The objective of this study was to evaluate the effect of doses and frequency of application of potassium fertilizer on the alfalfa dry matter yield and potassium content in plant and soil. The experimental was carried out in a Typic Hapludox and was designed in randomized blocks in 4 X 4 factorial with 3 replications. The treatments were 4 levels of potassium in topdressing fertilization (0, 600, 1200 and 1800 kg ha-1 year-1 of K2O) and 4 frequency of application (12 = after each cutting, 6 = after two cuttings, 4 = after three cuttings; and 2 = two applications per year). The use of 1420 kg.ha-1 per year of K2O applied after two cuttings (6 applications per year) increased alfalfa dry matter yield until 30500 kg ha-1 and provided the best use of K at the higher doses of fertilizer. Alfalfa shoot total K removal reached 704 kg ha-1 per year of K2O with the application of 1623 kg ha-1 per year of K2O. At the end of the experiment, soil exchangeable K increased with K rates, and the differences were observed util 0.6 m of depth.

The zeolite and urea mixture may be use to improve N efficiency use of silage corn. The objective of this study was to evaluate dry matter yield, quality components and nutritional levels of nitrogen of silage corn fertilized with urea and zeolite mixture. The experimental design was a 2 X 4 X 4 factorial randomized block design with three replications. Treatments comprised two types of stilbite zeolite (natural and concentrated), four levels of nitrogen (0, 50, 100 and 200 kg.ha-1) and four ratios of zeolite (25%, 50% and 100% of N level). Treatments were applied 60 days after planting with the topdressing fertilization. The ratio of 62% and 48%, respectively, of concentrated (650 g kg-1 of stilbite) and natural (470 g kg-1 of stilbite) zeolite with urea increased silage corn dry matter production and provided the best use of N at the higher doses of fertilizer, as indicated by higher levels of N in leaves. There were no significant differences between levels of fertilization and quality compounds: neutral detergent fiber, acid detergent fiber and in vitro digestibility. But crude protein increased linearly with N levels.

The zeolite and urea mixture may be use to improve N efficiency use of silage corn. The objective of this study was to evaluate dry matter yield, quality components and nutritional levels of nitrogen of silage corn fertilized with urea and zeolite mixture. The experimental design was a 2 X 4 X 4 factorial randomized block design with three replications. Treatments comprised two types of stilbite zeolite (natural and concentrated), four levels of nitrogen (0, 50, 100 and 200 kg.ha-1) and four ratios of zeolite (25%, 50% and 100% of N level). Treatments were applied 60 days after planting with the topdressing fertilization. The use of concentrated (650 g kg-1 of stilbite) or natural (470 g kg-1 of stilbite) zeolite with urea increased silage corn dry matter production and N leaf concentrations.