Bio intensive Agronomy: A paradigm shift in agronomic research

Abstract

The term paradigm shift was first introduced by Thomas Kuhn in his highly influential landmark book, The Structure of Scientific Revolutions. Kuhns book shows how almost every significant breakthrough in scientific en- deavor is first break with tradition, with old ways of thinking, with old paradigms. The word paradigm comes from the Greek. It was originally a scientific term, and is more commonly used today to mean model, theory, perception, assumption, or frame of reference. In more general sense, its the way we see the world- not in terms of our visual sense of sight, but in terms of perceiving, understanding and interpreting. In pre green revolution period, the plant architecture of the cultivated cereal crops was long duration and tall. These plants were not responsive to input use i.e. with application of fertilizers and irrigation, they used to be lodged. Most of our agriculture was rainfed. Agronomic research therefore was revolving around increasing yield under this scenario available at that part of time. Simple fertilizer trial, tillage practices to conserve moisture and control weeds and mixed cropping were the main aspects of research. Farming was done for subsistence. Yields were sustained at low levels. Then, there was a breakthrough. Plant architecture was changed. Short duration dwarf varieties came into existence. Agronomic research also shifted from simple fertilizer trials to complex fertilizer experiments, mono- cropping to multiple cropping and scheduling irrigation. Use of herbicide increased to control weeds. With the expansion of irrigation, scheduling of irrigation became main focus and legumes went out of the cultivation and cereal- cereal cropping became predominant. Spread of rice- wheat cropping system in Indo-Gangetic Plain region is the glar- ing example of this. Due to this cereal-based crop rotation, natural resources started degrading and weeds de- veloped resistance to herbicides. Factor productivity started declining. Presently these are our cultivation prac- tices i.e. our convention, which is chemical based and input intensive, this we wish to change to bring bio-in- tensive agronomic practices, which will include massive use of biomanures, biofertilizers and biopesticides. The research on rhizospheric engineering and carbon sequestration has to be strengthened to improve the soil health and nutrient use efficiencies. Rhizospheric engineering refers to bringing changes in root architecture by modifying planting methods and crop geometry and also improving root zone soil profile through rhizodeposition. In irrigated ecosystem, where legumes could not be introduced due to their sensitivity to water, sugarcane is to be brought in the system, because several beneficial microorganisms are associated with its roots, which mobilizes soil materials. Also, large quantity of root mass of sugarcane upon decomposition adds substantial quantity of organic matter to the soil.