Marcos Vinicius Mansano Sarto

Produtividade de milho cultivado em sucessão à adubação verde

The use of previous crops which have the capacity of supplying nitrogen to maize by symbiotic fixation or nutrient recycling is important to yield maintenance. This study aimed at evaluating the yield of maize grown in succession to green fertilization . A completely randomized blocks design was used with four replications and the following treatments: maize grown on black oat, black oat + oilseed radish, black oat + white lupin, white lupin, crambe, spontaneous vegetation (fallow ground) and spontaneous vegetation (fallow ground) + topdressing nitrogen fertilization. Concerning grain yield, significant differences were observed among treatments. The maize grown on black oat + white lupin straw reached the highest yield (10,817 kg ha -1 ), resulting in a higher income and differing from the one grown on black oat and crambe straw and spontaneous vegetation. The use of white lupin , black oat + white lupin and black oat + oilseed radish showed to be a viable alternative for a higher grain yield, making the topdressing nitrogen fertilization unnecessary.

Assessment of micronutrient extractants from soils of Paraná, Brazil

In Brazil, plant-available micronutrients in the soil can be determined by several chemical extractants, the most common of which are dilute acid and chelating solutions. The purpose of this study was to assess the extractants 0.1 mol L-1 HCl, Mehlich-1, Mehlich-3 and DTPA for analysis of the micronutrients Cu, Zn, Fe, and Mn in soils from the state of Parana. In samples from 12 soils (0-20 cm layer), wheat was planted (Triticum aestivum), grown for 42 days after emergence, and then bean (Phaseolus vulgaris) for 38 days. At the end of each planting period, the soil was sampled again. All extractants tested to assess the availability of Cu, Zn, Fe, and Mn correlated with each other. The efficiency of the extractants HCl, Mehlich-3 and DTPA in assessing plant-available Cu was similar, unlike Mehlich-1, which proved less efficient. The extractants HCl, Mehlich-1 and Mehlich-3 were less efficient in estimating plant-available Zn and Fe, and the most indicated extractant is DTPA. The efficiency of the extractants HCl, Mehlich-1, Mehlich-3 and DTPA in assessing plant-available Mn in soils from Parana was similar.

Phosphorus and potassium fertilization in culture of soybean plants in the Oxisol

It is recommended to use phosphorus and potassium fertilization on soybean; however it has been common to verify the absence of effect on crop productivity, especially in no-tillage system. Thus, the study aimed to evaluate the effect of doses of superphosphate and potassium chloride in the leaf tissue nutrient content and yield of soybean growing in Oxisol. The experiment was installed in October 2011 in a randomized block design in split-bands with two factors (4x4), with four replications, totaling 64 plots, being Factor 1 with doses of superphosphate (0, 136, 331 and 700 kg ha-1) at sowing and Factor 2 with doses of potassium chloride (0, 160, 320 and 800 kg ha-1) released with cultivar Vmax RR (SYN 7059RR). In the experiment, the variables evaluated were Ca, Mg, K, P, S, Cu, Zn, Mn and Fe in leaf tissue and grain yield. The fertilization with superphosphate and potassium chloride do not interfere in leaf nutrient content and yield of soybean cultivar Vmax RR (SYN 7059RR) grown on an Oxisol of clayey with levels of P and K classified as high. In these cases, it is advisable to keep only the maintenance fertilization according to the values ​​of P and K exported by grain. Key words: Chemical fertilizer, tillage systems, organic mineral fertilizer, superphosphate, potassium chloride.