Produtividade do capim Paiaguás submetido a doses de nitrogênio

Abstract

Pastures are the main source of feed for ruminants due to their low cost and nutritional qualities, but the lack of adequate maintenance and replacement of nutrients over the years causes a degradation process, reducing nutritional value and pasture support capacity. Nitrogen is the nutrient required in larger amounts by pasture and is directly linked to productivity of green mass per hectare as well as to protein content. The percentage of nutrients in forage leaves can aid in the analysis of visual symptoms, whether it is deficiency, toxicities, fertilization recommendations and also monitor the nutritional status of the plant. Therefore, we have used tools that help this diagnosis without the destruction of plants, such as the use of digital image and chlorophyll meter, obtaining satisfactory results in several cultures. The new cultivars of forage plants launched in the last years have been the focus of studies in the search to improve the knowledge about the dynamics of growth and productivities as well as the responses to nitrogen fertilization. Among the cultivars launched, the one that stands out is Uroclhoa brizantha cv. BRS paiaguás. This forage has as main characteristics a high vigor, ease of management and good nutritional value with an important differential that is the productivity in the dry season with good adaptation to soils of average fertility. The objective of this work was to evaluate the effect of nitrogen fertilization on the productive and chemical characteristics of U. brizantha cv. Paiguás, evaluating the efficiency of the digital image and the chlorophyll meter to obtain green color indices. The experimental design was a randomized block with five treatments and four replications. The treatments were composed of doses of N (0, 75, 150, 300 and 600 kg ha-1). The maximum productions obtained were 21.225 and 13.710 kg ha-1 year-1of DM for the first and second cycle, respectively. However, it was observed that both the chlorophyll meter and the digital image were effective to recommend the nutritional status of the plant in N. The paiaguás grass responds to the N in a similar way to the other Uroclhoas brizantha.