Soybean Yield and Nutrition Grown on the Straw of Grain Sorghum Inoculated with Azospirillum brasilense and Intercropped with BRS Paiaguás Grass

The adoption of diversified agricultural systems that employ integrated cultural practices appears to be the way to sustainably intensify tropical agriculture. Our objectives were to evaluate the dry matter (DM) accumulation of sorghum inoculated with Azospirillum brasilense, with or without a nitrogen fertilization split, intercropped with palisade grass (Urochloa brizantha cv. BRS Paiaguás), and how these practices influenced the nutrition and development of soybean in succession. The design was a randomized complete block in a 2 × 2 × 3 factorial, consisting of sorghum monoculture cropped or intercropped with palisade grass, sorghum either inoculated or not with A. brasilense, and nitrogen applied at 120 kg ha-1 N only at sowing, only at topdressing, or split-30% at sowing and 70% at topdressing at the beginning of the panicle initiation stage. The residual impacts of these treatments on the following soybean crop were also evaluated. Higher DM yield occurred in sorghum inoculated with A. brasilense, however, this result varied by year. The sorghum-palisade grass intercrop produced a higher amount of straw than sorghum monoculture. The nutrition of soybean was adequate regardless of treatments, but grain yield was higher when the sorghum residue was inoculated. The inoculation of A. brasilense in sorghum intercropped with palisade grass increased yield. The nutrition of soybean was adequate regardless of the treatments, while grain yield was higher on the inoculated sorghum residues. The inoculation of A. brasilense in sorghum intercropped with palisade grass increased DM yield. The intercropping increased the production of biomass for animal grazing and DM for soil coverage. The inoculation of sorghum by A. brasilense and its intercropping with palisade grass contributed to higher soybean yield in succession.

GRAIN SORGHUM GROWN AS SECOND CROP AND INOCULATED WITH Azospirillum brasilense ASSOCIATED WITH NITROGEN FERTILIZATION

Nitrogen fertilization in crop sorghum during the off-season may have a lower cost-benefit ratio than expected, due to the residual effect of the predecessor crop. However, the use of growth-promoting bacteria can be an economical alternative to increase crop yield in the Cerrado. The objective was to evaluate the response of grain sorghum to nitrogen fertilization and its inoculation by A. brasilense. A complete randomized block design in a 5 x 2 factorial arrangement was used, with five replications of the following treatments: recommended amount of N (120 kg ha-1 of N-urea), divided into 0 %-100 %, 25 % -75 %, 50 %-50 % and 100 %-0 %, in sowing and coverage, respectively, and the control (without N); with and without inoculation via sorghum seed. The morphological and productivity components of the crop were evaluated. The application of 100 % of N in the sowing provided larger plants and the 50 %-50 % installment provided smaller plants. The plants did not respond to inoculation by A. brasilense. The yield components of sorghum grown in succession to soybean, rainfed, do not change due to A. brasilense inoculation and supply or installment of nitrogen fertilization.

Yield and Production Components of Corn Under Straw of Marandu Palisade Grass Inoculated With Azospirillum brasilense in the Low-Land Cerrado

The use of plant growth-promoting bacteria combined with Integrated Agricultural Production Systems (IAPS) has resulted in productivity increases in the Brazilian Cerrado region. Thus, the objective was to evaluate the effect of inoculating or not inoculating Azospirillum brasilense on corn and palisade grass seeds (Urochloa brizantha cv. Marandu) on growth, yield components, and dry matter yield of the aerial part and grains in an Oxisol cropped in ICLS and under a no-tillage system for 12 years in an irrigated area. The experimental design was a randomized block design with four replications. The treatments were composed of corn (monoculture) with inoculated seed, corn (monoculture) without inoculated seed, corn + palisade grass (intercropping) without inoculation, corn + palisade grass (intercropping) with inoculation in both seeds, corn + palisade grass (intercropping) with inoculation of corn seeds, and corn + palisade grass (intercropping) with inoculation of grass seeds. At the end of each production cycle, the yield and components of corn, corn straw biomass, and dry matter of palisade grass were evaluated. Considering the optimal conditions of soil provided by liming and fertilization at sowing and nitrogen applied in topdressing, the application of A. brasilense in corn seeds did not show its potential. Intercropped systems inoculated or not with A. brasilense on corn seeds increase grain yield, dry matter production of grass, and nutrient accumulation in the straw, providing greater sustainability to the Cerrado no-tillage system.

Teor proteico e mineral das silagens de sorgo consorciadas com gramíneas aditivadas com ureia

O conhecimento da dinâmica de cultivo do sorgo consorciado com forrageiras tropicais para produção de silagem é importante tanto para a nutrição animal, visando a qualidade do alimento, como para a sustentabilidade do sistema de produção agrícola. Seguindo essa lógica, o objetivo desta pesquisa foi avaliar os teores de proteína bruta e de macronutrientes das silagens de sorgo forrageiro em cultivo solteiro ou em consórcio com capim-marandu ou capim-mombaça, acrescidas de doses de ureia no momento da ensilagem. O delineamento experimental foi de blocos ao acaso, em fatorial 3 x 5, com os três tipos de silagem (sorgo forrageiro em monocultivo, consorciado com Urochloa brizantha cv. Marandu ou com o Megathyrsus maximus cv. Mombaça) e cinco doses de ureia como aditivo na ensilagem (0; 2,5; 5,0 e 7,5%). Foram determinados os teores de proteína bruta e de macronutrientes (P, K, Ca, Mg e S) antes e após o processo de ensilagem. A adição de doses até 7,5% de ureia no material a ser ensilado é eficiente em aumentar o teor de proteína bruta e de enxofre da silagem. As silagens de sorgo forrageiro consorciado com capim-marandu e capim-mombaça apresentaram maiores teores de proteína bruta, fósforo e potássio que a silagem de sorgo em monocultivo quando não há adição de ureia.