ABSTRACT The objective of this work was to assess the effects of A. brasilense inoculation on seeds on the yield performance of maize and black oat as a function of nitrogen rate over a 3-year succession. The experiment was conducted from 2015 to 2018 under field conditions. Maize was grown for three growing seasons in rotation with two seasons of black oat at the same experimental site. A randomized block design with a split-plot arrangement was used. Main plots consisted of A. brasilense inoculation (inoculated and uninoculated plants) and subplots of four nitrogen rates (0, 40, 80, and 120 kg ha−1). Maize plants were evaluated for biometric parameters, yield, and yield components at flowering. Black oat plants were analyzed for dry matter yield at flowering. The inoculation of A. brasilense in maize and black oat seeds in succession does not promote productivity nor does it favor the nitrogen fertilization of these cultures.

ABSTRACT. In no-till (NT), liming and urea fertilization are performed on the soil surface, which can increase nitrogen (N) losses via ammonia volatilization. On the basis of N fertilization management, gypsum application provides a promising alternative for improving N uptake by plants. Therefore, the objective of this study was to evaluate the N behavior loss by NH3-N volatilization, the soil pH at a depth of 0 - 0.05 m, leaf N content, and N uptake by second-season corn after lime and gypsum application in a Rhodic Ferralsol under NT. Overall, the treatments consisted of a 4 × 4 factorial arrangement with four lime rates (0, 2.6, 5.4, and 8.1 Mg ha-1) and four gypsum rates (0, 4, 8, and 12 Mg ha-1). During the study period, second-season corn was cultivated for two years and fertilized with urea, for which the N losses through ammonia volatilization, soil pH, leaf N content, and N uptake values were quantified. The losses through ammonia volatilization were subjected to nonlinear regression using a logistic model, and the other variables were subjected to linear regressions. The lime applied by broadcasting on the soil surface in the NT increased the pH of the topsoil and increased N losses via NH3-N volatilization in the second-season corn. Further, the N losses in the NT treated with lime accounted for 58% of the applied N, which increased by 2.3 to 2.5% for each Mg ha-1 of lime applied. Therefore, lime or gypsum application did not improve the status of N in second-season corn in soils with low acidity and no S deficiency.

ABSTRACT The objective was to evaluate the effect of winter cover crops on the agronomic performance of maize during five crop seasons in a clayey Inceptisol with reduced mineral nitrogen (N) inputs. The treatments were seven single cover crops: white oats (Avena sativa L.), black oats (Avena strigose Schreb.), ryegrass (Lolium multiflorum L.), canola (Brassica napus L.), vetch (Vicia sativa L.), fodder radish (Raphanus sativus L. and red clover (Trifolium pratense L.); a mix (black oats + vetch and a fallow. During summer, in succession to the cover crops, maize was grown under no-tillage. The attributes were evaluated in two stages of maize development: flowering (morphological components and physiological maturation (yield components). Differences in morphologica and yield variables were observed in all crop seasons, with emphasis on grain yield, number of grains per row (NGR and ear length (EL). The use of vetch showed greater contribution to the development of maize in relation to the other cover crops used, promoting an increase in stem diameter (SD), E and NGR in all crop season and directly reflecting in higher grain yield. On the other hand, when maize was grown under cover crops commonly used in southern Brazil, such as ryegras and white oats, the yield was similar to fallow. The results showed that vetch promoted higher maize yields, probably by N mineralization and reinforce the hypothesis that cover crops in the off-season can aggregate benefits to crops in succession, especially in terms of nutrition.

ABSTRACT Novel fertilizer stabilization technologies are needed to decrease ammonia (NH3-N) losses and increase nitrogen use efficiency. Duromide + NBPT is a new technology that combines two molecules, Duromide and NBPT, whose propose is to increase the efficiency of the urease inhibitor NBPT in reducing NH3-N loss from urea. Preliminary results showed that Duromide + NBPT can be a more effective product than just NBPT, particularly under low soil pH and high-temperature conditions. This study aimed to compare the effects of urea + Duromide + NBPT, urea + NBPT, and conventional urea on soil N losses by NH3-N volatilization. The field experiment was conducted on a Latossolo Vermelho Distroférrico (Oxisol) in Campo Mourão, Paraná, Brazil, using a randomized complete block design with treatments arranged in a 2 × 3 factorial, comprising two N doses (45 and 90 kg ha-1) and three N fertilizers (urea + Duromide + NBPT, urea + NBPT, and conventional urea). The NH3-N volatilization data were subjected to nonlinear regression using a logistic model. The NH3-N losses varied according to dose and fertilizer, reaching up to 12.4 % of the applied N in the conventional urea treatment. Urea + Duromide + NBPT was more efficient than urea + NBPT in decreasing NH3-N volatilization. Compared to conventional urea at doses of 45 and 90 kg ha-1 of N, urea + Duromide + NBPT reduced NH3-N volatilization losses by 35 and 54 % and from urea + NBPT by 15 and 33 %, respectively. The new stabilizing technology Duromide + NBPT reduced NH3-N losses by up to 33 % compared to NBPT alone. Ammonia volatilization was influenced by soil moisture. The volatilization peak, observed after 18-19 days of N fertilizer application, was triggered by rainfall events.

ABSTRACT Oxisols ( Latossolos ) are widely distributed in tropical zones and generally characterized by high levels of surface and subsurface acidity. In Brazil, most Oxisols are managed under no-till conditions with surface application of acidity amendments. This study aimed to evaluate lime application strategies (incorporated and surface) for achieving the desired soil base saturation (BS%) levels (44, 60, 70, and 90 %) and the effect of phosphogypsum + lime application on soil chemical properties as well as wheat and corn yield in southern Brazil. Lime incorporation was more effective in reducing the soil acidity and increasing Ca2+ and Mg2+ despite a decrease in organic matter at the soil surface. Phosphogypsum application increased S-SO42- and Ca2+ availability throughout the deeper soil layers and reduced the Mg2+ content in the surface layer. Wheat yield under incorporated lime conditions increased with BS% up to 75, but there was no response to surface application. When phosphogypsum was applied, the wheat yield increased by 8.4 %. For corn, incorporated lime increased the yield up to 445 kg ha-1, which was equivalent to the yield after phosphogypsum application. An increase in the S-SO42- level was the main factor related to the increase in crop yields. In the short term, our results suggest that phosphogypsum applied along with lime is more appropriate than incorporating lime under no-till management conditions.

ABSTRACT Brazil is currently the leading country in no-till (NT) farming, particularly on Ferralsols (Latossolos), the most abundant soil type. These soils are characterized by subsurface acidity that cannot be effectively corrected by surface application of additives. In this situation, the use of phosphogypsum can be advantageous. This study aimed to assess the residual effects of lime and phosphogypsum application on a clayey Ferralsol, and four soybean and two wheat yields in southern Brazil. The area has been cultivated under no-till since 1975. The soil was limed to different base saturation (BS) levels (50, 60, 70, and 90 %) by surface application (SL) or lime incorporation (IL). Three combined treatments were also studied: (i) surface liming to 60 % BS plus standard (3.71 Mg ha-1) phosphogypsum dose (60G1), (ii) surface liming to 70 % BS + standard phosphogypsum dose (70G1); and (iii) surface liming to 70 % BS + double (7.42 Mg ha-1) phosphogypsum dose (70G2). Soil samples were collected 48 months after treatment. Soybean and wheat yield was not influenced by BS levels, however IL increased soybean yield in 2012/13, but reduced soybean and wheat yield in later crops. Phosphogypsum increased wheat yield by up to 12.8 % (2012 season) and 5.2 % (2015 season), but soybean was not influenced. Incorporated liming caused a decrease in soil Al3+ levels until 0.60 m depth, whereas SL decreased Al3+ levels until 0.30 m depth. Surface liming increased Mg2+ levels in the 0.40-0.60 m layer. Incorporated liming reduced soil organic matter in the surface layer. A double dose of phosphogypsum (7.42 Mg ha-1) had a greater residual effect in subsurface layers but caused a decrease in Mg2+ and K+ levels. Therefore, the standard phosphogypsum dose provided the best results. In the very clayey soil in subtropical environment, the effects of SL extend beyond surface layers and are preferable to those of IL, although production was not influenced by BS.

ABSTRACT The development of new fertilizer technologies to reduce nitrogen (N) losses from an agricultural system and to increase nitrogen use efficiency (NUE) is a global research objective. Controlled-release nitrogen fertilizers have shown great potential for reducing N losses and synchronizing N release according to crop demand, thereby improving the NUE. The objective of this study was to characterize controlled-release nitrogen fertilizers and compare them with conventional nitrogen sources in terms of N release, N loss via NH3 volatilization, and fertilizer effects on second-season corn. The field experiment was performed on an Ultisol in a randomized block design. The treatments consisted of two conventional nitrogen sources (urea and ammonium sulfate) and three brands of polymer-coated urea (PCU; Agrocote®, FortBlen®, and Kimcoat®). The variables N release and N loss by NH3 volatilization were subjected to nonlinear regression analysis using a logistic model and the Korsmeyer-Peppas model, respectively. Leaf N content and dry matter yield were subjected to the Tukey test, and the morphologies of the PCUs were observed by scanning electron microscopy (SEM). Electron micrographs revealed differences in the number of layers and the thickness of the coatings of the studied PCUs. FortBlen®, containing granules with single- or double-layer coatings with thicknesses ranging from 34.53 to 50.34 µm, promoted more gradual N release and reduced N-NH3 losses by 36.4 % compared with those observed with uncoated urea. Kimcoat® released approximately 98 % of the applied N within 24 hours, resulting in N-NH3 volatilization, and the responses in second-season corn were similar to those with uncoated urea. Although no benefits were observed in second-season corn for PCUs over uncoated nitrogen sources, some PCUs promoted more gradual N release and reduced N-NH3 volatilization, providing a promising alternative for environments prone to N loss.

Os custos de fertilizantes minerais têm aumentado consideravelmente nas últimas décadas, nesse cenário a adubação orgânica pode ser uma alternativa para diminuir custos e manter ou até mesmo aumentar as produtividades das culturas agrícolas. O objetivo do estudo foi avaliar a utilização de dejeto líquido suíno (DLS) associado à diferentes combinações de adubação mineral no desenvolvimento da cultura do milho, bem como o aspecto econômico. O experimento foi conduzido no município de Curitibanos, Santa Catarina, Brasil. Os tratamentos testados foram T1: NPK 09-33-12 + Ureia; T2: NPK 0-20-20 + DLS; T3: apenas DLS; T4: NPK 09-33-12 + DLS; T5: DLS + Ureia. Foram avaliados componentes morfológicos, de rendimento e análise econômica em duas safras (2014/15 e 2015/16). Para os componentes morfológicos, apenas o diâmetro de colmo e número de grãos por fileira foram influenciados significativamente, onde os tratamentos que envolveram maior adição de nitrogênio garantiram o aumento destas variáveis. O uso combinado entre adubo mineral e orgânico permitiu a redução dos custos e a manutenção de elevadas produtividades, sendo superiores à testemunha mineral na safra 2014/15. O uso exclusivo da adubação orgânica com DLS não se mostrou eficiente. A combinação de 50 m³ de DLS + ureia em cobertura foi a melhor opção para o manejo do DLS no milho.

The costs of mineral fertilizers have increased considerably in the last decades. In this scenario, organic fertilization can be an alternative to reduce costs and maintain and/or increase the productivity of grain crops. The objective of study was to evaluate the use of liquid swine manure (LSM) associated to different combinations of mineral fertilization in maize crop development, as well as the economic aspect. The experiment was carried out in the city of Curitibanos, Santa Catarina, Brazil. The treatments tested were T1: NPK 09-33-12 + Urea; T2: NPK 0-20-20 + DLS; T3: DLS only; T4: NPK 09-33-12 + DLS; T5: DLS + Urea. Morphological, yield and economics analysis components were evaluated in two seasons (2014/15 e 2015/16). For the morphological components, only stem diameter and number of grains per row were influenced significantly, where the treatments that involved greater nitrogen addition guaranteed the increase of these variables. The combined use of mineral and organic fertilizer allowed the reduction of costs and the maintenance of high yields, being superior to the mineral control in the 2014/15 season. The exclusive use of organic fertilization with LSM was not as efficient. The combination of 50 m³ of LSM + urea under topdressing was the best option for LSM management in maize.

Baixos teores de matéria orgânica no solo podem limitar o desenvolvimento da soja, devido a baixa disponibilidade de enxofre (S) no solo e pela alta demanda deste nutriente pelas plantas. Uma alternativa para complementar esta necessidade é a aplicação S foliar. O objetivo foi avaliar o efeito da aplicação de fertilizante foliar à base de enxofre na cultura da soja, em diferentes épocas e doses. Os tratamentos foram: (1) 0,0 kg ha-1 de S foliar; (2) 0,5 kg ha-1 de S foliar no estágio de início do florescimento (R1); (3) 0,5 kg ha-1 foliar no estágio de início do enchimento de grãos (R5.1); (4) 0,5 kg ha-1de S foliar nos estádios R1 e R5.1; (5) 1 kg ha-1de S foliar no estádio R1; (6) 1 kg ha-1de S foliar no estádio R5.1; (7) 1 kg ha-1de S foliar nos estádios R1 e R5.1, delineados em blocos ao acaso com 4 repetições. As variáveis respostas foram: massa de mil grãos, produtividade e teores de macro e micronutrientes nos grãos. A produtividade dos grãos aumentou 614 kg ha-1 com aplicação de S foliar em relação à testemunha. A dose que obteve a melhores resultados foi de 0,5 kg ha-1 aplicado nos estádios R3 ou R5.1. A utilização de enxofre elementar via foliar pode ser uma alternativa de complementação.

Low levels of organic matter in soil may limit the soybean crop development due to the low availability of sulfur (S) and the high demand of this nutrient by plants. The foliar fertilization is an alternative to supplement plant request. This study aimed at assessing the effect of applying foliar sulfur fertilizer in the soybean at different time and doses. The treatments studied were: (1) 0.0 kg ha-1 of S foliar; (2) 0.5 kg ha-1 of foliar S in beginning bloom (R1) stage; (3) 0.5 kg ha-1 of foliar at beginning seed (R5.1) stage; (4) 0.5 kg ha-1 of foliar S in R1 and R5.1; (5) 1 kg ha-1 of foliar S in R1; (6) 1 kg ha-1 of S foliar in R5.1; (7) 1 kg ha-1 of foliar S in R1 and R5.1 using randomized block design with 4 replicates. The variables analyzed were: one thousand grain mass, yield and the macro and micronutrient contents in the grains. The soybean yield increased 614 kg ha-1 with the application of foliar sulfur in relation to the control. The dose that obtained the best results was 0.5 kg ha-1 applied into the R3 or R5.1 stage. The use of elemental sulfur via foliar may be an alternative of sulfur supplementation.

ABSTRACT Brazilian soybean producers commonly apply maintenance potassium (K) fertilization during cultivation to restore the K taken up by plants; however, this measure can modify the morphophysiological plant characteristics, since the functions of K are closely related with plant growth and development. This study assessed the morphological changes in soybean plants in response to K rates, sowing fertilization, and the application periods of K fertilization in a Latossolo Vermelho eutroférrico (Oxisol) under a no-tillage system, located in the municipality of Floresta, Paraná. A randomized block design was used in the experiment with four replications in a fully crossed factorial design (5 × 2 × 2). The experiment was carried out in two growing seasons (2015/2016 and 2016/2017), with a total of 80 experimental units. The rates corresponded to the first factor (0, 40, 80, 120, and 160 kg ha-1 of K). The application periods (pre-sowing and post-sowing) were the second factor, and sowing fertilization (0 and 30 kg ha-1 of K) the third. The following variables were measured: shoot dry weight, leaf dry weight, stem dry weight, leaf area, specific leaf area, leaf area ratio, and leaf area index, and these biometric parameters were correlated with soybean yield. The results showed that plants well-supplied with K exploited the environment better and this may be reversed for higher yields since there were correlations between grain yield and the biometric parameters. At lower water availability, the biometric changes were more evident.