Atributos do solo, qualidade do lixiviado e crescimento de plantas de milho sob aplicação de água residuária da mandioca

Abstract

Cassava wastewater, wastewater from cassava (Manihot esculenta Crantz) processing industrial, is produced in volume large. When low-cost solutions are not viable, usually dumped in rivers or in the soil, provide environmental impact. The cassava wastewater fertilizer has potential because great its nutrients composition of especially potassium, but when used indiscriminately provokes of basic cations imbalance in soil. To evaluate the potential of cassava wastewater, two study were developed. The study first aimed to evaluate soil characteristics and leachate quality as function of cassava wastewater rates applied to columns containig soils of different textures. PVC columns (15 x 80 cm) were used to simulate a 60 cm soil profile. The soils studied were: Cohesive Yellow latosol, Carbonatic Haplic Vertisol and Orthic Quartzarenic Neosol. Aiming to supply the K requirement to maize, 4.7 m³ ha-1 of cassava wastewater was applied to the Vertisol and Latosol white the Neosolreceived 9.6 m3 -1ha. The Wastewater promoted increase on the K contents for the 0-20 cm layer of soil. The results showed that the cassava wastewater dose applied is safe regarding salinization and changes in floculation. In the second aimed to evaluate the potential of cassava wastewater as a potassium fertilizer to maize and the alteraions it provokes in soil chemical characteristic. Two soils (Carbonatic Haplic Vertisol and Orthic Quartzarenic Neosol) were put in 3 kg pots. These soils received wastewater doses equivalent to 0, 1, 2, 3, 4 and 5 times the amount of K recommended to maize. This was equivalent to 0, 4.7, 9.4, 14.1, 18.8, 23.6 m3-1 ha for the Vertisol and 0, 9.6, 19.2, 28.8, 38.5, 48.1 m3-1 ha the Neosol. The results showed that the application of cassava wastewater improved soil chemical characteristics, but it did not change soil pH. Cassava wastewater along with mineral mineral fertilizers poses potencial. On the other hand, wastewater alone was not able to provide the K requeriment to plant.