Crescimento e produção de cana-de-açúcar em diferentes fontes de fósforo

Abstract

The phosphorus supplied to the cultures is present in fertilizers under different chemical forms and presents different behaviors in the soil, exerting influence in the growth and development of the plants. To evaluate the influence of phosphorus sources and the reduction of the total dosage of this nutrient to the growth and production of sugar cane was carried out a field experiment in Coruripe Alagoas, with 10 fertilizers treatments: T1 (control), T2 (NK), T3 (super simple phosphate), T4 (super triple phosphate), T5 (Fosmag), T6 (Foscana), T7 (MAP), T8 (NPK 06-26-24), T9 (Compost sugar cane filtrate, sugar cane residue and ash) e T10 (super simple phosphate - parceled). The experiment was design in random blocks with four replicates and it was used the sugar cane variety RB75126. The following biometrics indexes had been used for growth estimation: shoots number, height of plants, diameter of culms, leaf area, leaf area index, biomass of the aerial part, rate of culms growth, rate of biomass production of the culms and relative rate growth. After four and eight months, were collected leaf samples for P analysis. After eight months, were collected soil samples to evaluate the P available. The field and industrial production was evaluated after twelve months. The P sources showed to influence the height of plants after ten months, the leaf biomass after two months, the leaf contents after four months and the final productivity. The major growth rate of the culms and their fresh matter production occurred between 120 and 180 days after the plantation, just when they presented the biggest leaf area index and water availability. The available P levels in the soil were in a adequate amount to provide an yield highter 80 t ha-1. The compost added proved to be sufficient to supply the total amount of P required by the sugar cane in the soil. The reduction in the total P dosage did not jeopardize both the development and the yield of the sugar cane. The super triple phosphate was superior to super simple phosphate, Fosmag and NPK to improve the field and industrial income. It also presented higher levels of P in the leaves as compared to the compost. All sources of P used in this work were appropriate to supply the sugar cane RB75126 requirements. Therefore, the price, the availability of the P source and ease of its application should also be considered.