Soil tillage and precision agriculture: A theoretical case study for soil erosion control in Brazilian sugar cane production

The variability of most soil properties is expressed at small scales. Agronomic practices and treatments are usually designed to be extremely uniform at this scale. The contradiction of applying uniform treatments to variable conditions is the key issue of precision agriculture. Traditionally, precision agriculture means variable application of material inputs such as fertilizers, pesticides and amendments. Although the practical results expressed in terms of economic feasibility or advantages for crop production are controversial, the basic concepts of precision agriculture applied to other inputs, such as time and labor, have theoretical advantages and may have a greater possibility to develop into profitable technology. This paper describes a theoretical example based on sugar cane production in a 77 ha watershed located in the southeastern part of Brazil. Precision agriculture concepts focusing on P-fertilizer inputs were compared with optimization of mechanical operations such as planting and harvesting. Measurable advantages for precision agriculture compared with traditional treatments were observed for mechanical operation efficiency but not for P-fertilizer. Recent practical experiences in Brazilian sugar cane production of treating soil conservation as spatially variable to gain efficiency in mechanical operations is a clear example of the economic feasibility of implementing precision agriculture by increasing efficiency instead of decreasing materials or increasing yields.