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Limestone is the most widely used agricultural input for soil acidity correction and calcium (Ca) and magnesium (Mg) fertilization. However, other materials have the potential to fulfill these purposes, such as steel slags, also known as silicates. Silicates have higher solubility than limestone, serving as agents for increase pH in no‐till, in addition to being a source of Ca, Mg, and silicon (Si). This study aimed to compare the effects of surface application of dolomitic lime and calcium magnesium silicate on soil chemical properties, soybean [Glycine max (L.) Merr.] nutritional status, and grain yield under no‐till. The experiment was installed in the northwest Paraná State, Brazil, on a Rhodic Eutrustox. Lime and silicate rates were applied by broadcasting before the sowing of soybean. Silicate treatment increases soil Ca2+, pH, and base saturation up to a depth of 0.10 m. By contrast, liming effects on soil chemistry were restricted to the 0.05 m top layer after 24 months of application. The acidity correction and Ca2+ supply to greater soil depths and the increased leaf Si as a beneficial element provided by silicate treatment contributed to increasing soybean yield in the 2018/2019 and 2019/2020 seasons. Lime application, regardless of the rate, did not improve soybean yield. Waste from the steel industry can be used as acidity correctives and source of Si, Ca, and Mg, improving the agronomic performance of soybean. Core Ideas: Silicate is more efficient in maintaining soil fertility compared to lime.Changes in soil fertility were observed up to a depth of 0.10 m after 24 months.Silicate increases silicon content in soybean leaf.Surface application of silicate increased soybean yield up to 43%.Soybean yield did not improve with lime. [ABSTRACT FROM AUTHOR]

The yield gain of soybean inoculated with Bradyrhizobium spp. or co-inoculated with Bradyrhizobium spp. and Azospirillum brasilense is variable. Inoculants can be applied in the sowing furrow or via seed treatment. There is a gap in our understanding of the efficacy of different inoculation methods. This study aimed to assess the agronomic efficiency of soybean inoculated and co-inoculated with Bradyrhizobium spp. and A. brasilense by different methods. The study was conducted in Paraná State, Brazil, in two seasons. Five treatments were tested: control; seed treatment with Bradyrhizobium spp. (SBr), seed treatment with Bradyrhizobium spp. + A. brasilense (SBr+Az), in-furrow treatment with Bradyrhizobium spp. (FBr), and in-furrow treatment with Bradyrhizobium spp. + A. brasilense (FBr+Az). Shoot dry weight, grain nitrogen content and grain yield were lower in 2018/19. In 2017/18, FBr+Az increased nodule number and dry weight compared with SBr. FBr+Az promoted a 47% increase in pods per plant compared with the control in both seasons. Regardless of season, grain nitrogen content was higher with FBr+Az (mean relative increase of 27%). FBr+Az was superior to SBr+Az in 2017/18, with a 12% increase in yield. Inoculation and co-inoculation improve morphological traits and soybean yield. In-furrow inoculation is more efficient than seed treatment. [ABSTRACT FROM AUTHOR]

Improvements in nitrogen use efficiency (NUE) in corn production systems are necessary, to decrease the economic and environmental losses caused by loss of ammonia volatilization (NH3-N). The objective was to study different nitrogen (N) fertilizer technologies through characterization of N sources, NH3-N volatilization losses, and their effects on the nutrient concentration and yield of corn grown in clayey and sandy soils in south Brazil. The treatments consisted of a control without N application as a topdressing, three conventional N sources (urea, ammonium sulfate, and ammonium nitrate + calcium sulfate), and three enhanced-efficiency fertilizers [urea treated with NBPT + Duromide, urea formaldehyde, and polymer-coated urea (PCU) + urea treated with NBPT and nitrification inhibitor (NI)]. The losses by NH3-N volatilization were up to 46% of the N applied with urea. However, NI addition to urea increased the N losses by NH3-N volatilization by 8.8 and 23.3%, in relation to urea alone for clayey and sandy soils, respectively. Clayey soil was 38.4% more responsive than sandy soil to N fertilization. Ammonium sulfate and ammonium nitrate + calcium sulfate showed the best results, because it increased the corn yield in clayey soil and contributed to reductions in NH3-N emissions of 84 and 80% in relation to urea, respectively. [ABSTRACT FROM AUTHOR]

Large amounts of waste are produced daily by several industrial branches in Brazil, many of which can be used in agriculture. Applying nutrient-containing waste onto soil might minimize dependence on chemical mineral fertilizers, contributing to sustainable agriculture. Some of this waste increases soil pH, similar or even superior to that of limestone, providing opportunities for use in acidic soils. Different industrial waste may have elements that alter the electric charge of clay surfaces, which may alter soil physical characteristics related to dispersion and flocculation and consequently soil aggregation. Therefore, the presence of sodium may cause the dispersion of clays and calcium-containing waste, as its components may improve aggregation. The application of industrial waste can add heavy metals to the soil and, consequently, environmental problems if performed without strict regulations. Brazil has large industrial and agricultural areas, to which waste can be applied to supply part or all of the nutritional plant demand. To be recommended as economically effective and environmentally safe, a thorough waste analysis, chemical characterization of the soil, and knowledge of the nutritional requirements of the crop to be grown are required. [ABSTRACT FROM AUTHOR]

Emission of nitrous oxide (N2O) can be reduced using enhanced efficiency nitrogen fertilizers (EEFs), such as urease inhibitors and coating technologies. In this study, we evaluated the potential of EEFs to reduce N2O emissions in maize in a clayey Inceptisol subjected to no-till management under summer subtropical conditions, in southern Brazil. The EEF sources used included urea containing N-(n-butyl) thiophosphoric triamide (UR-NBPT), polymer-coated urea (UR-pol), in addition common urea (UR), nitrate (CN) and control treatment without the application of nitrogen fertilizer. N2O emissions were assessed using the static chamber method during one maize season and analyzed through non-linear regression, using a logistic model. The accumulated emission was 0.817, 0.613, 0.457 and 0.393 kg N2O ha−1, for CN, UR, UR-pol and UR-NBPT, respectively. The maximum daily emission of N2O did not vary between amidic forms, however for CN it occurred on the 4th day after application (DAA), while for urea forms it occurred on average at 5.3 DAA. The average N2O emission factor (FE-N2O) was 0.51%, approximately half the standard factor proposed by the Intergovernmental Panel on Climate Change (IPCC), which is 1%. The application of nitrogen increased the maize yield in relation to the control, but the sources of nitrogen did not differ, with an average yield of 10,455 kg ha−1. Based on our findings, the use of UR-NBPT and UR-pol in subtropical agroecosystems provides environmental benefits, by reducing N2O emissions in comparison with conventional nitrogen fertilizers (CN and UR), however, the EEFs did not offer agronomic advantages in maize yield. [ABSTRACT FROM AUTHOR]

Knowing the nutrient removal by soybean grain harvest in different varieties, locations, and over time is essential to correctly adjust agronomic recommendations, update farmers' practices, and increase nutrient use efficiency. A field-based research trial was carried out to assess macronutrients [nitrogen (N), phosphorus (P), potassium (K), magnesium (Mg), calcium (Ca), and sulfur (S)] removed in grain by modern soybean varieties from southern Brazil introduced between 2007 and 2016. We examined changes between our set of modern varieties and a dataset of historical values encompassing a wide range of varieties introduced before 2007. Moreover, we undertook a synthesis analysis using scientific literature published after 2007 to investigate nutrient removal by grain among modern Brazilian soybeans and a dataset that included field trials from Argentina, United States, and India. There were no yield gains across the years for modern soybean varieties introduced among 2007 and 2016 in Brazil, although the grain N and Mg concentrations decreased. Modern Brazilian soybeans increased nutrient removal compared with that by soybeans historically planted in Brazil, with 11.1, 26.9, 45.0, and 31.6% more N, P, K, and Mg removed, respectively. Our results indicated that soybean growing in Brazil removed 4.3% less N relative to the values reported in the literature dataset, whereas K removal was 21.4% greater. A significant difference was also recorded for high-yield soybean varieties, and Brazilian varieties removed 11.8% less N and 8.6% more K than varieties in the literature dataset. No differences were found among locations for P removal, averaging 4.9 kg Mg–1 grain. In conclusion, this study indicates that the amounts of nutrients removed by modern soybean varieties were greater relative to the historical values recorded in Brazil, excluding Ca and S. Nonetheless, in the middle to long term (10 years), a significant impact of plant breeding on grain nutrient concentration was recorded only for N and Mg. The difference in nutrient removal patterns between Brazil and other countries indicates an integrated effect of management, genotype, and environment on nutrient removal. These findings provide guidance for optimal nutrient management and specific information for plant breeding programs to understand nutrient variability. [ABSTRACT FROM AUTHOR]

Nutrient leaf application is complementary to soybean nutritional management, mainly at maturity, when plants present high nutritional demand and high nutrients and photoassimilate translocation rates for seed production. The aim of this research was to evaluate the agronomic performance, physiological quality, and nutritional contents of soybean seeds after application of different rates (0, 0.50, 1.0, 1.5, 2.0, and 2.5 kg ha−1) of foliar fertiliser containing calcium (20%) and boron (4%) at the R3 stage (onset of pod formation). This research was carried out in two sites (Guaragi and Floresta) both in Parana State, Brazil, in randomised complete blocks with 4 replicates. Calcium and boron leaf application increased grain sulphur and nitrogen levels (Guaragi) but reduced phosphorus and magnesium (Floresta). Regarding physiological quality, foliar fertilisation increased the index of germination speed. The yield and number of pods increased up to the rate of 0.6 and 1.2 kg ha−1 of leaf fertiliser in Floresta. Foliar fertilisation with calcium and boron showed advantages, however, results depended on the site, indicating different levels of soil fertility and climatic characteristics. [ABSTRACT FROM AUTHOR]