Assessment of the nutritional status of grassland: nitrogen nutrition index

Abstract

The aim of this study was to assess the Nitrogen Nutrition Index (NNI) of an Urochloa plantaginea pasture submitted to different nitrogen (N) levels and forage mass (FM) through dilution curve model. The experimental design was a random block with six treatments in a factorial scheme. The treatments combination consisted of three nitrogen levels (0, 200 and 400 kg ha-1 of N) and two forage mass (low mass at 2,000 kg ha-1 of DM and high mass at 3,600 kg ha-1 of DM) in a continuous stocking rate grazing method. Urochloa plantaginea forage production was higher at the nitrogen intermediate level (200 kg ha-1 of N), being 31% superior than treatment without nitrogen, which showed unsatisfactory nitrogen nutritional index and due to it, limited forage growth. This fact was not observed at the 400 kg ha-1 of N, where nitrogen luxury consumption occurred showed by the satisfactory levels of this nutrient in the plant tissue. Nitrogen dilution curve allows the diagnosis of the plants nutritional status.

Keywords

• Dilution curve; Fertility; Forage production; Nutritive value; Urochloa plantaginea