Productivity of corn and beans as affected by season and source of nitrogen / Produtividade de milho e feijão afetada pela época e fonte de nitrogênio

Enhanced-efficiency fertilizers, which provide a reduction in nitrogen (N) losses, can be a viable alternative for the anticipation of topdressing for the moment of sowing, besides reducing operations for the rural producer. This study aimed to determine the effect of the period of application of enhanced-efficiency nitrogen fertilizers on the grain yield of corn and common bean in the Cerrado region in the direct seeding system. The experiment was carried out during two crop seasons (2019/2020 and 2020/2021), under field conditions. The completely randomized blocks experimental design was used, being arranged in a 2x4+1 factorial, with four replicates. Treatments consisted of the combination of the following two periods of nitrogen application: at sowing and recommended (four open leaves of corn and third trefoil in beans); and of the four following types of nitrogen fertilizers: 1. urea + NBPT + Zeolite; 2. urea + B + Cu + Zeolite; 3. Super N; and 4. Urea. Additionally, a control treatment (without N) was included. Nitrogen values for application in the treatments were adjusted so that 150 kg ha¹ N was applied to the corn, cultivated in summer, and 90 kg ha N was applied to the common bean, cultivated in winter. It was concluded that nitrogen sources and period of nitrogen application did not affect corn grain yield, yield components, and common bean grain yield. The application of nitrogen in corn or common bean provided significant increases in crop grain yield.

Os fertilizantes com eficiência aumentada, que proporcionam redução das perdas de nitrogênio (N), podem ser alternativas viáveis para proporcionar a antecipação da adubação de cobertura para a semeadura e reduzir operações para o produtor rural. O objetivo do trabalho foi determinar o efeito da época de aplicação de fertilizantes nitrogenados de eficiência aumentada nas produtividades de grãos do milho e feijão-comum na região do Cerrado no sistema de semeadura direta. O experimento foi desenvolvido durante duas safras agrícolas, 2019/2020 e 2020/2021, em condições de campo. O delineamento experimental foi em blocos completos casualizados, no esquema fatorial 2x4+1, com quatro repetições. Os tratamentos constaram da combinação de duas épocas de aplicação de nitrogênio, semeadura e recomendada (quarta folhas aberta no milho e terceiro trifólio no feijão) com quatro tipos de fertilizantes nitrogenados (1. ureia + NBPT + Zeólita), 2. (ureia + B + Cu + Zeólita), 3. Super N e 4. Ureia). Adicionalmente foi incluído um tratamento controle (sem N). No milho, cultivado no verão, aplicou-se 150 kg ha² de N e no feijão-comum, cultivado no inverno, aplicou-se 90 kg ha¹ de N. Concluiu-se que as fontes nitrogenadas e a época de aplicação do nitrogênio não afetaram a produtividade de grãos da cultura do milho, os componentes de produção e a produtividade de grãos do feijão-comum. A aplicação de nitrogênio no milho ou no feijão-comum proporcionou incrementos significativos na produtividade de grãos das culturas.

Water depths and nitrogen rates on sugarcane growth and dry biomass accumulation

Irrigation and soil fertilization management are essential agricultural practices that improve the growth and development of sugarcane plants and, consequently, increase their production capacity, which is important for sugar and alcohol productions. In this context, the objective of this work was to evaluate the effect of water depths and nitrogen rates on the growth and dry biomass accumulation of sugarcane plants. The treatments consisted in four water depths (1,498; 1,614; 1,739; and 1,854 mm), five nitrogen rates (0; 20; 40; 80; and 120 kg ha-1) and five evaluation times. The experiment was conducted in a randomized block design with a split-split-plot arrangement and four replications, including the factors water depths, nitrogen rates, and days after planting. The dry biomasses of the plant pointer, leaves and culms, culm diameter, plant height, and number of plants were analyzed. The application of nitrogen increased the sugarcane biomass, mainly the pointer (with leaves) and dry culm biomass, and the number of plants. The highest dry culm biomass accumulation and dry leaf biomass were found at the end of the crop cycle for the treatment with the application of nitrogen rates of 80 and 120 kg ha-1. The increases in water depths applied increased the number of plants per linear meter, but the culm and dry leaf biomass did not happen.

Nitrogen and Stem Development: A Puzzle Still to Be Solved.

High crop yields are generally associated with high nitrogen (N) fertilizer rates. A growing tendency that is urgently demanding the adoption of precision technologies that manage N more efficiently, combined with the advances of crop genetics to meet the needs of sustainable farm systems. Among the plant traits, stem architecture has been of paramount importance to enhance harvest index in the cereal crops. Nonetheless, the reduced stature also brought undesirable effect, such as poor N-uptake, which has led to the overuse of N fertilizer. Therefore, a better understanding of how N signals modulate the initial and late stages of stem development might uncover novel semi-dwarf alleles without pleiotropic effects. Our attempt here is to review the most recent advances on this topic.

Deferred control of ammonium cross-feeding in a N2-fixing bacterium-microalga artificial consortium.

There is an increasing interest in the use of N2-fixing bacteria for the sustainable biofertilization of crops. Genetically-optimized bacteria for ammonium release have an improved biofertilization capacity. Some of these strains also cross-feed ammonium into microalgae raising additional concerns on their sustainable use in agriculture due to the potential risk of producing a higher and longer-lasting eutrophication problem than synthetic N-fertilizers. Here we studied the dynamic algal cross-feeding properties of a genetically-modified Azotobacter vinelandii strain which can be tuned to over-accumulate different levels of glutamine synthetase (GS, EC 6.3.1.20) under the control of an exogenous inducer. After switching cells overaccumulating GS into a noninducing medium, they proliferated for several generations at the expense of the previously accumulated GS. Further dilution of GS by cell division slowed-down growth, promoted ammonium-excretion and cross-fed algae. The final bacterial population, and timing and magnitude of algal N-biofertlization was finely tuned in a deferred manner. This tuning was in accordance with the intensity of the previous induction of GS accumulation in the cells. This bacterial population behavior could be maintained up to about 15 bacterial cell generations, until faster-growing and nonammonium excreting cells arose at an apparent high frequency. Further improvements of this genetic engineering strategy might help to align efficiency of N-biofertilizers and safe use in an open environment. KEY POINTS: • Ammonium-excreting bacteria are potential eutrophication agents • GS-dependent deferred control of bacterial growth and ammonium release • Strong but transient ammonium cross-feeding of microalgae.

Effect of hairy vetch cover crop on maize nitrogen supply and productivity at varying yield environments in Southern Brazil.

Cover crops play a critical role on conservation and sustainable agriculture due to their well-documented benefits on both soil and crop productivity. Inclusion of legumes (e.g., hairy vetch, Vicia villosa Roth) in the farming system can reduce the nitrogen (N) fertilizer needs for cereals such as maize (Zea mays L.) crop while maintaining or increasing its productivity. The aims of this research study were to quantify the effect of hairy vetch as a cover crop on: i) successor maize yield under varying yield environments (YEs) and fertilizer N rates, and ii) maize N status [N uptake, N nutritional index (NNI), and N fertilizer replacement value (NFRV)] at flowering time. Two field studies were carried out in Southern Brazil under varying YEs. The factors investigated were: YE (low, medium, and high), hairy vetch cover crop (with and without), and fertilizer N rate (0, 60, 120, 180, and 240 kg N ha-1). Under the combination of low YE and low fertilizer N rates (0-60 kg ha-1) with previous vetch, maize displayed the largest yield response and an improvement in its N status. The NNI determined at maize flowering was an efficient index of the vetch effect, increasing delta maize yield response (yield with- minus without-vetch) as the NNI reduced, with more than 10% delta yield response with NNI below 0.85. The NFRV of the hairy vetch represents potential N savings of 151 kg N ha-1 for the LYE, 95 kg N ha-1 for the MYE and from 59 to 45 kg N ha-1 for the HYE depending on the tested fertilizer N rate. The N coming from the legume cover crop in addition to the N fertilization was critical for supplying N to maize and boosting productivity across all YEs.

Morfogênese, características estruturais e acúmulo de forragem do Megathyrsus maximus BRS Zuri submetido a adubação nitrogenada / Morphogenesis, structural characteristics and forage accumulation of Megathyrsus maximus BRS Zuri subjected to nitrogen fertilization

A adubação nitrogenada possibilita aumentar a capacidade de suporte das pastagens, entretanto, o uso de elevadas doses pode causar efeitos negativos no crescimento de gramíneas forrageiras. A partir do pressuposto, objetivou-se avaliar a influência de doses crescentes de nitrogênio sob as características morfogênicas e estruturais, acúmulo de biomassa e eficiências de conversão e recuperação do nitrogênio em pastagem de Megathyrsus maximus cv. BRS Zuri. Foram testadas cinco doses de nitrogênio (0, 200, 400, 600 e 800 Kg de nitrogênio/ha) em delineamento experimental de blocos casualizados, com quatro repetições. Foi observado comportamento quadrático para as taxas de alongamento e aparecimento foliar, tempo de vida e o filocrono. Houve aumento no número de perfilhos e na produção de matéria seca quando as plantas foram submetidas à adubação, porém, tanto a eficiência de utilização quanto a recuperação aparente do nitrogênio reduziram linearmente com o aumento do nível de nitrogênio. O uso de fertilizante nitrogenado promoveu melhora nas características morfogênicas (P<0,05) exceto para taxa de alongamento de colmo e taxa de senescência foliar que se mantiveram estáveis. A Adubação com nitrogênio acelera as taxas de crescimento do Megathyrsus maximus cv. BRS Zuri. As respostas máximas nas variáveis morfogênicas, no número de folhas vivas e totais por perfilho são obtidas com doses próximas de 500 kg/ha, enquanto que doses variando de 600 a 647 kg/ha proporcionam maior tamanho de folha por perfilho, densidade populacional de perfilhos e produção de matéria seca. As eficiências de utilização e recuperação do nitrogênio reduzem com o aumento das doses de nitrogênio.(AU)

Nitrogen fertilization permits to increase the carrying capacity of pastures; however, the use of high doses can have negative effects on the growth of forage grasses. Therefore, the aim of this study was to evaluate the influence of increasing nitrogen doses on the morphogenic and structural characteristics, biomass accumulation, and nitrogen conversion and recovery efficiencies of Megathyrsus maximus cv. BRS Zuri. Five nitrogen doses (0, 200, 400, 600 and 800 kg of nitrogen/ha) were tested in a randomized block design with four replicates. A quadratic effect was observed for elongation rate, leaf appearance rate, leaf lifetime, and phyllochron. There was an increase in the number of tillers and in the production of dry matter when the plants were submitted to fertilization; however, both the efficiency of nitrogen use and the apparent recovery of nitrogen decreased linearly with increasing nitrogen level. The use of nitrogen fertilizer improved the morphogenic characteristics, except for stalk elongation rate and leaf senescence rate, which remained stable. Nitrogen fertilization accelerates the growth rates of Megathyrsus maximus cv. BRS Zuri. The maximum responses in the morphogenic variables number of live and total leaves per tiller are obtained with doses close to 500 kg/ha, while doses ranging from 600 to 647 kg/ha provide a larger leaf size per tiller, a higher tiller population density, and higher dry matter production. Nitrogen utilization and recovery efficiencies decrease with increasing nitrogen doses.(AU)

Morfogênese, características estruturais e acúmulo de forragem do Megathyrsus maximus BRS Zuri submetido a adubação nitrogenada / Morphogenesis, structural characteristics and forage accumulation of Megathyrsus maximus BRS Zuri subjected to nitrogen fertilization

A adubação nitrogenada possibilita aumentar a capacidade de suporte das pastagens, entretanto, o uso de elevadas doses pode causar efeitos negativos no crescimento de gramíneas forrageiras. A partir do pressuposto, objetivou-se avaliar a influência de doses crescentes de nitrogênio sob as características morfogênicas e estruturais, acúmulo de biomassa e eficiências de conversão e recuperação do nitrogênio em pastagem de Megathyrsus maximus cv. BRS Zuri. Foram testadas cinco doses de nitrogênio (0, 200, 400, 600 e 800 Kg de nitrogênio/ha) em delineamento experimental de blocos casualizados, com quatro repetições. Foi observado comportamento quadrático para as taxas de alongamento e aparecimento foliar, tempo de vida e o filocrono. Houve aumento no número de perfilhos e na produção de matéria seca quando as plantas foram submetidas à adubação, porém, tanto a eficiência de utilização quanto a recuperação aparente do nitrogênio reduziram linearmente com o aumento do nível de nitrogênio. O uso de fertilizante nitrogenado promoveu melhora nas características morfogênicas (P<0,05) exceto para taxa de alongamento de colmo e taxa de senescência foliar que se mantiveram estáveis. A Adubação com nitrogênio acelera as taxas de crescimento do Megathyrsus maximus cv. BRS Zuri. As respostas máximas nas variáveis morfogênicas, no número de folhas vivas e totais por perfilho são obtidas com doses próximas de 500 kg/ha, enquanto que doses variando de 600 a 647 kg/ha proporcionam maior tamanho de folha por perfilho, densidade populacional de perfilhos e produção de matéria seca. As eficiências de utilização e recuperação do nitrogênio reduzem com o aumento das doses de nitrogênio.

Nitrogen fertilization permits to increase the carrying capacity of pastures; however, the use of high doses can have negative effects on the growth of forage grasses. Therefore, the aim of this study was to evaluate the influence of increasing nitrogen doses on the morphogenic and structural characteristics, biomass accumulation, and nitrogen conversion and recovery efficiencies of Megathyrsus maximus cv. BRS Zuri. Five nitrogen doses (0, 200, 400, 600 and 800 kg of nitrogen/ha) were tested in a randomized block design with four replicates. A quadratic effect was observed for elongation rate, leaf appearance rate, leaf lifetime, and phyllochron. There was an increase in the number of tillers and in the production of dry matter when the plants were submitted to fertilization; however, both the efficiency of nitrogen use and the apparent recovery of nitrogen decreased linearly with increasing nitrogen level. The use of nitrogen fertilizer improved the morphogenic characteristics, except for stalk elongation rate and leaf senescence rate, which remained stable. Nitrogen fertilization accelerates the growth rates of Megathyrsus maximus cv. BRS Zuri. The maximum responses in the morphogenic variables number of live and total leaves per tiller are obtained with doses close to 500 kg/ha, while doses ranging from 600 to 647 kg/ha provide a larger leaf size per tiller, a higher tiller population density, and higher dry matter production. Nitrogen utilization and recovery efficiencies decrease with increasing nitrogen doses.

A minireview on what we have learned about urease inhibitors of agricultural interest since mid-2000s.

World population is expected to reach 9.7 billion by 2050, which makes a great challenge the achievement of food security. The use of urease inhibitors in agricultural practices has long been explored as one of the strategies to guarantee food supply in enough amounts. This is due to the fact that urea, one of the most used nitrogen (N) fertilizers worldwide, rapidly undergoes urease-driven hydrolysis on soil surface yielding up to 70% N losses to environment. This review provides with a compilation of what has been done since 2005 with respect to the search for good urease inhibitors of agricultural interests. The potential of synthetic organic molecules, such as phosphoramidates, hydroquinone, quinones, (di)substituted thioureas, benzothiazoles, coumarin and phenolic aldehyde derivatives, and vanadium-hydrazine complexes, together with B, Cu, S, Zn, ammonium thiosulfate, silver nanoparticles, and oxidized charcoal as urease inhibitors was presented from experiments with purified jack bean urease, different soils and/or plant-soil systems. The ability of some urease inhibitors to mitigate formation of greenhouse gases is also discussed.

Agronomic efficiency of NBPT as a urease inhibitor: A review.

Urea is the most widely used nitrogen (N) fertilizer, with a projected increase in annual demand of 1.5% in the coming years. After its application to soil, urea undergoes hydrolysis via the urease enzyme, causing increases in the soil pH in the surrounding area of the granules and resulting in NH3 losses that average 16% of N applied worldwide and can reach 40% or more in hot and humid conditions. The use of urease inhibitors is an effective way to reduce NH3 losses. Several compounds act as urease inhibitors, but only N-(n-butyl) thiophosphoric triamide (NBPT) has been used worldwide, being the most successful in a market that has grown 16% per year in the past 10 years. Only in the past three years other compounds are being commercially launched. In comparison to urea, NBPT-treated urea reduces NH3 loss by around 53%. Yield gain by NBPT usage is of the order of 6.0% and varies from -0.8 to 10.2% depending on crop species. Nitrification inhibitors usually increase NH3 volatilization and mixing them with urease inhibitors partially offsets the benefits of the latter in reducing NH3 loss. The efficacy of NBPT to reduce NH3 loss is well documented, but there is a need for further improvement to increase the period of inhibition and the shelf life of NBPT-treated urea.

Impacts of sugarcane agriculture expansion over low-intensity cattle ranch pasture in Brazil on greenhouse gases.

Sugarcane is a widespread bioenergy crop in tropical regions, and the growing global demand for renewable energy in recent years has led to a dramatic expansion and intensification of sugarcane agriculture in Brazil. Currently, extensive areas of low-intensity pasture are being converted to sugarcane, while management in the remaining pasture is becoming more intensive, i.e., includes tilling and fertilizer use. In this study, we assessed how such changes in land use and management practices alter emissions of greenhouse gases (GHG) such as CO2, N2O and CH4 by measuring in situ fluxes for one year after conversion from low-intensity pasture to conventional sugarcane agriculture and management-intensive pasture. Results show that CO2 and N2O fluxes increased significantly in pasture and sugarcane with tillage, fertilizer use, or both combined. Emissions were highly variable for all GHGs, yet, cumulatively, it was clear that annual emissions in CO2-equivalent (CO2-eq) were higher in management-intense pasture and sugarcane than in unmanaged pasture. Surprisingly, tilled pasture with fertilizer (management-intensive pasture) resulted in higher CO2-eq emissions than conventional sugarcane. We concluded that intensification of pasture management and the conversion of pasture to sugarcane can increase the emission factor (EF) estimated for sugarcane produced in Brazil. The role of management practices and environmental conditions and the potential for reducing emissions are discussed.

Nitrogen during the establishment period of Mombasa grass / Nitrogênio em períodos do estabelecimento de capim Mombaça

The aim of this study was to investigate the effect of nitrogen (N) concentration during the establishment period of Mombasa grass (Panicum maximum Jacq.). The experiment was conducted using four different N concentrations (0, 30, 60 and 90 kg N/ha) during the establishment period in order to evaluate the effect of nitrogen on the plant. These effects were assessed using different indexes, including the efficiency of nitrogen use and agricultural, physiological and nutritional efficiencies. We also determined the total dry matter and nitrogen accumulation in the plant. The recovery of applied N and the agronomic efficiency of Mombasa grass were found to be greater with increasing N concentrations, and all indexes tested were found to be affected by the concentration of applied N. Based on the indexes studied, 90 kg N/ha was found to be most suitable for Mombasa grass during the establishment period.(AU)

O presente trabalho teve como objetivo estudar o efeito de doses de nitrogênio (N) em pasto de capimMombaça (Panicum maximum Jacq.) durante o período de estabelecimento. Foi realizado experimento com quatro doses de N (0, 30, 60, 90 kg.ha-1), durante o período de estabelecimento, para avaliação do efeito do nitrogênio na planta, através de índices de eficiência de utilização, eficiência agronômica, fisiológica e nutricional, avaliou-se ainda a matéria seca total e o acúmulo de nitrogênio na planta. Concluiu-se que a recuperação do N aplicado e a eficiência agronômica pelo capim Mombaça aumentou com o incremento das doses. Sendo que, para todos os índices ocorreu influência das doses aplicadas. A dose de 90 kg de N.ha-1, com base nos índices estudados, é a mais indicada para o período de estabelecimento do capim-Mombaça.(AU)

Nitrogen during the establishment period of Mombasa grass / Nitrogênio em períodos do estabelecimento de capim Mombaça

The aim of this study was to investigate the effect of nitrogen (N) concentration during the establishment period of Mombasa grass (Panicum maximum Jacq.). The experiment was conducted using four different N concentrations (0, 30, 60 and 90 kg N/ha) during the establishment period in order to evaluate the effect of nitrogen on the plant. These effects were assessed using different indexes, including the efficiency of nitrogen use and agricultural, physiological and nutritional efficiencies. We also determined the total dry matter and nitrogen accumulation in the plant. The recovery of applied N and the agronomic efficiency of Mombasa grass were found to be greater with increasing N concentrations, and all indexes tested were found to be affected by the concentration of applied N. Based on the indexes studied, 90 kg N/ha was found to be most suitable for Mombasa grass during the establishment period.

O presente trabalho teve como objetivo estudar o efeito de doses de nitrogênio (N) em pasto de capimMombaça (Panicum maximum Jacq.) durante o período de estabelecimento. Foi realizado experimento com quatro doses de N (0, 30, 60, 90 kg.ha-1), durante o período de estabelecimento, para avaliação do efeito do nitrogênio na planta, através de índices de eficiência de utilização, eficiência agronômica, fisiológica e nutricional, avaliou-se ainda a matéria seca total e o acúmulo de nitrogênio na planta. Concluiu-se que a recuperação do N aplicado e a eficiência agronômica pelo capim Mombaça aumentou com o incremento das doses. Sendo que, para todos os índices ocorreu influência das doses aplicadas. A dose de 90 kg de N.ha-1, com base nos índices estudados, é a mais indicada para o período de estabelecimento do capim-Mombaça.

Nitrogen during the establishment period of Mombasa grass / Nitrogênio em períodos do estabelecimento de capim Mombaça

The aim of this study was to investigate the effect of nitrogen (N) concentration during the establishment period of Mombasa grass (Panicum maximum Jacq.). The experiment was conducted using four different N concentrations (0, 30, 60 and 90 kg N/ha) during the establishment period in order to evaluate the effect of nitrogen on the plant. These effects were assessed using different indexes, including the efficiency of nitrogen use and agricultural, physiological and nutritional efficiencies. We also determined the total dry matter and nitrogen accumulation in the plant. The recovery of applied N and the agronomic efficiency of Mombasa grass were found to be greater with increasing N concentrations, and all indexes tested were found to be affected by the concentration of applied N. Based on the indexes studied, 90 kg N/ha was found to be most suitable for Mombasa grass during the establishment period.

O presente trabalho teve como objetivo estudar o efeito de doses de nitrogênio (N) em pasto de capim-Mombaça (Panicum maximum Jacq.) durante o período de estabelecimento. Foi realizado experimento com quatro doses de N (0, 30, 60, 90 kg.ha-1), durante o período de estabelecimento, para avaliação do efeito do nitrogênio na planta, através de índices de eficiência de utilização, eficiência agronômica, fisiológica e nutricional, avaliou-se ainda a matéria seca total e o acúmulo de nitrogênio na planta. Concluiu-se que a recuperação do N aplicado e a eficiência agronômica pelo capim Mombaça aumentou com o incremento das doses. Sendo que, para todos os índices ocorreu influência das doses aplicadas. A dose de 90 kg de N.ha-1, com base nos índices estudados, é a mais indicada para o período de estabelecimento do capim-Mombaça.

Agronomic performance of castor under different growing conditions / Desempenho agronômico de mamona sob diferentes condições de cultivo

Castor has emerged as an oilseed species capable of meeting the demand of the Brazilian market. Thus, there is a need for studies to evaluate the different growing conditions that this species can be cultivated in order to subsidize their production. The study aimed to evaluate the influence of different growing conditions on agronomic performance of seven castor bean cultivars grown in Savanna-Pantanal ecotone region. The trial was conducted at Universidade Estadual de Mato Grosso do Sul, Aquidauana Campus. Treatments consisted of seven castor bean cultivars (BRS Energia, IAC-2028, IAC-Guarani, BRS Nordestina, BRS Paraguaçu, IAC-80 and IAC-226) and three growing conditions (with weed control and without topdress nitrogen; with topdress nitrogen at 80 kg ha-1 and with weed control; without weed control and absence of topdress nitrogen) in two agricultural years (2011 and 2012), arranged in randomized block design with three replications in factorial arrangement (7 x 3 x 2). The following variables were evaluated: plant height, stem diameter, number of bunches, number of fruits and fruit yield. The cultivars BRS Energia, IAC 2028, IAC Guarani and BRS Paraguaçu obtained greater fruit yield. Topdress nitrogen and weed control provided to cultivars the highest stem diameter, number of bunches, number of fruits and fruit yield.

A mamona vem se destacando como uma espécie oleaginosa capaz de suprir a demanda do mercado brasileiro. Desta forma, existe a necessidade de pesquisas que avaliem as diferentes condições de cultivo que esta espécie possa ser cultivada, a fim de subsidiar sua produção. O objetivo do trabalho foi avaliar a influência de diferentes condições no desempenho agronômico de cultivares de mamona cultivada na região do ecótono Cerrado-Pantanal. O experimento foi conduzido na Universidade Estadual de Mato Grosso do Sul, Campus de Aquidauana. Os tratamentos consistiram de sete cultivares de mamona (BRS Energia, IAC-2028, IAC-Guarani, BRS Nordestina, BRS Paraguaçu, IAC-80 e IAC-226) e três condições de cultivo (com controle de plantas daninhas e sem adubação de cobertura com N; com adubação de 80 kg ha-1 de N e controle de plantas daninhas; sem controle das plantas daninhas e ausência de adubação de cobertura com N) em dois anos agrícolas (2011 and 2012), dispostos em delineamento de blocos ao acaso com três repetições, em esquema fatorial (7 x 3 x 2). Foram avaliadas as seguintes variáveis: altura de plantas, diâmetro do caule, número de cachos, número de frutos e produtividade de frutos. As cultivares BRS Energia, IAC 2028, IAC Guarani e BRS Paraguaçu obtiveram maior produtividade de frutos. A adubação nitrogenada em cobertura e o controle de plantas daninhas proporcionaram às cultivares maior diâmetro do colmo, número de cachos, número de frutos e produtividade de frutos.

Ammonia volatilization losses in Tanzania grass fertilized with urea / Perdas de amônia por volatilização em capim-Tanzânia adubada com ureia

Gaseous losses are the main factors affecting the efficiency of nitrogenous fertilizers in pastures. To evaluate NH3-N volatilization losses in Tanzania grass fertilized with urea in autumn, spring and summer, a completely randomized design with repeated measurements over time and fifteen replicates was used. Plots were represented by urea levels (50; 100 and 150 kg ha-1 N) and subplots by time after fertilization (1; 2; 3; 6; 9; 12 and 15 days). The interaction between fertilization leveland time after urea application was significant for the accumulated NH3-N volatilization. Urea application leads to higher percentage N losses in the first three days after application. The average cumulative NH3- N loss for the three occasions (different seasons of the year) was 28%, 20% and 16% of N applied for fertilizer doses of 50; 100 and 150 kg ha-1 of N, respectively. The season of the year influenced NH3-N loss pattern and volume, with the lowest values recorded in spring, followed by summer and autumn. The cumulative NH3-N volatilization loss varies from 78 to 90% up to the third day after application of the total NNH3 loss.(AU)

Panicum maximum, nitrogen fertilizer, pastureAs perdas gasosas são os principais fatores de ineficiência do uso de fertilizantes nitrogenados nas pastagens. Com o objetivo de estimar a perda N-NH3 por volatilização foi realizado um experimento com capim Tanzânia adubada com ureia nas estações de outono, primavera e verão. Adotou-se um delineamento experimental inteiramente casualizado, com medidas repetidas no tempo com quinze repetições. Nas parcelas, as doses de N-ureia (50, 100 e 150 kg ha-1 de N-ureia) e, nas subparcelas, o período depois da adubação nitrogenada (1, 2, 3, 6, 9, 12 e 15 dias). A interação entre o nível de adubação e o período depois da aplicação de ureia foi significativa para a variável volatilização acumulada de N-NH3. A aplicação da ureia acarreta perdas percentuais mais elevadas de N nos três primeiros dias após a aplicação. A perda média acumulada de N-NH3 no período para as três estações do ano representou 28%, 20% e 16% do N aplicado nas adubações com 50, 100 e 150 kg ha-1 de N-ureia, respectivamente. A estação do ano influenciou no padrão e na quantidade das perdas, com menores valores encontrados na primavera, seguidos do verão e outono. A perda acumulada de N-NH3 por volatilização variou de 78 a 90% até o terceiro dia após aplicação do total perdido.(AU)

Ammonia volatilization losses in Tanzania grass fertilized with urea / Perdas de amônia por volatilização em capim-Tanzânia adubada com ureia

Gaseous losses are the main factors affecting the efficiency of nitrogenous fertilizers in pastures. To evaluate NH3-N volatilization losses in Tanzania grass fertilized with urea in autumn, spring and summer, a completely randomized design with repeated measurements over time and fifteen replicates was used. Plots were represented by urea levels (50; 100 and 150 kg ha-1 N) and subplots by time after fertilization (1; 2; 3; 6; 9; 12 and 15 days). The interaction between fertilization leveland time after urea application was significant for the accumulated NH3-N volatilization. Urea application leads to higher percentage N losses in the first three days after application. The average cumulative NH3- N loss for the three occasions (different seasons of the year) was 28%, 20% and 16% of N applied for fertilizer doses of 50; 100 and 150 kg ha-1 of N, respectively. The season of the year influenced NH3-N loss pattern and volume, with the lowest values recorded in spring, followed by summer and autumn. The cumulative NH3-N volatilization loss varies from 78 to 90% up to the third day after application of the total NNH3 loss.

Panicum maximum, nitrogen fertilizer, pastureAs perdas gasosas são os principais fatores de ineficiência do uso de fertilizantes nitrogenados nas pastagens. Com o objetivo de estimar a perda N-NH3 por volatilização foi realizado um experimento com capim Tanzânia adubada com ureia nas estações de outono, primavera e verão. Adotou-se um delineamento experimental inteiramente casualizado, com medidas repetidas no tempo com quinze repetições. Nas parcelas, as doses de N-ureia (50, 100 e 150 kg ha-1 de N-ureia) e, nas subparcelas, o período depois da adubação nitrogenada (1, 2, 3, 6, 9, 12 e 15 dias). A interação entre o nível de adubação e o período depois da aplicação de ureia foi significativa para a variável volatilização acumulada de N-NH3. A aplicação da ureia acarreta perdas percentuais mais elevadas de N nos três primeiros dias após a aplicação. A perda média acumulada de N-NH3 no período para as três estações do ano representou 28%, 20% e 16% do N aplicado nas adubações com 50, 100 e 150 kg ha-1 de N-ureia, respectivamente. A estação do ano influenciou no padrão e na quantidade das perdas, com menores valores encontrados na primavera, seguidos do verão e outono. A perda acumulada de N-NH3 por volatilização variou de 78 a 90% até o terceiro dia após aplicação do total perdido.

Ammonia volatilization losses in Tanzania grass fertilized with urea

p>Gaseous losses are the main factors affecting the efficiency of nitrogenous fertilizers in pastures. To evaluate NH sub>3 /sub>-N volatilization losses in Tanzania grass fertilized with urea in autumn, spring and summer, a completely randomized design with repeated measurements over time and fifteen replicates was used. Plots were represented by urea levels (50; 100 and 150 kg ha sup>-1 /sup> N) and subplots by time after fertilization (1; 2; 3; 6; 9; 12 and 15 days). The interaction between fertilization leveland time after urea application was significant for the accumulated NH sub>3 /sub>-N volatilization. Urea application leads to higher percentage N losses in the first three days after application. The average cumulative NH sub>3 /sub>-N loss for the three occasions (different seasons of the year) was 28%, 20% and 16% of N applied for fertilizer doses of 50; 100 and 150 kg ha sup>-1 /sup>of N, respectively. The season of the year influenced NH sub>3 /sub>-N loss pattern and volume, with the lowest values recorded in spring, followed by summer and autumn. The cumulative NH sub>3 /sub>-N volatilization loss varies from 78 to 90% up to the third day after application of the total N-NH3 loss. /p>

p>As perdas gasosas são os principais fatores de ineficiência do uso de fertilizantes nitrogenados nas pastagens. Com o objetivo de estimar a perda N-NH sub>3 /sub> por volatilização foi realizado um experimento com capim Tanzânia adubada com ureia nas estações de outono, primavera e verão. Adotou-se um delineamento experimental inteiramente casualizado, com medidas repetidas no tempo com quinze repetições. Nas parcelas, as doses de N-ureia (50, 100 e 150 kg ha sup>-1 /sup> de N-ureia) e, nas subparcelas, o período depois da adubação nitrogenada (1, 2, 3, 6, 9, 12 e 15 dias). A interação entre o nível de adubação e o período depois da aplicação de ureia foi significativa para a variável volatilização acumulada de N-NH sub>3 /sub>. A aplicação da ureia acarreta perdas percentuais mais elevadas de N nos três primeiros dias após a aplicação. A perda média acumulada de N-NH sub>3 /sub> no período para as três estações do ano representou 28%, 20% e 16% do N aplicado nas adubações com 50, 100 e 150 kg ha sup>-1 /sup> de N-ureia, respectivamente. A estação do ano influenciou no padrão e na quantidade das perdas, com menores valores encontrados na primavera, seguidos do verão e outono. A perda acumulada de N-NH sub>3 /sub> por volatilização variou de 78 a 90% até o terceiro dia após aplicação do total perdido. /p>

Ammonia volatilization losses in Tanzania grass fertilized with urea

p>Gaseous losses are the main factors affecting the efficiency of nitrogenous fertilizers in pastures. To evaluate NH sub>3 /sub>-N volatilization losses in Tanzania grass fertilized with urea in autumn, spring and summer, a completely randomized design with repeated measurements over time and fifteen replicates was used. Plots were represented by urea levels (50; 100 and 150 kg ha sup>-1 /sup> N) and subplots by time after fertilization (1; 2; 3; 6; 9; 12 and 15 days). The interaction between fertilization leveland time after urea application was significant for the accumulated NH sub>3 /sub>-N volatilization. Urea application leads to higher percentage N losses in the first three days after application. The average cumulative NH sub>3 /sub>-N loss for the three occasions (different seasons of the year) was 28%, 20% and 16% of N applied for fertilizer doses of 50; 100 and 150 kg ha sup>-1 /sup>of N, respectively. The season of the year influenced NH sub>3 /sub>-N loss pattern and volume, with the lowest values recorded in spring, followed by summer and autumn. The cumulative NH sub>3 /sub>-N volatilization loss varies from 78 to 90% up to the third day after application of the total N-NH3 loss. /p>

p>As perdas gasosas são os principais fatores de ineficiência do uso de fertilizantes nitrogenados nas pastagens. Com o objetivo de estimar a perda N-NH sub>3 /sub> por volatilização foi realizado um experimento com capim Tanzânia adubada com ureia nas estações de outono, primavera e verão. Adotou-se um delineamento experimental inteiramente casualizado, com medidas repetidas no tempo com quinze repetições. Nas parcelas, as doses de N-ureia (50, 100 e 150 kg ha sup>-1 /sup> de N-ureia) e, nas subparcelas, o período depois da adubação nitrogenada (1, 2, 3, 6, 9, 12 e 15 dias). A interação entre o nível de adubação e o período depois da aplicação de ureia foi significativa para a variável volatilização acumulada de N-NH sub>3 /sub>. A aplicação da ureia acarreta perdas percentuais mais elevadas de N nos três primeiros dias após a aplicação. A perda média acumulada de N-NH sub>3 /sub> no período para as três estações do ano representou 28%, 20% e 16% do N aplicado nas adubações com 50, 100 e 150 kg ha sup>-1 /sup> de N-ureia, respectivamente. A estação do ano influenciou no padrão e na quantidade das perdas, com menores valores encontrados na primavera, seguidos do verão e outono. A perda acumulada de N-NH sub>3 /sub> por volatilização variou de 78 a 90% até o terceiro dia após aplicação do total perdido. /p>

Tiller population density and tillering dynamics in marandu palisade grass subjected to strategies of rotational stocking management and nitrogen fertilization - doi: 10.4025/actascianimsci.v34i3.13739

The objective of this experiment was to evaluate tiller population density and the dynamics of the tillering process in marandu palisade grass subjected to strategies of rotational stocking management and nitrogen fertilization. Treatments corresponded to combinations between two targets of pre-grazing conditions (sward surface height of 25 and 35 cm) and two rates of nitrogen application (50 and 200 kg ha-1 year-1), and were allocated to experimental units according to a 2 x 2 factorial arrangement in a randomised complete block design, with four replications. The following response variables were studied: initial (TPDi), intermediate (TPDm) and final (TPDf) tiller population density as well as the rates of tiller appearance (TAR) and death (TDR) and the tiller population stability index (SI). TPDi was similar to all treatments, with differences in tiller population density becoming more pronounced as the experiment progressed, resulting in larger TPDf on swards managed at 25 cm pre-grazing height. Tiller death was larger on swards managed at 35 cm, with differences in tiller appearance being recorded only from February 2010 onwards. Stability of tiller population was higher on swards managed at 25 cm pre-grazing height. Overall, there was no effect of nitrogen on the studied variables, and the most adequate grazing strategy corresponded to the pre-grazing height of 25 cm, reg

Tiller population density and tillering dynamics in marandu palisade grass subjected to strategies of rotational stocking management and nitrogen fertilization / Densidade populacional e dinâmica do perfilhamento em capim-marandu submetido a estratégias de pastejo rotativo e adubação nitrogenada

The objective of this experiment was to evaluate tiller population density and the dynamics of the tillering process in marandu palisade grass subjected to strategies of rotational stocking management and nitrogen fertilization. Treatments corresponded to combinations between two targets of pre-grazing conditions (sward surface height of 25 and 35 cm) and two rates of nitrogen application (50 and 200 kg ha-1 year-1), and were allocated to experimental units according to a 2 x 2 factorial arrangement in a randomised complete block design, with four replications. The following response variables were studied: initial (TPDi), intermediate (TPDm) and final (TPDf) tiller population density as well as the rates of tiller appearance (TAR) and death (TDR) and the tiller population stability index (SI). TPDi was similar to all treatments, with differences in tiller population density becoming more pronounced as the experiment progressed, resulting in larger TPDf on swards managed at 25 cm pre-grazing height. Tiller death was larger on swards managed at 35 cm, with differences in tiller appearance being recorded only from February 2010 onwards. Stability of tiller population was higher on swards managed at 25 cm pre-grazing height. Overall, there was no effect of nitrogen on the studied variables, and the most adequate grazing strategy corresponded to the pre-grazing height of 25 cm, regardless of the nitrogen application rate used.

O objetivo deste experimento foi avaliar a densidade populacional e a dinâmica do perfilhamento em capim-marandu submetido a estratégias de pastejo rotativo e adubação nitrogenada. Os tratamentos corresponderam à combinação de duas metas de altura pré-pastejo (25 e 35 cm) e duas doses de aplicação de nitrogênio (50 e 200 kg ha-1 ano-1) em arranjo fatorial 2 x 2 alocadas às unidades experimentais segundo delineamento de blocos completos casualizados, com quatro repetições. Foram avaliadas a densidade populacional de perfilhos inicial (DPPi), intermediária (DPPm) e final (DPPf), as taxas de aparecimento (TAP), morte (TMP) e o índice de estabilidade (IE) da população de perfilhos. A DPPi foi semelhante para todos os tratamentos, com diferenças se acentuando ao longo da estação de crescimento, resultando em maior DPPf nos pastos manejados a 25 cm de altura pré-pastejo. A mortalidade de perfilhos foi maior nos pastos manejados a 35 cm, com diferenças em aparecimento sendo registradas somente a partir de fevereiro de 2010. Pastos manejados a 25 cm apresentaram maior estabilidade da população de perfilhos. Não houve efeito do nitrogênio nas variáveis analisadas, sendo que a melhor estratégia de manejo correspondeu à altura pré-pastejo de 25 cm, independente da dose de nitrogênio utilizada.