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Degradation of soil quality caused by conventional tillage practices is a major concern for the sustainability of rice-wheat cropping systems in South Asian region. Therefore, suitable conservation agriculture (CA) practices are required. This study investigates the stratification and storage of soil organic carbon (SOC) and total nitrogen (TN) as affected by eight years of different CA practices in the North-West Indo-Gangetic Plains of India. There were four treatments: (1) conventionally tilled rice-wheat cropping system, (2) reduced-till CA-based rice-wheat-mungbean system, (3) no-till CA-based rice-wheat-mungbean system, and (4) no-till CA-based maize-wheat-mungbean system. The mean stratification ratio (SR) (i.e. a ratio of the concentrations of SOC and TN in the soil surface to those in a deeper layer) of SOC and TN for 0–5:5–10, 10–15, 15–20, 20–25 and 25–30 cm were found higher (> 2) under CA practices compared to intensive tillage-based conventional agricultural practice (< 2). No-till CA-based rice-wheat-mungbean system stored the highest amount of SOC (25.32 Mg ha−1) whereas reduced till CA-based rice-wheat-mungbean system stored highest amount of TN (3.21 Mg ha−1) at 0–30 cm soil depth. This study shows that CA stratifies SOC and TN and helps to enhance SOC sequestration and soil quality. [ABSTRACT FROM AUTHOR]

Seventeen azide resistant mutants were isolated from six strains (103, HT-54, HT-54 (2), 10P, E-12 and MSX 9) of Azotobacter chroococcum. All the parent strains were tested for their minimal inhibitory concentration (MIC) by growing cells in liquid medium containing different concentrations of sodium azide (5 μ gml1 to 200 μ gml1). The strains showed different MIC values indicating that the resistance pattern varied with each individual strain. These azide resistant mutants were assessed for their performance on two cotton cultivars- Gossypium hirsutum, var. H- 117 and Gossypiun herbaceum var. HD-123 under pothouse conditions for various plant parameters. Inoculation of cotton seed with Azotobacter mutants showed better results than inoculation with their respective parental strains. Azide resistant mutants showed increased plant height, early flowering, more yield, high biomass and high total nitrogen content. Better performance by these mutants might be due to high indole acetic acid, ammonia excretion and high nitrogenase activity. [ABSTRACT FROM AUTHOR]