Resposta da batata cv. Cupido à fertilização organomineral

Potato crop cycle is relatively short and presents high yield per area; therefore, it is a very demanding culture for available nutrients in the soil solution. Despite its importance and the large number of studies about the crop, there is little research on plant nutrition regarding the use of organomineral fertilizer. This study evaluated potato, cv. Cupid, development and productivity as a function of fertilization with pelletized organomineral fertilizer. The experiment was done in Perdizes, Minas Gerais, in the rainy season of 2014/2015. The experimental design was a randomized blocks, with factorial arrangement of 4 x 2 (doses x management) and a control with mineral fertilizer, with 3 repetitions. Organomineral fertilizer doses were 25, 50, 75 and 100% of the conventional mineral dose, which was 600 kg ha-1 K2SO4, 850 kg ha-1 NH4H2PO4, and 300 kg ha-1 (NH4)2SO4 of topdressing 19 days after planting (DAP). Fertilization managements were with or without topdressing at 19 DAP, when the potato was hilled. Two plants per plot were sampled at 36, 50, 64 and 81 DAP and analyzed for leaf, stem and dry matter contents. DRIS - Diagnosis and Recommendation Integrated System was applied at 36 DAP and the potatoes were harvested 112 DAP and subjected to tuber classification. Throughout the cycle, stem, leaf and tuber dry mass showed no significant differences between the fertilization managements. The doses of organomineral fertilizer and topdressing management does not affect productivity, and the lower doses (25%) were similar the greater ones and the control, with an average of 16.8 t ha-1, demonstrating that it is viable to make a single application of organomineral fertilizer at planting due to operational efficiency. The low yields observed were due to high rainfall and temperature, creating favorable conditions for the incidence of pests and diseases. According to DRIS, the organomineral dose 75% for topdressing, presented the best nutritional balance.

Desempenho agronômico do milho com diferentes fontes e doses de nitrogênio

Nitrogen (N) is one of the major nutrients nutrients absorbed in corn crops, for this reason, nitrogen based fertilizers are expensive and suffer large losses to the environment. Therefore, a diversity of fertilizers, known as special or of enhanced efficiency fertilizers, has been commercialized. The aim of this study was to evaluate the effect of different sources and levels of nitrogen fertilization in coverage, for agronomic characteristics and corn grain productivity, cultivated in the Cerrado region. The experiment was installed in 2015, in Monte Carmelo-MG. The experimental design utilized was a RCBD with four replications. The treatments consisted of five N sources (common urea, polymerized urea, urea combined with NBPT (thiophosphate N-n-butiltriamida or N-n-butiltriamida of thiophosphoric acid), organomineral combined or not with NBPT), five topdress N levels (40, 80, 120, 160 and 200 kg ha-1) and a control (no N topdressing). The evaluated parameters were: the first spike insertion height (FSIH), plant height (PH), stem diameter (DC), number of rows per spike (RS), number of grains per row (GR), spike length (SL), spike diameter (SD), prolificacy (EP), 1,000-grain weight (TGW), leaf chlorophyll index (LCI), content of foliar nutrients, dry matter in aerial part of the plant (DM) and productivity (PG). The results showed that, with the exception of stem diameter, there was no significant statistical difference between sources of nitrogen, indicating that the organomineral source is as efficient as a mineral source. Regardless of the source, the addition of N fertilizers in increasing doses promoted enhanced development of corn plants, increased chlorophyll content, stem diameter, leaf N content, crude protein and productivity. For most phytotechnical features, there was no significant statistic difference in treatments compared to control.