SOIL AND SOIL SOLUTION NUTRIENT CONTENT IN DRIP FERTIGATED CITRUS

Soil solution analysis has shown to be a promising method for soil fertility diagnosis, mainly in fertigation systems. The objective of this study was to evaluate the behavior of nutrients in soil and soil solution by supplying five doses of N, P2O5 and K2O (0, 25, 50, 100 and 200% of the recommended dose) via fertigation. The experiment was conducted during three seasons in Valencia sweet orange on Swingle rootstock. Soil and soil solution samples were collected after fertigation at each season. The supplied doses of N, P2O5 and K2O decreased pH in both soil and soil solution; however soil solution variation was 3.5 times higher. Such differences were also observed for P and K contents, which were 65 times and above 100 times higher than in soil, respectively. These nutrients had similar behavior in both environments with correlation values of 0.87 and 0.97 respectively, and both values of P and K increased according to fertilizer dose. The results suggested that soil solution analysis can be used as a tool to estimate values of pH, P, K, Mn and Zn in the soil, as well as to determine nitrogen availability in citrus production under fertigation systems.