O preparo do solo favorece o desenvolvimento do sistema radicular e cria condições adequadas para o desenvolvimento das plantas. Todavia, o intenso uso de máquinas e implementos pode afetar a resistência do solo à penetração (RP) e a manutenção da cobertura vegetal morta na superfície do solo. O objetivo deste trabalho foi avaliar a influência dos sistemas de preparo convencional e reduzido sobre a RP e a cobertura vegetal morta em um Latossolo vermelho de textura muito argilosa, em condições de baixa umidade, além de comparar três métodos na estimativa da palhada. A RP foi avaliada por meio do uso de um penetrômetro de impacto modelo IAA/Planalsucar – Stolf na profundidade de 0,0-0,6m e a cobertura vegetal morta por meio da captura e análise de imagens. Houve diferença significativa entre os tratamentos nas profundidades de 0,15-0,20 m, 0,45-0,50 m e 0,50-0,55 m do solo. Ambos os sistemas de preparo fizeram com que o solo apresentasse de baixa a muito alta RP nas profundidades avaliadas. Verificou-se que os métodos para estimar a cobertura morta do solo não diferiram significativamente entre si e que, no momento anterior ao preparo, havia mais de 91% do solo coberto com palhada. Após as operações mecanizadas, houve maior redução de palha quando foi empregado o sistema de preparo convencional.

This study was carried out to determine whether the yield of soybean cultivars and the severity of Asian Soybean Rust (ASR) are influenced by foliar spray of silicon exclusively or along with a fungicide mixture, as well as the economic viability of their use for a sustainable crop. The experiment was performed in randomized-block design, five replicates, two soybean cultivars and (2×6) + 2 factorial arrangements: S1 (AlSi at R1 + R4); S2 (AlSi at R1 + R5.1); S3 (AlSi at R1 + FM at R4); S4 (FM at R1 + AlSi at R4); S5 (AlSi at R1 + FM at R5.1); S6 (FM at R1 + AlSi at R5.1); NC and PC (negative and positive control). The economic evaluation and sensitivity analysis were undertaken for Anta 82 RR. There was no interaction effect between the factors, and cultivar CD 2737 had a higher yield. ASR was less severe in CD 2737, and S3 and S5 provided the lowest disease severity. Exclusive spray of aluminum silicate was able to reduce the number of lesions with uredinia, open uredinia and uredinia per lesion. S3 increased grain yield, resulting in higher revenues and a 66.1% gross margin. Sensitivity analysis revealed that S3 was profitable in all scenarios.

Maize and forage sorghum crops have a relevant economic importance in Midwest Brazil and there is a need for more information for their intercropping as a strategy for the farmers to reduce inputs. The objective of this work is evaluate if forage sorghum and maize intercropping effects agronomic traits, the bromatological characteristics of silage from the consortium at different times of silo openings, and the economic viability of all crop systems. This experiment was carried on in the field with seven treatments, consisting of monoculture and intercropping of corn and sorghum hybrids. Monoculture of sorghum Agri 001 and maize Agri 320, as well as in maize Agri 320, Agri 340 and Agri 104 intercropped with sorghum Agri 001 had the highest biomass yield. Intercropped maize did not have lodging, reduction in height, nor decrease in the first ear height in relation to the intercropped plants. Maize hybrids intercropped with sorghum led to a better fermentation pattern of silages, reducing ammonia concentrations. However, due the higher contents of NDF and the lower TDN contents of sorghum, nutritional values of intercropped silages were generally smaller than when they were composed only with maize. It was observed that the monoculture of sorghum Agri 001 for silage showed a higher profit compared to the other treatments.

The mineral nutrition of forage species is essential for the maintenance of sustainable livestock systems, since it can increase animal productivity per area. Panicum maximum is considered nutritionally demanding. However, the behavior of modern cultivars under nitrogen fertilization is unknown. The objective of this study was to evaluate the effects of increasing doses of nitrogen (N) on the structural characteristics, forage biomass, and crude protein (CP) of cultivar BRS Tamani. The experimental design was randomized blocks, and the treatments consisted of six N doses (0, 62.5, 125, 250, 375, and 500 N mg∙dm-3) using ammonium sulfate (AS) fertilizer, divided into three coverage applications under greenhouse conditions. Three cuts were made from all treatments, separated by an interval of 30 days. The interval between cuts was considered a split-plot effect. There was no interaction effect between the cuts and AS doses for the number of leaves tiller-1 or crude protein. However, there was an interaction effect for the leaf length, number of tillers, and biomass. The use of doses between 280 and 380 mg N∙dm-³ influenced the structural characteristics of the canopy and biomass of 'BRS Tamani' grass. The highest CP value was recorded in the first cut.

O uso intensivo de máquinas agrícolas no cultivo de plantas para produção de silagem pode ocasionar a compactação do solo e comprometer o desenvolvimento das plantas. O objetivo deste trabalho foi avaliar os efeitos do cultivo de milho e guandu na resistência do solo à penetração (RP), cultivados em solo preparado de forma convencional. Os dados de RP foram obtidos por meio de um penetrômetro de impacto modelo IAA/Planalsucar, até os 0,4 m de profundidade. Foram coletadas amostras de solo para se avaliar a umidade gravimétrica do solo. Os valores de resistência mecânica do solo à penetração foram transformados em unidade padrão de pressão (MPa). O delineamento experimental empregado foi de blocos ao acaso, com dois tratamentos representados pelos cultivos de milho e guandu em área de 2000 m² cada, divididos em 10 repetições e 4 perfis analisados em cada repetição. Os valores encontrados nos dois tratamentos foram críticos ao desenvolvimento vegetal e o solo cultivado com guandu apresentou menor resistência à penetração em quase todos os estratos analisados. Os resultados obtidos demonstraram que o potencial do guandu em descompactar o solo foi superior ao do milho.