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Two experiments were conducted to assess the effect of pre‐grazing heights and proportions of defoliation on morphological and chemical composition of the grazing layer of two warm‐season perennial grasses of contrasting structures (tall tufted grass—elephant grass, Exp. I; small size stoloniferous grass—kikuyu grass, Exp. II) under intermittent stocking management. The treatments were as follows: Exp. I—factorial arrangement between two pre‐grazing heights (90 and 120 cm) and two proportions of defoliation (removal of 50% or 70% of the initial pre‐grazing heights); Exp. II—four pre‐grazing heights (10, 15, 20 and 25 cm) combined with the same proportion of defoliation (50% of the initial pre‐grazing heights). Forage samples were collected at pre‐grazing heights and clipped into the grazing layer (cutting heights defined by treatments). The following variables were analyzed: (a) forage mass; (b) proportion of leaves, stems, and dead material; (c) crude protein, neutral detergent fiber, and acid detergent fiber contents. In a general way, there were no significant differences in morphological and chemical composition of the grazing layer of treatments with proportions of defoliation of 50%. Although the treatments of 70% (Exp. I) and 10 cm (Exp. II) showed some differences, both targets impaired the grazing process and were considered as unpractical under field situations. It was concluded that forage chemical composition of warm‐season perennial grasses does not change in the upper half of the sward within a range of pre‐grazing heights, provided moderate proportions of defoliation (around 50%) are used.

Um dos problemas que envolvem a formação de pastagens de inverno no Sul do Brasil é a variação na qualidade das sementes de espécies forrageiras disponíveis no comércio, o que resulta na comercialização de sementes de baixa qualidade. Neste sentido, objetivou-se avaliar a qualidade de lotes de sementes de azevém anual (Lolium multiflorum Lam.) comercializadas no Sul de Santa Catarina (Brasil), nas safras 2013, 2014, 2015 e 2016, bem como seus efeitos no estabelecimento inicial em diferentes densidades de semeadura. As sementes coletadas foram oriundas do excedente de coletas oficiais de amostra de sementes, realizada por Fiscal Estadual Agropecuário em estabelecimentos comerciais. A qualidade das sementes foi avaliada como variável resposta por meio da pureza física, teste de germinação e número de sementes de outras espécies. Para avaliação do estabelecimento inicial em diferentes densidades de semeadura foi utilizado um delineamento experimental em blocos completos casualizados, em esquema fatorial, 2 x 4, com quatro repetições. Os tratamentos consistiram na aplicação de diferentes densidades de semeadura de duas cultivares de azevém anual (Barjumbo e BRS Ponteio): 12,5, 25, 50 e 75 kg/ha. Foram avaliados o número e altura de plantas, número de perfilhos por planta e massa seca de forragem. É fundamental a necessidade do controle externo de qualidade, executado pelo Estado, por meio da atividade fiscal, com vistas a garantir aos agricultores acesso a sementes de alta qualidade, o que tende a melhorar o estabelecimento inicial de pastagens de inverno. Em relação ao aumento gradativo da densidade de semeadura, constatou-se ganhos de produtividade em ambas as cultivares, com as sementes do cultivar Barjumbo apresentando melhor desempenho que as sementes do cultivar BRS Ponteio.

Italian ryegrass (Lolium multiflorum Lam) is one of the most cultivated temperate annual forage crop around the world. Despite that, there is little information about the process of stem elongation during its vegetative growth. This information would be useful for grazing management purposes. Thus, the aim of this study was to assess the herbage accumulation and stem elongation rates in annual ryegrass pastures submitted to intermittent stocking. The experimental design used was a completely randomized 2x2 factorial with three replications. The treatments were defined by the combination of two pre-grazing heights (15 and 25cm) associated with two post-grazing heights (4 and 8cm). The herbage accumulation rates were higher in pastures with 25cm pre-grazing associated with post-grazing heights of 8cm. However, leaf production rate was only affected by post-grazing height, with higher values being recorded for stubbles heights of 8cm, regardless of pre-grazing height. Stem elongation rates in annual ryegrass tillers increased rapidly when pastures reached around 18cm, a condition where there was a relatively low competition for light, suggesting that; 1) pre-grazing heights of 18 to 20cm in annual ryegrass could be used as a upper limit for grazing management purposes whether the objective is to minimize stem contribution in accumulated herbage and 2) It seems that stem elongation is as inevitable process (independently of competition for light) and that this could be related to the necessary strength of stems, pseudostems and sheaths to support larger and heavier leaves.

Natural pastures are important ecosystems that both contribute to biodiversity conservation and provide an important source of income, especially for cattle ranchers. While these pastures yield fairly low productivity, they can be improved by increasing soil fertility and introducing species with high productive potentials. In this sense, the purpose of this study was to evaluate the effects of applying limestone and phosphorus, as well as introducing cool-season species with a mixture of species dominated by Schizachyrium tenerum Nees, into a natural pasture in the Catarinense Plateau. The experiment was conducted from January 2010 to December 2013; the treatments consisted of superficial distribution of limestone in proportions of 3.6, 7.2, 11.0, and 14.4 t ha-1, as well as distribution of phosphorus in the form of triple superphosphate in proportions of 35, 70, 105, and 140 kg of P2O5 ha-1. In addition, cool-season species were overseeded. The experiment consisted of a randomized block design with subdivided plots and three replications. Limestone was applied to the main parcel, whereas phosphorus was applied to the subplots. There was no interaction between the levels of limestone and phosphorus. The application of 11.0 t ha-1 of limestone yielded the highest forage production, with 3,932.2 kg of dry matter (DM) ha-1 during the second year. Red clover was the species that best reacted to the additions, with levels of 7.2 and 11.0 t ha-1 over the 4 years. In addition, phosphorus provoked a positive response throughout the experiment. The highest forage production was observed during the second year, with an addition of 140 kg P2O5 ha-1 (4,419.4 kg DM ha-1). Only one-eighth of the recommended amount of limestone (3.6 t ha-1) allowed for the establishment and persistence of the legumes introduced into natural pastures. These additions, associated with increasing levels of phosphorus, yielded linear growth in the production of forage in natural pastures with a mixture of species dominated by Schizachyrium tenerum Nees. As pastagens naturais representam um importante ecossistema, com contribuições tanto para manutenção da biodiversidade quanto para geração de renda aos produtores, principalmente na pecuária de corte. No entanto, os níveis de produtividade destas pastagens são relativamente baixos, e podem ser melhorados com incrementos em fertilidade do solo e introdução de espécies de elevado potencial produtivo. Assim, o objetivo deste estudo foi avaliar os efeitos da aplicação de níveis de calcário e fósforo, bem como da introdução de espécies de inverno em uma pastagem natural com predomínio de Schizachyrium tenerum Nees no Planalto Catarinense. O experimento foi conduzido de janeiro de 2010 a dezembro de 2013, e os tratamentos consistiram na distribuição superficial de calcário nas doses de 3,6; 7,2; 11,0 e 14,4 t ha-1; distribuição de fósforo na forma de superfosfato triplo nas doses de 35; 70; 105 e 140 kg de P2O5 ha-1; e a sobressemeadura de espécies de estação fria. O delineamento experimental foi em blocos ao acaso com parcelas subdivididas e três repetições. Os níveis de calcário foram distribuídos nas parcelas e os de fósforo nas subparcelas. Não houve interação entre os níveis de calcário e fosforo. A aplicação de 11,0 t ha-1 de calcário propocionou a maior produção de forragem, de 3.932,2 kg MS ha-1, no 2º ano. O trevo-vermelho foi a espécie que melhor respondeu ao corretivo, nos níveis de 7,2 a 11,0 t ha-1 durante os 4 anos. O fósforo proporcionou resposta positiva durante todo período experimental. A máxima produção de forragem ocorreu no 2º ano para a dose de 140 kg P2O5 ha-1 (4.419,4 kg MS ha-1). Apenas 1/8 da recomendação de calcário (3,6 t ha-1) permite o estabelecimento e a persistência de leguminosas introduzidas em pastagem natural, dose esta que associada à níveis crescentes de fosforo proporcionam aumentos lineares na produção de forragem em pastagem natural com predomínio de Schizachyrium tenerum Nees.

The objective of this study was to assess forage production in a natural grassland by applying different doses of limestone and phosphorus, and the influence of these applications on soil profile. The treatments consisted of the application of limestone doses of 0.0, 7.2, and 14.4 t ha-1 and phosphorus doses of 0,35, 70, and 140 kg of P2O5 ha-1 on the soil surface. The experiment was conducted in a randomized complete block design with split-plots and three replications. The limestone doses were distributed in the main plot and applied only at the beginning of the experiment, whereas the phosphorus doses were distributed in the subplots with subsequent annual maintenance applications. Was used a ruler (cm) for monitoring the growth of pastures and, when grasses reached an average height of 20 cm, forage samples were collected in each subplot and botanical and morphological components were separated and dried until a constant weight was achieved. In the third and fourth assessment years, soil samples were collected in the 0-5, 5-10, 10-15, and 15-20-cm layers to evaluate the influence of treatments on the chemical properties of the soil. The variables analyzed were related to the production of several components, including fodder, native grasses, leguminous plants, unwanted plants, and dead material, in addition to soil properties such as pH, exchangeable aluminum concentration, and base saturation. There was no interaction between the limestone and phosphorus treatments. The effect of limestone doses on forage production was assessed in the third year, and, in the following year, the intermediate dose of limestone (7.2 t ha-1) produced the highest yield (2,316.1 kg of dry matter [DM] of forage ha-1). The increase in phosphorus doses increased forage production in the second year, and reached yields of up to 2,232 Kg DM ha-1 in the fourth year. In summary, the production of natural pastures was enhanced by the application of 25% of the recommended dose of limestone (7.2 t ha-1), and by the application of 50% of the recommended dose of phosphorus (70 kg P2O5 ha-1). The increase in limestone doses directly affected the chemical properties of the soil by decreasing acidity and exchangeable aluminum, and increasing base saturation, even in deeper layers (0-20 cm). The increase in phosphorus doses did not increase the mobility of this nutrient in the deeper layers of the soil (10-20 cm), and the effects were restricted to a depth of up to 10 cm.