sand was the textural class observed. The bulk density, soil temperature and silt content were recorded greater in the lower elevation. The increasing trend in the Moisture, EC, SOC, SOM, SOC stock, TN, AP, AK, clay, sand and MBC along increasing the elevation gradient and decreasing trend in the soil depth 0-10cm to 10-20cm and 20-30cm whereas bulk density and pH was increase with increasing soil depth layers. The silt content and soil temperature were decreased with increasing the soil layer. All the nutrients, SOC and microbial biomass carbon were greater at elevation 2250masl. Soil quality index values were fair in all the elevation with depth, although the value was decreased with depth. At the depth 010cm, MBC has positive significant correlation with SOC, Soc stock, AK,

and sand and negative significant correlation with temperature and silt. Similarly in the depth 1020cm MBC has positive significant correlation with SOC, Soc stock, AP and clay and

likewise in the depth 20-30cm, no significant correlation was found with SMBC.

Keywords: Rainfed land, physicochemical properties, microbial biomass carbon, soil quality index