Formas de fósforo e potássio em solos cultivados com Meloeiro Fertirrigado.

Abstract

The cultivation melon in regions with young and poorly weathered soils, as in most the soils the Northeastern Semi-arid, has compromised fruit production and quality. In this sense, studies involving nutritional dynamics in the soil are relevant to maximize the yield the melon crop in the Northeast, in order to evaluate the potassium and phosphorus forms present in soils under the fertirrigated melon cultivation in the State Rio Grande the North and Ceará. Soil samples were obtained from two experiments on the nutrient absorption gait melon, the first one located in the municipality Governador Dix-Sept Rosado, Açú-Apodi (RN) microregion and the second one in the Municipality of Aracati (CE). Two soils were studied, in the first one the treatments comprised a factorial arrangement 7 x 2, being two layers soil (0-20cm and 20-40cm) and seven times collection, with four replications, totaling 56 experimental units. In the second experiment the treatments included a 9 x 2 factorial arrangement, two soil layers (0-20cm and 20-40cm) and nine collection times, with four replications, totaling 72 experimental units. Initially the chemical and physical characterization the studied soils was carried out. Phosphorus (P-available, P-soluble, P-total and P-total) and Potassium (K-available, K-soluble, K-non-exchangeable) in the soil were analyzed. The soluble fractions of P were higher in the Quartzipsamments while the organic P was superior in the Haptic Vertisol. However, total P contents were similar between soils. In general, the superficial layer (0 to 20 cm) had the highest available levels P. However, in the Neosolus, at the end the cycle the melon, there was a higher concentration this nutrient in the layer of 20 to 40 cm. In both soils , in general, the contents all fractions of K were higher in the superficial layer (0 to 20cm). The Vertissolo presented higher availability and higher stocks K. In the Neosol there was an apparent leaching of K at the end the cycle the melon, increasing the exchangeable contents in the layer of 20 to 40 cm. In both soils, there was a significant relation between the capacity factor of P with the accumulated amounts of nutrient by the plant. However for K, only in the Neosol there was a positive relation between the capacity factor, the applied doses K with and the amount nutrient extracted by the plant.