Eficiência agronômica da adubação potássica na alface adubada com fontes alternativas de nutrientes

O objetivo desse estudo foi avaliar o efeito da aplicação de fontes alternativas de nutrientes na nutrição, produção e eficiência da adubação potássica na alface. O experimento foi conduzido em casa de vegetação, em vasos com 3,7 kg preenchidos com um Latossolo Vermelho Amarelo distrófico de textura média. O delineamento experimental foi inteiramente casualizado e os tratamentos foram distribuídos em arranjo fatorial 4 x 6, sendo quatro doses de potássio (0; 200; 400; 600 kg ha-1 de K2O) e seis fontes alternativas de nutrientes (brecha, ultramáfica, biotita xisto, flogopitito, subproduto de mineração e subproduto de chapada), com quatro repetições. Foram determinados o teor e o acúmulo de potássio (K), cobre (Cu), zinco (Zn) e níquel (Ni) na parte aérea da alface e com esses dados foram calculados dois índices de eficiência da adubação potássica. As aplicações de doses crescentes das fontes alternativas de nutrientes promoveram melhorias na nutrição e aumentos na produção da alface. A eficiência da adubação potássica diminuiu com o aumento nas doses de potássio aplicadas pelas fontes alternativas de nutrientes, sendo que o subproduto de mineração e a ultramáfica foram superiores às demais fontes. Diante disso, pode-se afirmar que as rochas silicáticas moídas e os subprodutos de mineração constituem uma opção para adubação em sistemas de produção orgânica e convencional.The aim of this study was to evaluate the effect of alternative sources of nutrients on the nutrition, yield and efficiency of potassium fertilization in lettuce. The experiment was carried out in a greenhouse, using 3.7 kg pots filled with a dystrophic red-yellow Latosol of medium texture. The experimental design was randomized, with treatments divided into a 4 x 6 factorial: four doses of potassium (0; 200; 400; 600 kg ha-1 K2O) and six alternative sources of nutrients (breccia, ultramafic, biotite schist, phlogopite, and mining and Chapada by-products), with four replications. Content and accumulation were determined for potassium (K), copper (Cu), zinc (Zn) and nickel (Ni) in the lettuce shoots, and from these data two indices were calculated for the efficiency of potassium as a fertilizer. The application of increasing values of alternative sources of nutrients promoted improvements in nutrition and increases in lettuce yield. The efficiency of potassium fertilization decreased with the increase in values of potassium taken from alternative nutrient sources, with the mining by-products and the ultramafic being superior to the other sources. Crushed silicate rocks and mining by-products can therefore both be used as fertilizer in organic and conventional production systems

PHOSPHITE AS PHOSPHORUS SOURCE TO GRAIN YIELD OF COMMON BEAN PLANTS GROWN IN SOILS UNDER LOW OR ADEQUATE PHOSPHATE AVAILABILITY

The effects of foliar and soil applied phosphite on grain yield in common bean (Phaseolus vulgaris L.) grown in a weathered soil under low and adequate phosphate availability were evaluated. In the first experiment, treatments were composed of a 2 x 7 + 2 factorial scheme, with 2 soil P levels supplied as phosphate (40 e 200 mg P dm(-3) soil), 7 soil P levels supplied as phosphite (0-100 mg P dm(-3) soil), and 2 additional treatments (without P supply in soil, and all P supplied as phosphite). In the second experiment, treatments were composed of a 2 x 3 x 2 factorial scheme, with 2 soil phosphate levels (40 e 200 mg P dm(-3) soil), combined with 3 nutrient sources applied via foliar sprays (potassium phosphite, potassium phosphate, and potassium chloride as a control), and 2 foliar application numbers (single and two application). Additional treatments showed that phosphite is not P source for common bean nutrition. Phosphite supply in soil increased the P content in shoot (at full physiological maturity stage) and grains, but at the same time considerably decreased grain yield, regardless of the soil phosphate availability. Foliar sprays of phosphite decreased grain yield in plants grown under low soil phosphate availability, but no effect was observed in plants grown under adequate soil phosphate availability. In general, foliar sprays of phosphate did not satisfactorily improve grain yield of the common bean plants grown under low soil phosphate availability.CNPq from BrazilCNPq from BrazilCAPES from BrazilCAPES from BrazilFAPEMIG from BrazilFAPEMIG from BrazilCNPqCNP

Margem de lucro proporcionada pela aplicação de um fertilizante NPK em diferentes níveis em cafeeiros irrigados

The lack of management preparation inherited down from past regulations interferes in economic results of production. During the productive cycles the quantity of fertilizers are effected without the technical recommendations, which may economically render the production. The product, therefore, demands information to act strategically on its own business. The main objective for this project was analyzed the profit margin provided by application of a fertilizer NPK at different levels in coffee plants irrigated. The analyses contemplated the harvests of 2012/2013 and 2013/2014 of an experiment carried out at the Federal University of Lavras (UFLA). The outlining was made in random blocks with six treatments and four repetitions, being six levels of fertilization with fertilizers containing N, P2O5 e K2O that were from 10, 40 ,70 ,100 ,130 and 160% of recommended standards for coffee producers of dry farming. There was a significant effect from the levels of fertilizers in effect in relation with the productivity on the biennium, and the maximum production was reached with the application of the fertilizer on the level of 145,57% of the recommended standard. The optimal economic production occurred with the application on the level of 118,12%. The economic maximum and optimal productions on the biennium generated a gross margin of R$18.205,73/ha and R$ 19.127,81/ha respectively, considering only the costs of fertilizers that was the variable factor.O despreparo gerencial herdado da antiga regulamentação do setor cafeeiro tem interferido nos resultados econômicos da produção. Ao longo dos ciclos produtivos as quantidades de fertilizantes são alteradas sem as devidas recomendações técnicas, podendo inviabilizar economicamente a produção. O produtor, portanto, demanda informações para agir estrategicamente sobre seu negócio. Objetivou-se com este trabalho, analisar a margem de lucro proporcionada pela aplicação de um fertilizante NPK em diferentes níveis em cafeeiros irrigados. As análises contemplaram as safras 2012/2013 e 2013/2014 de um experimento conduzido na Universidade Federal de Lavras. Seu delineamento foi em blocos ao acaso, com seis tratamentos e quatro repetições, sendo seis níveis de adubação com um fertilizante contendo N, P2O5 e K2O que foram de 10, 40, 70, 100, 130 e 160% da recomendação de adubação padrão para cafeeiros de sequeiro. Houve efeito significativo dos níveis de adubação sobre a produtividade no biênio, e a produção máxima foi alcançada com a aplicação do fertilizante no nível de 145,57% da recomendação padrão. A produção ótima econômica ocorreu com a aplicação no nível de 118,12%. As produções máxima e ótima econômica no biênio, geraram uma margem bruta de R$18.205,73 por hectare (ha) e R$ 19.127,81/ha respectivamente, considerando apenas os custos do fertilizante que foi o fator variável