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 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.

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.

ABSTRACT Brazilian agriculture contributes significantly to nitrous oxide (N2O) and methane (CH4) emissions, so the understanding of such emissions at the field is crucial for mitigation strategies. This study quantified the impact of N application and sheep grazing on the N2O and CH4 emissions from a subtropical Ferralsol under an integrated crop-livestock (ICL) management system. In a long-term experiment in southern Brazil, gaseous fluxes were measured during a year-long cycle of ryegrass (Lolium multiflorum) plus oats (Avena sativa) winter pasture and a summer crop of common beans (Phaseolus vulgaris). Three rates of urea-nitrogen (0, 75, and 150 kg ha-1) were applied to the winter-pasture, which was subjected to two sheep grazing levels (continuously grazed, and ungrazed). The experiment had a complete randomized block design with three replicates. Soil N2O and CH4 fluxes were measured with closed static-chambers (0.20 m high × 0.25 m in diameter). Nitrous oxide emission peaks occurred 28 days after N application and increased with N application rate. Accordingly, the cumulative N2O emissions averaged across grazed and ungrazed treatments increased from 0.45 kg ha-1 in the control soil to 1.78 and 2.10 kg ha-1 after application of 75 and 150 kg ha-1, respectively. The N2O emission factors were 1.7 and 1.1 % when the N rates were 75 and 150 kg ha-1, respectively. The cumulative average N2O emission for all N rates was 2.09 kg ha-1 in ungrazed pasture, but it was reduced by 62 % with grazing to 0.80 kg ha-1, perhaps because of a possible denitrification of N2O to N2 associated with soil compaction from trampling. Overall, fertilizer-N is an important source of N2O from soil under ICL based on sheep grazing, with emission factors consistent with the IPCC’s default of 1 % (0.3-3.0 %). Grazing reduced the emission of soil N2O, but the underlying cause of that reduction needs to be better understood.

In Brazil, more than 84% of N2O emissions and 74% of CH4 are produced by agriculture, and approximately 40% of the CO2 emitted originates from the use and change of land use and forest. It has been noticed a concern in several research institutions addressing this issue in order to improve the knowledge of the dynamics, as well as the main factors which drive the three main greenhouse gases (GHG) emissions. In this sense, sustainable technologies that follow the conservation agriculture premises show potential to mitigate the GHG emissions, as the no-tillage system (NTS), the use of cover crops, the use of integrated systems and other edaphic practices. Regarding the NTS, the CO2 retention in soil organic matter justifies the positive balance in soils managed under this system compared to conventional tillage. Usually undisturbed soils act as sink of CH4, however, the management NTS and conventional tillage still need more studies in order to evaluate its effects in N2O production. How the soil is managed, strongly affects the gases emission and the carbon balance, showing that the adoption of soil conservation practices, aiming to soil protection, are essential to mitigate the GHG

No Brasil, mais de 84% das emissões de N2O e 74% de CH4 são resultantes da agropecuária, e aproximadamente 40% do CO2 emitido tem origem do uso e mudança do uso da terra e florestas. Têm-se percebido uma preocupação em diversas instituições de pesquisa abordando essa temática, aprimorando o conhecimento da dinâmica e principais fatores que governam a emissão dos principais gases do efeito estufa (GEE). Nesse sentido, tecnologias sustentáveis que sigam as premissas da agricultura conservacionista apresentam potencial de mitigação na emissão de GEE, à poder citar o sistema de plantio direto (SPD), uso de plantas de cobertura, adoção de sistemas integrados, entre outras práticas edáficas. Em relação ao SPD, a retenção de CO2 na matéria orgânica do solo justifica o balanço positivo em solos manejados sob esse sistema em comparação ao cultivo convencional. Normalmente solos não perturbados atuam como dreno de CH4, no entanto os sistemas de manejo SPD e convencional ainda carecem de mais estudos, a fim de averiguar seus efeitos na produção de N2O. A forma como o solo é manejado influencia diretamente na emissão de gases e balanço de carbono, logo práticas conservacionistas que visam a proteção do mesmo, são fundamentais para mitigação de GEE

A atividade leiteira é fundamental para a pequena propriedade do sudoeste do Paraná. Este estudo teve como objetivo avaliar o efeito de épocas de corte de pastagem de aveia e azevém, com e sem adubação nitrogenada, sobre a produção de matéria seca e a qualidade da pastagem. O experimento foi conduzido em Pato Branco, PR, num delineamento de blocos ao acaso, com parcelas subdivididas e quatro repetições. Nas parcelas, fez-se uso de adubação nitrogenada de cobertura (0 e 100 Kg de N ha-1), na forma de ureia, e, nas subparcelas, foram avaliadas três épocas de corte de pastagem de aveia e azevém (30, 45 e 60 dias após a emergência). A aplicação de nitrogênio proporcionou um acúmulo de massa de 1133 Kg de MS ha-1, aos 45 dias após a emergência, próximo daquele considerado ideal para início de pastejo. O primeiro corte nessa época, combinado com o uso de nitrogênio, também favoreceu a capacidade de rebrota da pastagem, pois 30 dias após esse corte, o acúmulo de massa alcançou 2398 Kg de MS ha- 1. A adubação nitrogenada aumentou a quantidade de folhas de aveia na pastagem, fato que contribuiu para que o teor de proteína bruta fosse de 27%, indicando alta qualidade do material.

Dairy farming represents an important activity to small farmers, in south-west of Parana State, Brazil. The objective of this study was to evaluate the effect of the harvest period of oat and rye grass pastures, with and without nitrogen fertilization, on dry matter and pasture quality in order to determine the best time to start grazing. The experiment was carried out in Pato Branco, PR, in a randomized block design in split plot arrangement, with four repetitions. The main plot consisted of nitrogen fertilization levels (0 and 100 kg ha-1 of N), in the form of urea. The sub plots consisted of three cutting times of oat and rye grass pasture (30, 45 and 60 days after plants cropping up). The nitrogen applied provided dry mass accumulation of 1133 kg DM ha-1 45 days after emergence, close to the amount considered adequate to start grazing. The first cutting, at this time, in association with the use of nitrogen also influenced the pasture regrowth capacity, which was indicated by the dry mass accumulation of 2398 kg of DM ha-1 obtained 30 days after this cutting. Nitrogen fertilization increased the number of oat leaves , which contributed to the high level of crude protein content (27%), showing the high quality of the material.