Context Rice-based cropping system is a key for food security in the Indian subcontinent. However, the productivity of such systems has declined continuously due to deterioration in soil quality. The present study was carried out to identify key soil quality indicators and to develop indices of soil quality under long-term rice-based cropping systems in the hot sub-humid eco-region (HSE) of India. Methods Surface soil samples were collected from farmers’ field from two soil orders (Vertisols and Inceptisols) and with four long-term rice-based cropping systems: (1) rice-wheat (RW); (2) rice-chickpea (RC); (3) rice-lathyrus (RL); and (4) rice-fallow (RF). A minimum data set (MDS) of 24 soils attributes were screened to identify soil quality indicators using principal components analysis (PCA), and soil quality index (SQI) was determined. Key results The MDS indicators (in descending order of sensitivity) are field capacity (FC) (35.4%) followed by pH (30.5%) > porosity (13.6%) > potentially mineralisable carbon (PMC) (11.8%) > available boron (AB) (8.7%). Soil moisture content under FC was found as the most sensitive indicator affecting soil quality and rice equivalent yields (REY). The SQI of Vertisols (0.83) was significantly higher (P < 0.05) than Inceptisols (0.73). SQI under RC (0.86) cropping systems was significantly higher than RL (0.81), RW (0.76) and RF (0.78) (P < 0.05). Conclusions The inclusion of legumes (chickpea and lathyrus) into cropping systems sustained better soil quality and productivity. Implications SQI is not only useful for assessing soil health but also provides indicators of best-bet management practices for sustaining intensive cultivation.

Inclusion of a legume crop in a cropping system can improve soil physical and chemical properties, particularly in predominantly rice cultivating areas. Analysis of Variance (ANOVA) was performed between different soils and cropping systems to evaluate soil physical and chemical properties in Balod District of Chhattisgarh state of India. Among the soils, inVertisols, bulk density (BD) (p = .024), hydraulic conductivity (HC) (p < .005), available Fe (p < .005), available Mn (p < .005), available Zn (p < .005) and available B (p < .005) were found to be significantly lower than that of Inceptisols. However, significantly higher for porosity (p = .040), field capacity (FC) (p < .005), wilting point (WP) (p < .005), water holding capacity (WHC) (p < .005), mean weight diameter (MWD) (p < .005), soil pH (p < .005), electrical conductivity (EC) (p < .005), organic carbon (OC) (p < .005), available N (p < .005), available P (p < .005), available K (p < .005) and available S (p < .005). Tukey’s post-hoc test for multiple comparisons indicated that BD was found significantly higher for soils under rice-wheat (RW) cropping system, than that of soils under rice-chickpea (RC) (p < .005), rice-lathyrus (RL) (p < .005), and rice-fallow (RF) (p = .032). However, other soil properties i.e. porosity, FC, WP, WHC, HC, MWD, soil pH, OC, available N, available P, available K, available S, and available Zn were found significantly higher for soils under rice-legume cropping system (RC and RL), than that of soils under RW and RL. Thus, from the study, it is concluded that inclusion of legumes into cropping systems maintained better soil physical and chemical properties and helpful to work out the best management practices for sustaining intensive cultivation.

The present study aimed to evaluate the nutrient budget, apparent nutrient balance and quantify nutrient depletion and build-up resulting from 25 years of long term fertilization in a Vertisol of Subtropical India. The 150 % NPK recorded maximum positive apparent nitrogen (N) (3038 kg ha-1) and phosphorus (P) (1182 kg ha-1) balance, while minimum was recorded with absolute control (-1604 kg ha-1). The inclusion of green manure (GM) with 50 % NPK registered positive apparent N balance. The apparent P balance was positive with inclusion of P in fertilizer scheduling even under 50 % NPK and 50 % NPK + Blue green algae (BGA) treatments, indicating that 50 % P application fulfilled the crop P demand. The negative apparent K balance was recorded across almost all treatments with the average rate of -181 kg ha-1 yr-1 indicating luxury consumption of K by crops than its supplementation. The soil available N was depleted in all the treatments, however, depletion was minimum under 150 % NPK (10 kg ha-1) and 100 % NPK+FYM (13 kg ha-1). There was build-up of soil available P over initial status in all the imposed treatments (from 5 to 18 kg ha-1) even under sub-optimal dose of NPK, except in absolute control and 100 % N. However, a net negative soil available K was observed in almost all the treatments due to mining of soil K reserves to meet out crop demand. The findings underscore the critical necessity for strategic N and K fertilization in Vertisol under rice-wheat cropping system to sustain optimal nutrient equilibrium, managing soil fertility and maximize agronomic productivity.