Paulo Sergio Pavinato

Silage of white oat under nitrogen fertilization and pre-wilting

The forage conservation as silage is a way to provide good quality forage during grazing scarcity periods, in this way, the objective was to evaluate the effect of pre-wilting and nitrogen fertilization on the fermentation characteristics and nutritive value of white oat silage, in two harvest stages. The experiment was conducted in 2011 at UTFPR, Dois Vizinhos-PR, Brazil. The experimental design was in a randomized blocks with two factorial arrangement and three replicates. The main treatments were six nitrogen doses: 0, 40, 80, 120, 160 and 200 kg ha-1, and secondary the stages of cutting for silage: early flowering with and without pre-wilting, and at blooming without pre-wilting. It was observed that nitrogen fertilization promoted a reduction in pH and mineral content of the silage, reducing fiber content and increasing crude protein content (CP), when made at oat early flowering. The effect of prewilting in early flowering inhibits the production of effluents and has higher levels of CP, without any effect on the fermentation and nutritional value. The silage at blooming stage features better standards of fermentation, with lower pH and buffering capacity, but with lower nutritional value.

Additives incorporated into urea to reduce nitrogen losses after application to the soil

The objective of this work was to develop urea-based fertilizers with internal incorporation of urease inhibitors and other additives in the granule. The effects of the incorporation of NBPT, copper (Cu+2), boric acid (H3BO3), elemental sulphur (So), and a clay mineral from the zeolite group in powder urea – with ten different combinations of these additives – were evaluated as to N losses by volatilization and leaching. The losses in laboratory-developed formulations were compared with those of commercial fertilizers coated with the same additives (Super N, FH Nitro Mais, and FH Nitro Gold). The evaluations were made in greenhouse conditions, using a Ultisol accommodated in PVC columns. Nitrate and ammonium leaching was evaluated in the solution percolated through the soil columns. Ammonia volatilization was measured with a semi-open static chamber. The incorporation of urease inhibitors (NBPT, H3BO3, and Cu+2) into the urea granules was efficient to reduce N volatilization. Ammonia volatilization in the laboratory-developed ureas was lower than in commercial fertilizers coated with the same additives, while ammonium sulfate losses by leaching were similar. The addition of zeolite does not reduce N volatilization. Mineral N leaching in the soil profile is not affected by urease inhibitors.

Nitrogen Efficiency and Nutrient Absorption by a Sorghum-Oats Forage Succession

Balance between nutrient uptake by the crop and the amount of applied fertilizer is desired in a production system, and this measurement can predict the nutrient use efficiency. The present study aimed to evaluate nitrogen- (N-) use and recovery efficiency and extraction of N, phosphorus (P), and potassium (K) by sorghum (Sorghum bicolor) and black oat (Avena strigosa) forages under nitrogen fertilization in three consecutive crop cultivation. The experiment was carried out at Federal Technological University of Parana (UTFPR), Dois Vizinhos, Parana, Brazil, in Rhodic Hapludox soil. Treatments included 0, 37.5, 75, 150, 225, 300, and 375 kg N ha−1 applied to sorghum in the summer seasons of 2010/2011 and 2011/2012, intercalated by, respectively, 0, 40, 80, 120, 160, 200, and 240 kg N ha−1 applied to black oat in the winter/2011. Forage production, N, P, and K extraction, and N recovery efficiency were determined through samplings during the crop cycle. The highest sorghum forage production and N and K extraction were under 230 to 300 kg N ha−1, which was around 190 kg N ha−1 for black oat. The values of N recovery, efficiency, and N-use physiological efficiency were higher under lower N rates for both crops. Based on this, about 150 kg N ha−1 is recommended to obtain good sorghum forage production with higher N efficiency levels, which is about 120 kg N ha−1 for black oat.