In order to achieve more sound fertilizer recommendations, knowledge about nutritional requirements of rice in different growing systems is fundamental. The objective of this paper was to evaluate the effects of water levels on nutrition and nutrient exportation by upland rice (cultivar IAC 201) under two levels of mineral fertilizer. Experiments were conducted in the growing seasons of 1994/95 and 1995/96 on a Typic Haplustox, in Selvíria, State of Mato Grosso do Sul, Brazil. The experimental design was of randomized blocks, with four replications. The treatments were five water levels: natural rain and four water levels provided by sprinkler irrigation. Water level 2 (L2) was based on the crop coefficient (Kc) for upland rice. L1 and L3 were then defined as 0.5 and 1.5 times the Kcs used in L2, respectively. For water level 4 (L4), Kc = 1.95 was used during the entire plant cycle. The same treatments were applied in 1995/96 in a split-plot scheme. The subplots consisted in two NPK-fertilization levels (AD1 - 12 kg ha-1 of N, 90 of P2O5, and 30 of K2O; and AD2 - 24 kg ha-1 of N, 180 of P2O5, and 60 of K2O). Low water availability during the vegetative and reproductive phases decreased the dry matter yield, nutrient contents, and nutrient uptake. Sprinkler irrigation increased grain yield and nutrient exportation, independent of the water level. In soils with appropriate nutrient levels for the dryland system, the irrigated rice did not respond to increased mineral fertilization, despite the larger nutrient uptake.
Oryza sativa L.; sprinkler irrigation; macronutrient; nutrient exportation
