Nutrient Content and Partitioning Patterns in Sugarcane Ratoon.

Plant nutrient ratios can be employed as a valuable tool for determining nutrient imbalances for sugarcane ratoon in green cane management system. The main goal of this study is to investigate dry matter and nutrient (nitrogen–N, phosphorous–P, and potassium–K) content and partitioning in sugarcane ratoon at varying stalk yield (diverse environments, soil-weather). Three sites were established on two tropical acid soils (two in a Eutrustox and one in a Hapludox), State of São Paulo, Brazil. Seasonal biomass and nutrient (N, P, and K) uptake patterns were summarized from four sampling times collected throughout sugarcane ratoon season. At all sites, nutrient partitioning (in diverse plant fractions), internal efficiencies (yield to nutrient uptake ratio), and ratios (N:P and N:K) were determined. During the period of ratoon growth, sugarcane exhibited three distinct phases: first phase – lag phase or slow growth; second phase – lineal growth; and the last phase – declining growth (maturation). In general, for produce one Megagram (Mg) of stalks is required 1.45 kg of N, 0.24 kg of P, and 2.70 kg of K. For the nutrient partitioning process, dry leaves (senesced leaves) portrayed lower nutrient content (N, P and K) when compared with tops (functional leaves). Greater stalks yield and narrowed N:P ratio (6:1) were documented for tops of sugarcane when increasing nutrient content for N and P together. High-yielding sugarcane systems were related to superior nutrient content with a more balanced N:P (6:1) and N:K (0.5:1) ratios. Further research is needed for integrating the nutrient balance concept in decision nutrient management support tools for assisting sugarcane producers on the farming decision-making process.