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Core Ideas Dividing a tillering N application into tillering and heading reduced wheat yield. Additional late‐season N application increased wheat protein concentration and dough quality. Late‐season N applications are economically unfit unless there is a reward for protein. Wheat yield and quality response to N management was similar across cultivars. There are opportunities to improve N management for wheat yield and quality in Southern Brazil. Nitrogen supply, environment, and cultivar determine yield and dough properties of hard red spring wheat (Triticum aestivum L.); however, the effects of broadcasting N fertilizer at heading, a growing practice in regions such as southern Brazil, have not been explored. The objectives of this study were to: (i) compare the current producer practice vs. alternative fertilizer N management strategies and (ii) quantify their interaction with cultivar and their effects on yield and its components and relevant dough properties. Field experiments were conducted using a complete factorial arrangement in a split‐plot design of three cultivars (main plots) and five N strategies (subplots) across three environments in southern Brazil. Overall, the current producer practice (all 70 kg N ha−1 applied at tillering) was appropriate to the targeted yield (3.5 Mg ha−1); splitting this fertilizer N rate into tillering and heading applications (either 35 kg N ha−1 on tillering + 35 kg N ha−1 on heading or 45 kg N ha−1 on tillering + 25 kg N ha−1 on heading) benefited protein concentration but reduced yield. Best N management resulted in the addition of one late‐season N application (70 kg N ha−1 on tillering + 23 kg N ha−1 on heading) positively impacting yield, protein concentration, dough extensibility, and alveogram index. In‐season N management is more relevant for grain quality than yield, more importantly if deductions from low protein are projected, or if premiums from increasing protein concentration exist, justifying a late‐season fertilizer N application.

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Soil microbial community and enzyme activity regulate carbon and nutrient cycling in soils. No-till has elevated levels of carbon at the soil surface compared to intensively tilled soils. The introduction of crop diversification in agricultural systems increases soil carbon protection and aggregate stability. Thus, the association of no-till with crop diversification may change the soil microbial distribution and enhance activity in comparison with tilled soils with no crop diversification. We tested this hypothesis assessing the soil microbial community and enzyme activity in a long-term (32 yr) experiment with contrasting soil management (no-tillage, (NT) and conventional tillage (CT)) and cropping systems in southern Brazil. Long-term NT increased microbial biomass at 0-5 cm. In contrast, soil microbial biomass was higher in deeper soil layers (10-30 cm) of CT. No-tillage and crop diversification increased the activity of β-glucosidase, acid phosphatase and N-acetyl-glucosaminidase. The benefits of an intensified/diversified crop rotation were offset by soil tillage. The higher abundance of PLFA groups at 0-5 cm and 10-30 cm of respective NT and CT soils were correlated with increased C and nutrient levels (N, Ca 2+ , Mg 2+) and decreased Al 3+. Highlights • Crop diversification increased the soil microbial biomass and individual PLFA groups. • No-till without crop diversification did not change microbial biomass. • No-till with crop diversification increased enzyme activity. • Subsoil fertility restricted microbial responses in a no-till Oxisol.

Em lavoura de arroz irrigado, é utilizada uma grande quantidade de agroquímicos que, dependendo da sua persistência a campo e toxicidade, podem contaminar corpos d’água e afetar organismos vivos. Com o objetivo de determinar o efeito de concentrações de campo dos herbicidas Clomazone, Quinclorac, Metsulfuron-methyl e Propanil na comunidade zooplanctônica (Cladocera, Copepoda e Rotifera), conduziu-se um experimento em viveiros de aqüicultura, de março a maio de 2005, na estação do outono. Nos dias 1°, 2°, 3°, 7°, 10°, 18°, 31° e 51° após a aplicação dos herbicidas, foram coletadas amostras de água para se determinarem parâmetros físico-químicos da água, concentração dos herbicidas e comunidade zooplanctônica. Os parâmetros médios da qualidade da água foram: oxigênio dissolvido (3,5mg L-1), temperatura (20,1°C), pH (6,0), dureza total (18mg L-1 de CaCO3) e alcalinidade total (9mg L-1 de CaCO3). A ordem decrescente de persistência dos herbicidas na água foi Clomazone = Quinclorac > Propanil > Metsulfuron-methyl, com média de 31, 31, 10 e 7 dias, respectivamente. Os resultados indicaram que os herbicidas provocaram poucas alterações na densidade de organismos dos grupos Rotifera e Copepoda (Adulto e Nauplio). A densidade do grupo Cladocera permaneceu baixa para todo o período experimental.

Resumo -O objetivo deste trabalho foi avaliar as relações da condutividade elétrica aparente (CEa), determinada por sensoriamento em tempo real, com os atributos do solo e com a produção vegetal, além de espacializar de forma indireta e em alta resolução os componentes da acidez de um Latossolo Vermelho distrófico no Sul do Brasil. O sensoriamento do solo foi realizado em duas áreas agrícolas, com o sensor Veris 3100. O solo foi amostrado à profundidade de 0,00-0,15 m, com trado calador. Avaliou-se o índice de vigor do milho (IV) com um sensor óptico, e a produtividade com sensores de produtividade e umidade. A associação dos atributos da acidez do solo com a produtividade do milho e com a CEa foi determinada por meio de análises de correlação e de componentes principais. A CEa relacionou-se ao IV e à produtividade de milho. Além disso, na área com qualidade química inferior, a CEa apresentou relação positiva com os conteúdos , matéria orgânica do solo e teor de argila.Termos para indexação: agricultura de precisão, condutividade elétrica, fertilidade do solo, manejo sítio-específico, matéria orgânica do solo, variabilidade espacial. High-resolution spacialization of an Oxisol's acidity attributes by on-the-go sensingAbstract -The objective of this work was to evaluate the relationships between the apparent electric conductivity (ECa), measured by on-the-go sensing, with soil attributes and plant production, besides indirectly mapping with high resolution, the main acidity attributes of an Oxisol in South Brazil. Soil sensing was performed in two crop fields using the Veris 3100 sensor. Soil was sampled at the 0.00-0.15-m soil depth using a hand auger. The corn vigor index (VI) was measured with an optical sensor, and yield was determined using grain yield and moisture sensors. contents, soil organic matter, and clay content.