ABSORÇÃO DE NUTRIENTES PELA CULTURA DA CANA-DE-AÇÚCAR FERTIRRIGADA COM VINHAÇA EM UM LATOSSOLO VERMELHO

Abstract

Fertigation consists of soluble fertilizers application through the irrigation system, becoming a common practice in modern irrigated agriculture. This work aimed to evaluate the effects of different fertigation managements with vinasse on stalk yield, accumulation, export and return of macronutrients nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg) and sulfur (S) in sugarcane (var. RB86-7515), in the cane-plant cycle and in the 1st ratoon cycle, in a Cerrado Red Oxisol. The study was conducted under field conditions, in the farm Boa Sorte, municipality of Carmo do Rio Verde - GO, using the experimental design of randomized blocks with three replications. The evaluated factors consisted of two fertigation managements with vinasse (1x40 mm and 2x20 mm, in the cane-plant cycle and 1x40 mm and 1x20 mm, in the 1st ratoon cycle), six nutrients (N, P, K, Ca, Mg and S) of sugarcane aerial and root part, two plant parts (leaves and stalks) and five evaluation times in the plant-cane cycle (75, 160, 180, 250 and 300 DAP – days after planting) and four evaluation times in the 1st ratoon cane cycle (100, 170, 240 and 330 DAC – days after the 1st cut). In the cane-plant cycle, the fertigation management of 2x20 mm of vinasse promoted the accumulation of 769.42 kg ha-1 of K, the return of 176.03 kg ha-1 of K and the export of 593.39 kg ha-1 of K, higher values compared to the fertigation management of 1x40 mm of vinasse. In the first ratoon cycle, the fertigation management of 1x40 mm of vinasse promoted the accumulation of 650.73 kg ha-1 of K, the return of 159.17 kg ha-1 of K and the exportation of 491.57 kg ha-1 of K, higher values compared to fertigation management of 1x20 mm vinasse. Sugarcane leaves (var. RB86-7515) tend to accumulate a higher amount of N compared to stalks up to 160 DAP for the cane plant cycle and up to 100 DAC for the 1st ratoon cycle. This behavior is reversed after this period, making the stalk the part of the plant with the greatest N accumulation until harvest time. For sugarcane (var. RB86-7515), there was a stalk productivity of 93.4 and 114.0 t ha-1, in the plant cane cycle and in the 1st ratoon cane cycle, respectively.