Resumo

ROMERO, Juan I. et al. Requerimiento y extracción de nutrientes de una variedad de caña de azúcar bajo riego por goteo y en secano en Tucumán-Argentina. Rev. ind. agric. Tucumán [online]. 2020, vol.97, n.1, pp.9-16. ISSN 1851-3018.

Continuous agricultural use without a fertilization strategy to replace nutrient removal, leads to soils impoverishment and nutritional imbalance and the loss of their productive capacity. The objective of this study was to determine nutrient requirement and removal under rainfed and irrigated conditions for the most planted sugarcane cultivar in Tucumán, in order to contribute to a more sustainable crop nutrition management. The treatments were: rainfed and drip irrigated, in a completely randomized design with five replications, during 1st to 4th ratoon. Crops were fertilized according to local recommendations (90 kg N ha-1 year-1 and 20 kg P2O5 ha-1year-1, according to soil analysis). At each harvest, yield components were determined and aerial biomass samples were used to determine the amounts of N, P, K, Ca and Mg present in each organ. From these data, nutrient requirement and removal were determined. Irrigated and rainfed average yields were 109.9 and 78.3 t ha-1 and its aerial biomass 43.6 and 31.7 t ha-1, respectively. Drip irrigated treatment presented greater nutrient requirement and removal per unit area. Requirement (kg ha-1) increased by 23% to 44%, and removal (kg ha-1) increased from 26% to 72%, varying by nutrient. In tops and leaves, harvest residues, 32% to 73% of total N, P, K, Ca and Mg were determined (average from irrigated and rainfed). This study quantifies system nutrient output, and its increase associated to greater yields in irrigated sugarcane crops. It also highlights the importance of harvest residues (green harvest) on nutrient cycling and sugarcane agroecosystem sustainability. 

Palavras-chave : sustainability; nutrient balance; drip irrigation.

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