Fertilization of common bean (Phaseolus vulgaris) plants with amino-acids (AAs) near the beginning of flowering may increase productivity. This procedure is aimed to avoid waste and increase nutrient use efficiency at the end of the crop cycle, improving the leaf area in the translocation of these nutrients to the common bean. In order to test this hypothesis, a field experiment was conducted on a typic Eutrortox (Oxisol) in randomized block design, with three replicates. Four rates of a solution composed of amino-acids (6.8% glycine, 4.4% proline, 3.3% glutamic acid, 2.7% alanine, 1.9% arginine, 1.7% aspartic acid, 1.3% lysine, 1.3% histidine, and 1.0% leucine) applied 45 days after plant emergence were studied. There was no interaction between years of cultivation × amino-acids. However, the productivity of common bean was significantly influenced by the AAs rates, with the highest seed yield obtained at estimated concentration in 0.0094% of the product in foliar sprays. The increases in the rates resulted in increased foliar nitrogen (N) and zinc (Zn) concentrations and decreased sulfur (S) concentration. The macronutrient uptake was nitrogen>potassium>phosphorus>magnesium > calcium > sulfur (N > K > P > Mg > Ca > S), while for micronutrients it was iron>zinc>boron>copper>manganese (Fe > Zn > B > Cu > Mn). In the soil, the concentrations of organic carbon (C) and available P were negatively affected by the AAs rates.

This study evaluated the nutritional quality, yield, and storage protein modulation in soybean grains in response to levels and sources of sulfur (S) in a dystrophic Ultisol. We used five levels of S (0, 50, 100, 150 and 200 mg kg –1 ) and four sources of S (elemental S pastille - ESPA, gypsum - GY, gypsite - GI and elemental S powder - ESPO). Plants treated with 50 mg kg –1 of GY, GI, and ESPO and 200 mg kg –1 of ESPA had the largest grain yield values. Low S supply resulted in lower yields for all S sources tested. Sulfur deficiencies were observed at all levels for ESPA, resulting in lower concentrations of globulin and higher concentration of glutelin and albumin in the grains, possibly because the S content in the leaf was below the range adequate for soybean, leading to in lower yield values. In general, the application of S sources (GY, GI, and ESPO) increased all protein fractions. The results show that proper application of S is essential to optimize soybean yield and increase storage proteins in the grains. The granulometry of ESPA and ESPO fertilizers was a key factor for the availability of S to soybean plants. This study presents relevant information on S fertilization of soybeans, which could provide better grain nutritional quality and increased storage proteins with benefits to animal health.

Some silicate rocks are a rich source of potassium (K), with the possibility for use in agriculture. The present study aimed to evaluate the agronomic efficiency index (AEI) of nepheline syenite (NS) and phonolite (PN) rocks in comparison with potassium chloride (KCl) as a K source in maize production. An experiment was conducted in a greenhouse in Ilha Solteira, São Paulo, Brazil. A maize hybrid was grown in 8 L pots filled with 6 kg of soil with a low K concentration and contrasting physical attributes (medium and sandy texture). A completely randomized design in a 3 × 6 factorial scheme was used, consisting of three K sources (NS, PN, and KCl) and six rates (0, 50, 100, 150, 200, and 400 mg kg⁻¹) with four replications. All plants were harvested 45 days after emergence to evaluate biomass production, macronutrient (N, P, K, Ca, Mg, and S) concentration and uptake, stem diameter, and leaf chlorophyll index. After crop harvest, soil was collected for further chemical evaluation, which included organic matter (OM), pH, cation exchange capacity (CEC), H+Al, Al, sum of bases (SB), base saturation (BS), P, K, Ca, Mg, and S. In addition, AEI of NS and PN were also verified in relation to KCl. The application of NS and PN had a similar effect on soil chemical attributes (MO, pH, SB, CEC, and BS) as well as on the concentrations of K, Ca, Mg, and S, in both soils. The increase in NS and PN rates provided linear growth of shoot dry matter. Leaf macronutrient concentrations were similar for NS and PN compared to KCl. All three K sources (NS, PN, and KCl) increased K accumulation in maize plants. Maize treated with KCl had the largest AEI, followed by PN and NS. However, the results indicated similar AEI with both rocks as a K source for maize, especially with application of the highest K rates. This research demonstrated the efficiency of NS and PN as alternative K sources for maize.