Abstract
To diagnose and monitor the nutritional status of commercial crops, reference standards must be established based on chemical analyses of soils and leaf tissues. Therefore, the objective of this study was to establish sufficiency ranges, DRIS standards and leaf nutritional diagnoses for palisade grass pastures in the rainy and dry seasons. Of a total of 105 sampled pastures, the 20 highest-yielding areas were used to establish reference standards. In the other, low-productivity pastures, the nutritional status was diagnosed in both the rainy and dry seasons for nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), sulfur (S), boron (B), copper (Cu), iron (Fe), nickel (Ni), molybdenum (Mo), and zinc (Zn). A productivity of 15 tons ha-1 year-1 was determined as the threshold to separate high-yielding (> 15 tons ha-1 year-1) pastures from low-productivity pastures (< 15 tons ha-1 year-1). Sufficiency ranges and foliar DRIS standards were established for palisade grass pastures in the rainy and dry seasons, which resulted in the recommendation of region- and season-specific sufficiency ranges and DRIS leaf standards. In the rainy season, in more than 50% of the evaluated pastures, nutritional deficiencies in all nutrients except K, B and Zn were observed, while in the dry season, only N, P, Cu, and Mn were deficient.
Highlights
The agriculture industry, which accounts for approximately 21% of the Brazilian gross domestic product, represents a source of wealth for the country and generates thousands of jobs
The same trend was not observed in the dry season, as only N, P, Cu, and Mn were below the recommended ranges (Table 2) in more than half of the evaluated pastures (Table 3)
DRIS standards and sufficiency ranges were established for highly productive U. brizantha pastures in the rainy and dry seasons
Summary
The agriculture industry, which accounts for approximately 21% of the Brazilian gross domestic product, represents a source of wealth for the country and generates thousands of jobs. Livestock accounts for 30% of this sector (ABIEC, 2016), and 167 million hectares of pasture are used for livestock production (EMBRAPA, 2018). In Brazil, the area of pastures cultivated with species of the genus Urochloa has increased significantly in comparison to that cultivated with other forages. Due to its easy adaptation to moderately fertile soils, the species U. brizantha, commonly called palisade grass, is one of the most widely planted and is cultivated in a large part of the pastures in Brazil (Montagner, 2016). According to Townsend, Costa, and Pereira (2010), pasture degradation caused by improper management is an evolutionary process of loss of forage vigor and yield that, due to the impossibility of natural recovery under grazing, affects animal production and performance and culminates in the degradation of soil and natural resources
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