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Microbes – Facilitating resource recycling

Dhananjaya P. Singh and Renu 

Viable biological options that boost on-farm resource recycling and integrated management have great promise in minimizing threats of climate change on crop plants, losses due to indiscriminate use of agrochemicals and soil contamination due to organo-metal pollutants.


The exploitative nature of present day agriculture is solely based on promoting maximum soil performance through continued use of non-recyclable chemical farm-inputs. Such practices only consider soils as a matter of physical and chemical entities and largely ignore or avoid the most vital, vibrant and dynamic biological components through which many of the today’s agricultural problems can be resolved. This is why we need to advocate for a balanced chemistry and biology above- and below ground soils, that in support with the external environmental factors, determines plant performance in any agro-ecosystem. The adverse consequences of excessive chemical usage in agricultural system has forced farmers to explore alternative options for keeping soils live and responsive, failing which, there seems to be no return towards normalcy of a balanced agro-ecosystem. Microbe-driven agro-ecological practices therefore, can alternatively strengthen sustainability of the productive farms because of their prime focus on enriching biodiversity in the cultivated area.

Microbes and their beneficial interactions

Being major inhabitants of normal, sub-normal and extreme habitats, microbes are evolutionarily evolved with unique inherent capabilities of recycling, rehabilitating, managing and remediating their own habitats. By doing so, they have prospects of rejuvenating soil and plant health and supporting crop productivity if explored sensibly. Such microbes with specific functions and robust ecological strength, when developed as microbial inoculants (biofertilizers, biopesticides, microbial stimulants) can help manipulate soil ecology, rhizosphere biology and plant functions to obtain proven impact on crop growth and productivity under normal or even threatening developmental conditions. Therefore, developing microbial inoculants from a diverse population of microorganisms has multifaceted prospects for the farmers and agriculture as they live in continuum.

Demonstrating the bioconversion method

For the crops, microbial inoculants can fix nitrogen, solubilize and mobilize phosphorus, potassium, zinc and iron, chelate siderophores, produce phytohormones, perform carbon sequestration, mineralize nutrients, degrade recyclable residual agro-waste and remediate soil contaminants in an inevitable manner, silently and continuously. Beneficial interactions of microorganisms with the plant promote root growth, induce systemic resistance and/or tolerance against stresses, instigate innate immunity and modulate chemical biology of the rhizosphere (the living root zone in close vicinity of the soil). Dissemination of entwined information on the above aspects of microorganisms clubbed with their agro-ecological linkages and benefits among farming community can not only improve their understanding on microbial processes, plant responses and soil health but can lure them to adopt microbe-based practices as an supplementary alternative to external input-based farming system at their own farms.

Microbial inoculants interact with the crops to confer beneficial impacts under diverse edaphic, climatic and biophysical factors that affect soil performance and plant competence. Increasing farmer’s literacy and awareness on the understanding of microbial interactions with crop plants and their responses in the soils under stressed environment could pave the way for enhancing adoption of microbial technology at the ground in an unprecedented manner. Farmers may not be interested in the underlying mechanisms of the interactions, but they may certainly become keen to know about final results of interactions on crop productivity. This is why training them on the available viable biological options around them, mode of delivery via in planta and soil applications, quality aspects, viability issues, precautions and technological reliability always becomes regenerative among masses.

We have demonstrated microbe-mediated practices among more than 1200 farmers. They are trained and encouraged to use these inoculants for seed coating, inoculating them on the root surface of the seedlings, and time-lined application in the soils (prior to crop sowing, in the mid of the crop life and prior to 10 days of flowering).

Results

This integrated delivery mode in the rice, wheat and vegetables have shown qualitative and quantitative changes in the crop yield and produce quality. Many farmers are now frequently applying Bio-NPK and Zn microbial consortium for producing rice, wheat and vegetables. The use of bacterial consortium helped them to reduce application of NPK chemicals up to 30% in the farms in rice and wheat crops. Similarly, with the application of biopesticides like Trichoderma and Pseudomonas as seed and seedling inoculants and for soil application, the risk of soil borne diseases of chickpea and several vegetable crops was massively minimized in nurseries and at the farmers’ fields. Inoculant’s application enhanced almost 40% additional gain in the healthy nursery seedlings due to minimum loses from soil borne diseases of vegetables and also led to 7-10% enhancement in the crop produce.

To our surprise, many farmers who once used these bioproducts, returned to us in search of products and discussed many scientific aspects of the inoculants as to how they function in the soils. In the promotional programs sponsored by the Department of Science and Technology (DST), Government of India distributed the technical kits comprising booklets, bulletins and microbial consortia (both liquid and powder formulations), to encourage adoption. Later on the farmers themselves started obtaining these bio-products from State agriculture line departments or commercial product dealers in their regions.

Learning aptitude of the farmers has led us to explain multifaceted and diversified issues of cumulative understanding on the beneficial impact of microbial inoculants on crops. Sustainability aspects, viability concerns, strategic applications, techno-commercial issues and environmental prospects for maximizing field adoption of microbe-based practices for better crops and soils were also demonstrated. Efforts have been made to maximize large scale applications of microbial inoculants (individual or consortium) as a replacement for chemical inputs in cereals, oilseeds, pulses, sugarcane and vegetable crops.

Biocompost

Exhaustive crop production systems are devoid of soil organic matter (SOM) (<0.4-0.5%) and its regain is a difficult task until we look for the carbonaceous supplements. Soils that lack organic matter for long duration cannot support microbial life and thus, lose natural beneficial traits suitable for good agricultural practices. It therefore, becomes mandatory to make addition of organic matter to the soils for better performance. Addition of external farm yard manure (FYM) or cultivation of green manure crops like Sesbania and Crotalaria add to soil organic content. Even then, crop production based on chemical-inputs again restricts growth of beneficial life forms in the carbon depleted soils.

Throughout the country, chemical-input based cropping pattern produce agricultural residual matter in plenty in all cropping seasons. These residues, a large portion of which go waste, if recycled through microbial processes, can add to a lot of organic carbon. Thus, converting farm residues into compost through rapid microbe-mediated bioconversion practices again has a great promise. Not only this, the compost thus produced is further being enriched and fortified with the desired beneficial microbial consortium of nitrogen fixers, phosphate solubilizers, potassium and zinc mobilizers, iron chelators and phytohormone producers by simply incubating it over 15 to 20 days in the field. Now this bio-fortified compost has desired traits with customized applications.

This bioconversion method has been demonstrated among more than 3500 farmers from 30 villages in four districts of Eastern Uttar Pradesh namely Mau, Azamgarh, Ghazipur and Ballia.          Biocompost rich in nitrogen fixer and Zinc-rich microbes is being used in paddy crop and iron-rich microbe-based compost is becoming useful for vegetables, flowers and fruits. The raw compost may again be fortified with disease-controlling microbial species like Trichoderma (fungi), Pseudomonas and Bacillus (bacteria). Biocompost thus produced is now being promoted for producing seed- and soil-borne disease-free seedlings of commercial vegetables and saplings of forest plants. Alternatively, if adopted by a group of farmers or self help groups (SHGs), the practice of producing fortified and microbe-enriched compost can lead to entrepreneurial skilling among farmers for additional economic benefits.

Conclusion

Potential ecological benefits of farm-centric microbe-mediated approaches has been observed in terms of directly reducing farmer’s dependency on agricultural chemicals, minimizing cost on external inputs,  making soils more biologically viable and freshness in the produce of vegetables and fruits. It is also a win-win condition for farmers that the beneficial microbial inoculants, once introduced into the fields, can survive for longer time depending upon the availability of organic matter, minerals, moisture and conducive environment. Thus under supportive soil conditions, microbial inoculants can demonstrate their multipronged recycling capabilities to favor soil and plant health and maintain agro-ecology of the whole farm system.

Acknowledgements: Author is grateful to Rashtriya Krishi Vikas Yojna (RKVY), Department of Science and Technology (DST) and Department of Biotechnology (DBT) for funding support in the form of various R&D projects

Dr. Dhananjaya P. Singh

Principal Scientist (Biotechnology)

Email : Dhananjaya.Singh@icar.gov.in; dpsfarm@rediffmail.com

Dr. Renu

Principal Scientist (Agricultural Biotechnology)

Email : Renu1@icar.gov.in; renuiari@rediffmail.com

ICAR-National Bureau of Agriculturally Important Microorganisms,

(Indian Council of Agricultural Research, Ministry of Agriculture, Government of India)

Mau, 275101 Uttar Pradesh, INDIA

E-mail: Renu1@icar.gov.in; renuiari@rediffmail.com