Title : Soil bacterial and fungal communities augmented by regenerative agriculture nurturing soil quality and plant health
Abstract:
Population, climate change, deteriorating soil conditions, increasing crop-pests, poor crop productivity, adverse impacts on environment and human health due to conventional-chemicalagriculture are among the wide-array of problems faced by India’s agriculturists. It is therefore imperative to identify and move towards agricultural methodologies that can help to overcome these situations. Regenerative agriculture (RA) which relies on environment-friendly practices for boosting soil and plant health holds this promise. There are limited reports from India on the impact of RA on crop and soil health. In recent times, few Indian farmers have adopted RA using modern and traditional methods to support soil and crop health and productivity. This study compared the soil under RA with conventional agriculture, barren soil and eucalyptus containing plots, for their bacterial, fungal and chemical profiles. We used 16S and ITS amplicon sequencebased analysis of soil DNA to respectively characterise the soil’s bacterial and fungal community structures and well established assays to determine the soil’s chemical profile. We considered two crops – Vegetables (Tomato/beans) and finger-millet for this study. We also recorded the effect of (≤3 years) short-term and (>5 years) long-term RA application on soil health. We found that RA, irrespective of the treatment used, enhances soil’s bacterial diversity and the levels of Plant Growth Promoting Rhizobacteria (PGPRs) in the soil. All RA plots showed adequate amounts of potassium, phosphorus, and all minor nutrients, except nitrogen. In a plot following >5 years of RA practice we observed Soil Organic Carbon (SOC) levels within the ideal range whereas all other plots showed lesser than ideal SOC levels. Interestingly, we also report the poorest soil bacterial profile in eucalyptus containing plots suggesting towards the detrimental impact of eucalyptus plantations on soil health. Fungal community in finger millet and vegetable RA plots showed high level of diversity as well as species evenness. In addition, RA plots in both crops showed a significant reduction in plant pathogenic fungal genera - Bipolaris and Pyrenochaetopsis. Further, the RA finger millet plots contained specific Plant Growth Promoting Fungi (PGPF) Rhizophlyctis and Agrocybe (saprotrophs) and Acrocalymma (biotic and abiotic stress tolerance and plant growth and yield inducer), which were absent in finger millet CA and BL plots. Similarly, in RA vegetable plots we found PGPFs including - Mortierella (a biocontrol agent and plant nutrient solubilizer), Phoma (bioherbicide and plant growth promoter) and Pseudorobillarda and Torula (saprotroph) which were absent in the vegetable CA plots and BL plots. We conclude that extended period of regenerative agriculture use is effective in supporting a more robust and heterogeneous population of bacteria and fungi which together improve the soil’s nutritive and plant health. Additionally, regenerative agriculture also boosts the soil’s SOC levels forming a significant means to mitigate climate change.
