Do soil horizons and land-uses screen different sets of soil quality indicators in the hilly region of northeast India?

Maintaining soil quality is crucial to achieving 'zero hunger', particularly in tropical climates, as described in 'Sustainable Development Goal 2' by the United Nations. This study aims to assess the effects of different land uses, including shifting or jhum cultivation (JC), abandoned jhum (AJ), plantation cropland (PC), teak plantation (TP), and settled cultivation (SC), on soil quality (SQ) in a warm per humid region in India. Soil samples were collected from the surface and subsurface horizons of the soil profile in twenty different locations, and fourteen different soil attributes were analyzed. The principal component analysis (PCA) and discriminant analysis (DA) were performed to obtain the normalized soil quality index (SQI) as well as to screen soil quality indicators for different soil horizons. In surface soils, the different soil quality classes were found as "high quality" (SQI > 0.65) in SC, "medium quality" (0.52 <= SQI <= 0.65) in JC, TP, and PC, and "low quality" (SQI < 0.52) in AJ. In subsurface soils, only two distinct classes of soil quality were obtained. Exchangeable Ca (Exch. Ca) with a high positive coefficient of 0.80 in discriminant function 1, was the most powerful indicator to monitor changes in SQ on the surface soil horizon. In the subsurface soil horizon (B1), Exch. Ca with a high positive coefficient of 1.2 in discriminant function 1 and Exch. Al with 0.85 in discriminant function 2, were found to be essential indicators. Whereas, Exch. Mg, with a high negative coefficient of - 1.01, was screened for deep subsurface soils (B2 horizon) under different land use. Overall, maintaining base saturation and reducing Exch. Al could be the key to maintaining and improving the soil resources of hilly terrain in Mizoram under various land uses in the northeastern region of India.