Productivity and establishment of DRIS indices for tubers of the potato cultivar 'Agata'

In crops that are very demanding of nutrition, such as the potato, it is important to know the dynamics between nutrients, thereby ensuring high yields. In this context, the objective of this work was to evaluate tuber yield in the potato cultivar 'Agata' when subjected to different levels of fertilisation, and by means of the productivity and leaf analysis, to establish indices for the Diagnosis and Recommendation Integrated System (DRIS). Three experiments were carried out [nitrogen (N), phosphorus (P) and potassium (K)] in Sao Gotardo and Itajuba in the state of Minas Gerais, Brazil. The dosages tested were 0, 70, 140, 210 and 240 kg N ha(-1), 0, 150, 300, 450 and 600 kg K2O ha(-1) and 0, 200, 400, 600 and 800 kg P2O5 ha(-1). At 30 days after planting (DAP), leaves from each plot were sampled for analysis. At the end of the experiments the tubers were harvested and the productivity of the useable area of the plots was calculated. DRIS allows the sequence of nutrient limitations in potato crops to be known, allowing adjustment of the ratios between nutrients throughout the crop cycles in the area and optimising the management of fertilisation. Rates of 0 to 450 kg K2O combined with 140 kg N and 400 kg P2O5 reflected in higher yields due to the better dynamics between the nutrients in the soil solution, and consequently better absorption and development. However, the results should be evaluated bearing in mind the reality of the location, because the balance between nutrients also depends on the type of soil, the cultivar, the climatic conditions and the level of technology of the producer.