Productivity of Winter and Spring Native Improved Vegetation under Different Grazing Stocking Rates on Basaltic Soil

Improved grassland with Lotus corniculatus, Trifolium repens and annual phosphorus fertilization, was evaluated during winter and spring for five consecutive years under grazing at three different stocking rates on medium basaltic soil. Specific contribution of Lotus and Trifolium reached 67% of grassland community in the first year. Stipa setigera and Poa lanigera increased their contribution from 0.8 to 17% in the fourth year of grazing experiment. Highest average value of crude protein was 19% during the second year and was related to legumes contribution. Forage availability was always up to 1.5 ton MS/ha at the three stocking treatments. Average daily gain was 770, 720 and 675 g/steer/day for 1.4, 1.9 and 2.3 steers/ha during the evaluated period

Utilization of forage legumes in pastoral systems: state of art in Uruguay.

Introduction:Improved pastures, integrated by forage legumes, are the primary base of agriculture and cattle rearing in Uruguay. The growing demand for cattle products requires higher cattle productivity, which is at the present time limited by the yield and quality of the natural pastures, mainly based in summer grasses. Perennial sown pastures in Uruguay have had a slow but sustained increment in area in the last five decades, from 17.000 has in 1950 to 1.287.000 has in 2003, representing 7% of total pastoral area (DIEA, 2004). In spite of agricultural policies that promoted the sowing of introduced legumes in the sixties, natural grasslands over sown with legumes represents 5% of the total area at the present time (0,7 million has; DIEA, 2004). Diverse factors have influence on the slow adoption of sown pastures, among others the cost of establishment, the uncertainty of the physical result due to poor persistence of the introduced legumes, establishment difficulties, the need of careful defoliation management that require some legumes that produce bloat

Prevention of natural grassland invasion by Eragrostis plana Nees using ecological management practices

The objective of this research was to evaluate the effects of different types of disturbance on the ability of the natural grassland to avoid the invasion of Eragrostis plana Nees (South African lovegrass). The experiment was carried out in Dom Pedrito, Rio Grande do Sul, Brazil, in an area free of South African lovegrass, from Feb. 2004 to Apr. 2007. The treatments were: 1) grassland management regimes: exclusion; low grazing intensity (rotational grazing), ±10 cm; and high grazing intensity (continuous grazing), ±5 cm; 2) initial levels of soil disturbance: high grassland, ±10 cm; low grassland, ±5 cm height; and low grassland with scarified soil; 3) fertilization regimes: without fertilization; phosphorus; and nitrogen. The experimental design was a split-split-plot type in complete blocks, with three replicates. Three winter cultivated species - Trefoil repens L., Lotus corniculatus L., Lolium multiflorum Lam. and South African lovegrass -were sown in 54 split-splitplots (split-plots: low grassland, and low grassland with scarified soil). The other 27 split-split-plots (split-plots: high grassland) were sown only with South African lovegrass. The grassland height, plant number of South African lovegrass, grassland dry mass and photosynthetic active radiation intercepted (FARint) at the soil level were recorded. The fertilization regimes did not influence the South African lovegrass plant number. The initial levels of soil disturbance and grassland management regimes influenced the invasion of South African lovegrass. The invasion was favored by the lower grassland height and lower forage mass, higher intensity of the soil disturbance, and higher FARint due to the continuous grazing. On the contrary, higher grassland height, higher forage mass, lower soil disturbance and lower FARint, associated with rotational grazing or exclusion, showed higher potential to control the invasion of South African lovegrass in the natural grassland

Desempenho de leguminosas nativas (Adesmia) e exóticas (Lotus, Trifolium), em função do estádio fenológico no primeiro corte Performance of native (Adesmia) and exotic (Lotus, Trifolium) legumes as for the phenological stage on first-cutting

Este trabalho foi desenvolvido com o objetivo de analisar aspectos fenológicos e produtivos de leguminosas nativas (Adesmia latifolia, A. tristis) e exóticas (Lotus corniculatus, L. uliginosus, Trifolium repens), em função do estádio fenológico no primeiro corte: vegetativo (CEV) e florescimento (CEF). As plantas foram estabelecidas em monocultura, no campo, e avaliadas entre maio/2000 e setembro/2001, em Passo Fundo, Rio Grande do Sul. Após o primeiro corte, as plantas foram desfolhadas em intervalos de 45 dias. Foram realizadas nove desfolhações no manejo CEV e sete no CEF. O estádio fenológico no primeiro corte influenciou a produção de massa seca (MS) de T. repens (CEV= 9.000 kg/ha de MS, CEF = 7.000 kg/ha de MS) e A. tristis (CEV = 4.000 kg/ha de MS, CEF = 8.000 kg/ha de MS). O L. corniculatus produziu cerca de 15.000 kg/ha de MS e A. latifolia, de 2.000 a 3.000 kg/ha de MS, independentemente do manejo. O L. uliginosus não floresceu, produzindo 7.000 kg/ha de MS no manejo CEV. As espécies nativas mostraram baixa persistência, com morte de plantas (A. tristis) e estolões (A. latifolia) no final da estação de crescimento. A maior produção de T. repens foi na primavera e a das espécies de Lotus, no verão.<br>This work had the objective to evaluate phenological and productive aspects of native (Adesmia latifolia, A. tristis) and exotics legumes (Lotus corniculatus, L. uliginosus, Trifolium repens) as for the phenological stage on first-cutting: vegetative (CEV) and flowering (CEF). The plants were established as monoculture in the field and evaluated between May/2000 and September/2001, in Passo Fundo, Rio Grande do Sul. After the first cutting the plants were defoliated in 45 days intervals. There were nine cuttings in CEV-management and seven in the CEF-management. The phenological stage on first-cutting modified significantly (P<0,05) the dry matter (DM) production of T. repens (CEV = 9.000 kg/ha of DM, CEF = 7.000 kg/ha of DM) and A. tristis (CEV = 4.000 kg/ha of DM, CEF = 8.000 kg/ha of DM). L. corniculatus produced about 15.000 kg/ha of DM and A. latifolia, 2.000 to 3.000 kg/ha of DM, regardless the management. L. uliginosus did not flowered, producing 7.000 kg/ha of DM in the CEV-management. The native legumes showed poor persistence with death of the plants (A. tristis) and stolons (A. latifolia) at the end of the growing season. The highest production of the T. repens was in the spring and for the Lotus species, in the summer

Semeadura direta de forrageiras de estação fria em campo natural submetido à aplicação de herbicidas: II. Composição botânica No-till seeding of cold season forage on native pasture under herbicides application: II. Botanical composition

A semeadura direta de espécies forrageiras de estação fria permite reduzir a marcada estacionalidade da sua produção em campos naturais. Durante quatro anos, conduziu-se um experimento de aplicação de herbicidas sobre campo nativo, em um solo Argissolo Vermelho-Amarelo, de textura arenosa do norte do Uruguai visando introduzir forrageiras de estação fria e estudar o impacto dos herbicidas na composição botânica de espécies estivais. Foram testadas doses de herbicidas (glifosate 1L ha-1, glifosate 4L ha-1, paraquat 3L ha-1 e testemunha), como tratamento principal, aplicadas no ano 1994, em um delineamento blocos ao acaso. A repetição ou não das mesmas doses no ano 1995 constituiu a subparcela e a aplicação ou não das mesmas doses no ano de 1996 constituiu a sub-subparcela. No levantamento de espécies da vegetação existentes no outono de 1998, observou-se que o maior distúrbio sobre a composição botânica do campo nativo foi provocado com a aplicação continuada da dose de 4L ha-1 de glifosate, onde foram identificadas seis espécies. No levantamento de espécies existentes no tratamento testemunha, no outono, foram identificadas onze espécies, sendo que as espécies Andropogon lateralis, Paspalum notatum, Conyza bonariensis, Eryngium horridum, Desmodium incanum, Cyperus sp. e Digitaria sp. constituiram 90% da composição botânica. Com a aplicação de herbicida, ocorreu uma substituição de espécies perenes por anuais.<br>No-till seeding of winter species may reduce seasonal fluctuations of forage production of natural grasslands. An experiment of herbicide application on native grasses was conducted for four years, on a fine-loamy, mixed Mollic Hapludalf in northern of Uruguay to introduce winter forage and study the impact of herbicide on botanical composition of grass field. The experimental design was split-splitplot with three randomized blocks, with types and dosis of herbicides (gliphosate 1L ha-1, gliphosate 4L ha-1, paraquat 3L ha-1 and a check without herbicides) as main treatments, applied in 1994. The application or not of the same treatments in 1995 constituted the splitplots, and their reapplication or not in 1996 constituted the split-splitplots. The botanical composition in the fall of 1998 showed that there were only six species in the treatment with the higher gliphosate rate applied every year, meanwhile in the check there were eleven species. Andropogon lateralis, Paspalum notatum, Conyza bonariensis, Eryngium horridum, Desmodium incanum, Cyperus sp. and Digitaria sp. were responsible for 90% of the total botanical composition of the grassland. There was a substitution of annual for perennial species due to the most agressive herbicide treatment