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Em função do aumento das áreas agricultáveis e pela busca por uma agricultura mais sustentável, tem levado a busca de novas soluções que visem melhorar os níveis de produtividade. Partindo da hipótese de que o uso do extrato de alga vermelha Kappaphycus alvarezii aplicado via foliar pode estimular um melhor desenvolvimento vegetativo e reprodutivo da soja, o presente trabalho teve como objetivo avaliar o comportamento morfológico da cultura da soja submetida a aplicação de diferentes doses (0,0; 0,5; 1,0; 1,5 e 2,0 L ha-1) do extrato de algas vermelha (Kappaphycus alvarezii). Foram mensuradas as variáveis morfológicas (diâmetro de caule, número de nós, altura de planta, área foliar, número de vagens e número de grãos), variáveis fisiológicas (índice Falker® de clorofila), massa de 1000 grãos e produtividade de grãos. Os dados foram submetidos a análise de variância (p

To achieve high corn yield, optimal amounts of nutrients that can be extracted by the crop must be supplied at adequate proportions. Vinasse from sugarcane ethanol production can be applied as a soil fertilizer to corn crops in ethanol production plants. In this context, the present study compared the effects of mineral potassium fertilization with potassium chloride and organic fertilization with concentrated sugarcane vinasse on corn dry matter and grain yield and explored the technical and economic efficiency of these sources. The experiment was carried out at the experimental station of the Federal Institute Goiano, Rio Verde Campus, Brazil. The experiment followed a randomized block design in a 2 × 4 factorial scheme, with three replicates. The treatments comprised two sources of potassium, namely concentrated vinasse and potassium chloride, applied at four doses of potassium, representing 0%, 50%, 100%, and 200% of the recommended rate for corn. The dry matter accumulation of corn throughout the crop cycle, yield components at harvest, and technical and economic efficiency of the applied potassium sources were measured. Neither potassium dose nor its source affected leaf, stem, and aboveground dry matter accumulation at harvest. Regardless of the potassium source, the 100% dose produced higher cob dry mass, grain dry mass, grain dry mass per ear, grain yield, number of bags of 60 kg ha−1 produced per hectare, and harvest index. The agronomic efficiency of vinasse compared to potassium chloride was 68.5% at the 100% dose of the recommendation, showing enough potential as an organic fertilizer in corn crop.

Sugarcane is the most promising among renewable biofuel-producing crops. An adequate availability of water and nutrients, especially nitrogen (N), is of utmost importance. From the hypothesis that the source and the rate of N fertilization influence the N use efficiency of an irrigated soil–sugarcane system, this study aimed to evaluate the stalk and crop residues (pointer and leaves) yield, as well as the N utilization, from different rates of ammonium nitrate and urea by irrigated sugarcane in the cane plant cycle, using an 15N isotopic dilution technique. The soil used for the experiment was an Oxisol (Rhodic Haplustox) Cerrado (savannah) phase. The experiment was carried out at a farm of the Raízen Mill, which was located in the municipality of Jataí, Goias State, Brazil. The sugarcane variety IACSP95–5000 was used in a randomized block design, with three replicates, four N rates (30, 60, 120, and 180 kg ha−1), and two fertilizer sources labeled with 15N isotopes (urea and ammonium nitrate). The average value for N utilization was 60.17% for the ammonium nitrate source and 44.95% for urea. The responses in the percentage and quantity of N in the sugarcane from the fertilizer increase with the increasing N rate. The soil was the main N source for sugarcane. The higher stalk and pointer yield was recorded at the average rate of 143.61 kg N ha−1. Further studies are needed to evaluate the residual effect of N in the next cycles.