Impact of Different Farming Practices on Soil Nutrients and Functional Bacterial Guilds in Pigeonpea-Wheat Crop Rotation

Indiscriminate use of chemicals in agriculture impacts soil properties, significantly compromising microbial diversity. Therefore, integrating eco-friendly strategies with minimal adverse impact on soil microflora and increasing crop productivity are essential for sustainable agriculture. The study was designed to understand the impact of different farming practices on the rhizospheric bacterial populations involved in nitrogen and phosphorus cycles, soil nutrient contents, and the uptake of nutrients by plants. A 3-year field experiment was set up in a randomized block pattern with pigeonpea-wheat cropping system (PWCS). Conventional and organic farming management practices were selected with two sets of organic amendments (ORG1: farmyard manure, ORG2: leaf compost + crop residue), three sets of conventional treatment [CON1: farmyard manure + 50% NPK (nitrogen, phosphorus, and potassium), CON2: leaf compost + crop residue + 50% NPK, and CON3: 100% NPK], and control (C). Plants and soil were sampled at the harvest stage of the crops for three consecutive cropping seasons to assess the soil and plant nutrient contents, and N and P cycling bacterial guilds in the rhizospheres. The total NPK uptake by plants was higher in conventional treatments than in organic treatments for both the crops, compared to the control treatment. Bacterial genes involved in the N and P cycles positively correlated with organic farming practice in both crops. Overall, agricultural management strategies had a significant impact on PWCS. The amoA gene was the most sensitive marker contributing to the variation in the abundance of the functional bacterial community in response to agri-management practices. Soil and plant NPK content showed a significant positive correlation in the case of the pigeonpea crop. The study showed the positive effect of different organic amendments on rhizospheric bacterial guilds. The combination of organic amendments with reduced chemical fertilizers intensifies the functioning of the N and P cycles. Organic amendments and reduced chemical fertilizers in PWCS offer a promising avenue for improving nutrient cycling, enhancing soil health, and ultimately bolstering crop productivity.