Soil type and land use influence biological functioning of arid soils

Abstract

Land-use change affects soil organic matter dynamics and biological functioning in dryland ecosystems, yet integrated evidence from Central Asian arid soils remains limited. This study evaluated changes in soil organic matter, nitrogen status, and biological activity in Haplic Kastanozem, Haplic Calcisol, and Gleyic Calcisol of the Zhambyl region, southern Kazakhstan, under virgin and arable land use. Soil samples (0–20 cm) were collected during spring, summer, and autumn. Soil organic matter content, nitrogen fractions, microbial abundance, FDA hydrolytic activity, soil respiration, plant residue decomposition, and integrated biological indices were determined. Data were analysed using three-way ANOVA and principal component analysis (PCA). Haplic Kastanozem maintained the highest soil organic matter (1.90–2.56 %) and total nitrogen (0.149–0.196 %) contents under virgin conditions, whereas cultivation reduced soil organic matter reserves to 1.42–1.57 %. Plant residue decomposition ranged from 7.28 % in arable Haplic Kastanozem to 74.37 % in irrigated Gleyic Calcisol. Seasonal mean IIBS ranged from 67.9 ± 9.67 to 97.5 ± 1.22. Soil type significantly affected all investigated indicators ( P  < 0.001), while PCA explained 57.0 % of the total variance. The findings indicate that arid soils differ in their biological functioning strategies under agricultural use. Integrated indicators provide a basis for soil-specific management aimed at sustaining soil fertility and ecosystem functioning in Central Asian drylands.