Treatise on Conservationist Agriculture (Paperback)
According to the scientific community, conventional agriculture causes environmental damage as a result of the intensive use of agrochemicals and intensive agricultural mechanization. Conventional production management tends to exhaust natural resources, with biological, physical and chemical degradation of soils. Altmann (2010) argues that the low mobility of phosphorus in the soil profile makes it possible to make fertilization in the best return crop, using the residual for the substitute crops, without significant losses. The researcher also found that the response of cotton in soil with high P content was not significant from 80 kg ha-1 P2O5, which in other trials has been up to 120 kg ha-1 P2O5. There was a tendency of response of corn and soybean up to 107 kg ha-1 of P2O5 applied in the 3 years of the cotton-soybean-corn system.For potassium fertilization in soybean / corn or soybean / rotation systems, the literature suggests the displacement of part of soybean fertilization for cereal cultivation. Because cereals are more responsive, residual potassium can be partially or wholly used by soy in the next cycle. However, it is important to adopt conservationist practices to avoid nutrient losses in the off-season (BENITES et al., 2010).Research results obtained by Altmann (2010) established that potassium fertilization did not promote significant yield increases from 80 and 160 kg ha-1 K2O, respectively for corn and cotton, and above 240 kg ha-1 K2O., considering the potassium fertilization in the three years of the cotton-soybean-corn production system. For soybeans, the best yields were obtained with the application of 53 kg ha-1 of K2O, not differing from the treatment in which 120 kg ha-1 of K2O was used in cotton and soya without fertilizer (ALTMANN, 2010).Both cotton, soybean and corn had their productivity significantly affected by the lack of fertilization in the three years of the trial, reaching a 54.7% reduction in soybean production in the treatment without fertilizer, indicating that in sandy soil there is need to use a starter fertilizer to avoid harming the potential of crops (ALTMANN, 2010).Cotton is the crop whose crop remains has the highest N-P-K credit, a fact that enables differentiated management of the next crop fertilizer. Another relevant aspect is that the required proportion of nutrients changes over time, being more flexible for phosphorus and more sensitive for nitrogen and potassium. In many properties there has been a negative nitrogen balance in the system, which is becoming the limiting factor for high productivity.