One of the principal techniques in modern rice culture is soil puddling. This method enables the planting of as many as three crops per year instead of a single annual harvest. It has, however, the effect of excluding the traditional practice of crop rotation whereby soil was naturally refurbished with nitrogen and other organic nutrients from other plants. Synthetic fertilizers, especially nitrogen, phosphorus and potassium, have to be applied in increasingly bigger doses to offset the rapidly deteriorating condition of the soil. Repeated agrochemical applications in turn lead to the disappearance of another important natural source of nutrients, the nitrogen-fixing algae in the soil.
Over 1,000 species of predators and parasites have been identified in the traditional rice culture, including nitrogen-fixing algae, humus building agents, and natural enemies of rice-attacking pests. Repeated use of fertilizers, insecticides, molluscicides, herbicides and rodenticides has indiscriminately decimated the number and type of rice paddy inhabitants. The introduction of heavy machinery compacts the soil in paddies as well as neighbouring fields, increasing soil runoff, hence erosion and agrochemical pollution, and hampering soil aeration, root growth and penetration. The disappearance of nutrient-manufacturing algae and vegetation deprive rice plants of naturally fertile ground, while the loss or contamination of water reptiles, fish, frogs and snails deprives people of an important food source. Organochloride insecticides were found in about half of farmers' blood samples.