Dynamics of nitrogen concentration on intercropped ryegrass.

The dynamics of nitrogen (N) in ryegrass intercropped with different forage species with regard to dry matter (DM) accumulation within an agroecological transition system was evaluated. Annual ryegrass was intercropped with black oats (RY + BO), white clover (RY + WC) and forage peanut (RY + FP). The experimental design was completely randomized, with three replications. The study applied the N dilution model for plant tissue which comparatively uses modifiable factors of the environment at optimal levels. The model shows decline in N concentration due to the DM accumulation of temperate grass pastures. Data were compared to model by the root mean square deviation analysis. Dilution coefficient (β), used in all pasture samples, was lower than -0.60. Highest N concentration decline in plant tissues, due to DM accumulation, occurred in RY + WC pastures (β = -0.94), followed by RY + FP (β = - 0.86) and RY + BO (β = - 0.67), respectively. Ryegrass intercropped with white clover showed the highest N content in plant tissue, with a nitrogen nutrition index close to the proposed model

COMPORTAMENTO INGESTIVO DE VACAS EM LACTAÇÃO EM PASTAGEM CONSORCIADA NO PERÍODO ESTIVAL

Resumo A pesquisa teve como objetivo estudar o comportamento ingestivo de vacas da raça Holandesa em lactação, durante o período estival, em pastagens constituídas por capim-elefante (Pennisetum purpureum Schum.) e espécies de crescimento espontâneo, consorciadas com trevo branco (Trifolium repens L.) ou amendoim forrageiro (Arachis pintoi Krap. & Greg.). Foram feitas avaliações em três pastejos (dezembro, fevereiro e abril). Para cada avaliação utilizaram-se seis vacas entre o segundo e o quinto mês de lactação. O registro de dados foi realizado das 18 às 06 horas e das 08 às 16 horas, a cada 10 minutos. Os parâmetros comportamentais observados foram o tempo de pastejo em capim-elefante, pastejo das espécies estabelecidas na entrelinha, pastejo total (pastejo do capim-elefante e da forragem na entrelinha), ruminação e ócio. O tempo médio de pastejo da entrelinha foi de 3h 48 min e 2h 9 min para os consórcios com o trevo branco e amendoim forrageiro, respectivamente, sendo superior (P<0,05) para a primeira mistura de forrageiras. O tempo médio de pastejo diário do capim elefante foi de 5h 32 min e 6h 27 min, para os respectivos consórcios, não havendo diferença entre eles. Para os tempos de ruminação e ócio houve similaridade entre as pastagens estudadas. Palavras-chave: capim-elefante; etologia; pastejo rotacionado; valor nutritiv

Effect of Nitrogen Topdressing Fertilization and Inoculation of Seeds with Azospirillum brasilense on Corn Yield and Agronomic Characteristics

Biological nitrogen fixation and plant hormone synthesis promoted by Azospirillum spp. bacteria play a role in enhancing crop productivity and reducing losses. This may constitute a strategy to enhance crop productivity and reducing losses, thereby increasing nitrogen fertilization efficiency. This research aimed to evaluate the effects of Azospirillum brasilense Ab-V5 and Ab-V6 strain inoculation and nitrogen fertilization on the agronomic characteristics and productivity of two maize hybrids (Zea mays L.) AS 1572 and AG 9030. Experiments were carried out at Santa Maria, RS, Brazil in the 2013/2014 and 2014/2015 growing seasons using a 2 &times; 2 &times; 5 factorial arrangement to distribute two maize hybrids, inoculated, or not, with Azospirillum brasilense, and five nitrogen doses (0, 60, 120, 240, and 480 kg ha&minus;1). Kernel yield, mass, and dimensions, as well as kernel number on the cobs, stalk diameter, plant height, ear insertion height, prolificacy, nitrogen use efficiency (NUE), and their correlations were measured. Compared to uninoculated plants, higher kernel yield (p &lt; 0.05) was observed for AS 1572 hybrid when inoculated with A. brasilense, with an increase of 0.978 Mg ha&minus;1 or 10.95%. This effect was primarily due to the higher NUE rate and the increase (p &lt; 0.05) in the number of kernels per cob. The AG 9030 hybrid showed no response to inoculation. A. brasilense inoculation increased the NUE rate of the AS 1572 hybrid in the condition N zero dose at N 60 kg ha&minus;1 dose. Nitrogen fertilization increased crop productivity, notably by raising kernel mass and other productivity components, but reduced the NUE rate. The maximum technical efficiency obtained for the AS 1572 hybrid was of 10.705 Mg ha&minus;1 with a N dose of 342 kg ha&minus;1, whereas the AG 9030 hybrid produced a maximum grain yield of 10.089 Mg ha&minus;1 with a dose of 350 kg ha&minus;1 of N. We conclude that the inoculation with A. brasilense increases NUE, maize grain yield, and agronomic characteristic in the AS 1572 hybrid

INGESTIVE BEHAVIOR OF DAIRY COWS GRAZING INTERCROPPED PASTURES IN WARM SEASON

Abstract This research aimed to study the behavior of Holstein lactating cows, during the warm-season on a pasture constituted by elephant grass (Pennisetum purpureum Schum.) and spontaneous growing species intercropped with white clover (Trifolium repens L.) or forage peanut (Arachis pintoi Krap & Greg.). Evaluations were taken during three grazing in December, February, and April. Six cows between the second and fifth lactation month were used for each evaluation. The data were recorded at a 10 min-interval, from 6 P.M. to 6 A.M. and from 8 A.M. to 4 P.M. The grazing time on elephant grass, on species established in space between lines, total grazing (elephant grass and species established in space between lines), rumination and idleness were the behavioral parameters observed. The average of grazing was 3h 48 min and 2h 9 min for pastures intercropped with white clover and forage peanut, respectively, being higher (P <0.05) for the first intercropped forage. The average of the grazing on elephantgrass was 5h 32 min and 6h 27 min for the respective intercropped pastures systems, with no statistical difference between them. The rumination and idleness were similar among the pastures. Keywords: elephant grass; ethology; nutritive value; rotational grazing