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Information on inoculum load and diversity of native microbial community is an important prerequisite for crop management of microbial origin. Azospirillum has a proven role in benefiting the maize (Zea mays) crop in terms of nutrient (nitrogen) supply as well as plant growth enhancement. Bihar state has highest average national maize productivity although fertilizer consumption is minimum, indicating richness of Azospirillum both in terms of population and diversity in soils. An experiment was planned to generate basic information on Azospirillum population variation in maize soils under different agricultural practices and soil types of Bihar, to identify suitable agricultural practices supporting the target microorganism and efficient Azospirillum strain(s). No tillage, growing traditional maize cultivar, land use history (diara soil having history of maize cultivation), soil organic carbon (>1%) and intercrop with oat supported prevalence of Azospirillum in maize rhizosphere. Native Azospirillum population varied from 1 million to 1 billion/g soil under diverse agricultural practices and soil types. Such richness, however, does not necessarily mean that artificial inoculation of Azospirillum is not required in Bihar soils as 92% of Azospirillum isolates (50 isolates) were poor in nitrogen-fixing ability and 88% were poor on IAA production. Efficient strains of Azospirillum based on growth (three), acetylene reduction assay (three), IAA production (three), broad range of pH (two) and temperature tolerance were identified. The findings suggested that maize crop in Bihar should be inoculated in universal mode rather than site-specific mode.

On farm testing and frontline demonstrations were conducted during the years 2010 and 2011 under mandatory work of Krishi Vigyan Kendra, Seoni district of Madhya Pradesh. The status of soil nutrients, their depletion and build-up and crop productivity after two years under various combinations of fertilizer dose and manures on sandy clay was studied. The differences in the values of organic carbon available N, P and K in soil at 20 cm depth and crop productivity were found to be very marked. The data on yield show that the application of balanced fertilizer dose of N P and K as per STCR treatment with or without farm yard manure @ 2.5t/ha helped in sustaining the yield of rice at higher level over the years. The inclusion of FYM in the treatment schedule maintaining the organic carbon status and available N, P and K in soil thereby, sustaining the soil health. The under dosing of plant nutrients (Farmers practice) has caused a depletion in the available nutrients status of soil. The status of available K in soil was found to decrease in all the treatments but the decrease was of lower magnitude indicating the need to raise the level of K fertilizer application to meet the demand of the crops.