Vol. 12, Issue 1 (2023)

Author(s):
Pradeep, Krishna Murthy R, Subbarayappa CT, Prakasha HC, Devakumar AS and Muthuraju R

Abstract:
Quantitative assessment of soil quality is required to determine the sustainability of land uses in terms of environmental quality and plant productivity. Our objective was to identify the most appropriate soil quality indicators and to evaluate the impact of different land use systems (Natural forest (Mixed), Teak land use system, Mango land use system, Guava land use system, Finger millet–chemical fertilizer based cropping system (FM-CF), Finger millet–organic manure based cropping system (FM-OM), Finger millet–integrated nutrient management based cropping system (FM-INM), Custard apple land use system, Amla land use system, Melia dubia land use system) on soil quality in Gandhi Krishi Vigyana Kendra, Bengaluru. We collected 100 soil samples (30 cm depth) and analyzed them for 32 soil attributes (physical, chemical, biological, total carbon, microbial biomass carbon and carbon pools). For selection of soil quality indicators, principal component analysis (PCA) was performed on the measured attributes, which provided five principal components (PC) with eigenvalues >1 and explaining at least 5% of the variance in dataset. The five PCs together explained 92.77% of the total variance. Based on rotated factor loadings of soil attributes, selected indicators were: SiPCP (Silt passive carbon pool) from PC-1, soil porosity from PC-2, available potassium from PC-3, silt content from PC-4 and soil pH from PC-5. Indicators were transformed into scores (linear scoring method) and soil quality index (SQI) was determined, on a scale of 0–1, using the weighting factors obtained from PCA. SQI rating was the highest for the least-disturbed sites, i.e., natural forest (Mixed) land use system (0.96) and teak land use system (0.73). The lowest for the agriculture sites, i.e., FM-CF (0.38). Ratings for the other land uses systems were Melia dubia land use system (0.70)> Mango land use system (0.67)> Guava land use system (0.64)>Custard apple land use system (0.62)>Amla land use system (0.60)>FM-INM (0.58)>FM-OM (0.53). Overall contribution (in percent) of the indicators in determination of SQI was in the order: SiPCP (57.39%)>soil porosity (21.02%)>available K (9.51%)>silt content (6.21%)>soil pH (5.88%). Results of this study suggest SiPCP and soil porosity as the two most powerful indicators of soil quality in study area. Thus, silt passive carbon pool and soil porosity management holds the key to improve soil quality under different land use systems.