Efficacy of biological soil amendments and biocontrol agents for sustainable rice and maize production

Abstract

Exploiting the agroecosystem services of soil microbes appears as a promising effective approach to alleviate the negative impacts on soil systems and crop production. Lack of soil organic matter (SOM) is a prevalent feature of degraded soils. Different biological soil amendments, such as organic manure, compost, vermicompost, indigenous microbes, and crop residues, are widely used in reclamation of degraded soils. The biological soil amendments also furnish a valuable source of fertilizer for growing rice and maize and also boost physicochemical and biological parameters of soil such as water holding capacity, moisture content, electrical conductivity, organic carbon content, and population of beneficial microbes which directly correlates to soil health and fertility. However, efficiency of amendments applied based on variety of factors including the composition and characteristics, soil microflora, and environmental conditions can accelerate initial reclamation and lead to self-sustaining primary productivity of crops. On the other hand, high cost of chemical fertilizers, pesticides, and other agricultural inputs and their harmful environmental legacy have encouraged researchers to explore the use of microbial-mediated amendments to play a central role in raising productivity and inhibition/suppression of pathogenic population below levels at which they cause economic and other effects to the crops as well as the environment. Biological control can be achieved through one or more mechanisms, viz., antibiosis, competition for nutrients and/space, induced resistance, plant growth promotion, and rhizosphere colonization ability. Potent biocontrol agents such as Bacillus sp., Pseudomonas sp., and Tricoderma sp. prove to be very promising in controlling soilborne diseases of rice and maize crops employing both antibiosis and induction of host resistance. Determination of the modes of action of biocontrol agents is obligatory to provide higher level of protection to crop under a particular environmental condition that exists in divergent agroecosystems. This chapter reviews an insight of mechanisms of biological soil amendments and biocontrol agents and their emphasis on soil amelioration with the goal of a sustainable agricultural system.