Tropical Grasslands

Tropical grasses sometimes contain oxalate in suffi cient concentrations to induce calcium defi -ciency and toxicity in grazing animals. This pot study was undertaken to investigate the effects of clipping interval and N fertilisation on the oxalate concentrations in napier grass. Plants were treated with 2 rates (5 and 30 g/m 2) of N ferti-liser (as urea) and harvested at 3 clipping inter-vals (2, 4 and 8 weeks). At all clipping intervals, both forage dry matter yield and crude protein concentration in the forage were greater (P<0.05) with the higher N fertiliser rate than with the lower rate. Clipping increased oxalate concen-tration (P<0.05), and oxalate levels declined as the harvest interval increased. Across all clip-ping regimes, concentrations of soluble (15.2 vs 14.9 g/kg DM), insoluble (11.1 vs 12.0 g/kg DM) and total (26.3 vs 26.8 g/kg DM) oxalates in the plant tissues were not affected signifi -cantly (P>0.05) by level of N fertiliser applied. These results sugg...

Fragmentation had been one of the major threats to grassland ecosystems of India. Studies find that grassland ecosystems across the country have been already displaying negative effects of loss of continuity and fragmentation. The present discussion note explores the possibilities of establishment of pastoralist-wildlife corridors over the grasslands of India for unrestricted movement of the pastoralists-livestock and wildlife and unhindered functions and ecosystem services of the grassland ecosystems in India.

Results of screening and evaluation trials of forage legumes for rangeland improvement in Zimbabwe from 1980-2005 are reviewed. Attributes used for selecting legumes and rangeland manage- ment trends are highlighted. Stylosanthes spp., Chamaecrista rotundifolia, Macrotyloma axillare, Desmodium uncinatum, Desmodium intortum, Macroptilium atropurpureum, Lotononis bainesii, Arachis pintoi, Aeschynomene americana and Neonotonia wightii, among others, were rec- ommended for rangeland improvement under the different soil, moisture and grazing man- agement conditions in Zimbabwe. Since 1980, evaluation programs have been aimed at inves- tigating and developing low-input legume-based forage production technologies for the resource- poor farmers in different agro-ecological zones of Zimbabwe. Awareness and adoption of these promising legumes by smallholder and communal farmers were identified as major challenges for rangeland improvement in Zimbabwe. Major constraints in adoption of legume p...

The taxonomy, morphology, and geographic distributions of Habenaria crucifera and related species in section Nudae were investigated. Habenaria galeandriformis and H. montiswilhelminae are included in the affinity of H. crucifera and four new taxa are described: H. cardiostigmatica, H. crucifera var. brevidactyla, H. guaraensis, and H. spanophytica. These species form a subgroup within section Nudae, characterized by linear grass-like leaves that are appressed to the stem; green flowers; simple or discretely bipartite petals; a tripartite lip; a rostellum midlobe completely placed between the two anther loci; stigma lobes that are closely parallel; and a separated hemipollinarium. This group of species ranges from the Guianas to the state of Rio Grande do Sul in southern Brazil, but is concentrated in the cerrado of central Brazil. Diagnostic characters, illustrations, descriptions and notes on the habitat, distribution, phenology, and conservation status are presented for all species here recognized. A taxonomia, morfologia e distribuição geográfica de Habenaria crucifera e espécies relacionada na seção Nudae foi investigada. Habenaria galeandriformis e H. montiswilhelminae são incluídas na afinidade de H. crucifera e quatro táxons novos são descritos: H. cardiostigmatica, H. crucifera var. brevidactyla, H. guaraensis e H. spanophytica. Essas espécies formam um subgrupo da seção Nudae caracterizado pelas folhas graminóides, lineares, apressas ao caule, flores verdes, pétala simples ou discretamente bipartida, labelo tripartido, lobo mediano do rostelo completamente compreendido entre os lóculos da antera, lobos do estigma próximos, paralelos, e hemipolinários separados. A distribuição das espécies estende-se das Guianas até o estado do Rio Grande do Sul no sul do Brasil, mas concentra-se no cerrado do Brasil central. Caracteres diagnósticos, ilustrações, descrição e comentários sobre o habitat, distribuição, fenologia e status de conservação são apresentados para cada espécie.

This study was carried out to assess the effect of season, elevation, bush encroachment and location on the condition of the rangelands in Borana. A survey was conducted during the long and short rainy seasons of 1998 at a time when most grass species were at full fl owering stage on a government ranch and 6 communal grazing areas. Each of the study areas covered 3 elevation zones: low (1250–1500 m), medium (1500–1650 m) and high (1650–2000 m). The assessment of range condition was based on the botanical composition of the herbaceous layer, basal cover, litter cover, relative number of seedlings, size distribution of dominant grasses and soil condition. The overall results showed that season, bush encroachment and location of the rangeland had signifi cant effects on condition of the rangelands. Overall range condition scores were higher during the long rainy season than in the short rainy season and in range sites that were not affected by bush encroachment. Moreover, the total ran...

Thirty-two accessions of the Caulorrhizae sec-tion of the genus Arachis were evaluated at 2 dif-ferent sites in the Brazilian Cerrados, in terms of flowering period and intensity, seed yield and dis-tribution in the soil profile. Flowering occurred between October and May with the accessions dif-fering in the distribution, intensity and period of flowering. They exhibited a cyclic flowering pat-tern, with various peaks of production of flowers. Differences in maximum flowering intensity were also observed among sites. The average seed yield 18 months after planting was 948 kg/ha at Location 1 (lowland area) and 327 kg/ha at Loca-tion 2 (well drained area). The accessions exhib-ited great variability for this trait, with an average broad-sense heritability (H²) value of 0.73. While 99% of the seeds were concentrated in the first 6 cm of the soil profile, seeds were recovered to 9 cm depth at Location 1 and to 12 cm at Loca-tion 2. Genetic variability was also observed for this trait.

Availability of adequate good quality fodder is a major constraint to animal production in Zimbabwe, especially in the smallholder dairy sector. Strategies to alleviate this problem have included the use of commercial protein sources, and herbaceous and tree legumes as supplements to crop residues and native pasture, the resources that form the major feed base. During the 1994–95 cropping season, the International Centre for Research in Agroforestry (ICRAF) in Zimbabwe introduced leguminous fodder trees to smallholder dairy farmers in the Chikwaka Communal Area of Zimbabwe. Subsequently, studies were carried out to determine the level of integration of fodder trees into feeding systems in this farming sector and to identify the opportunities for and constraints to the use of this feed resource. Formal and informal surveys were conducted to examine farmers’ views on the agronomic, nutritional and economic performance of the treebased fodder bank technology. Five years after the intro...

Agriculture is responsible for a significant proportion of total anthropogenic greenhouse gas emissions (perhaps 18% globally), and therefore has the potential to contribute to efforts to reduce emissions as a means of minimising the risk of dangerous climate change. The largest contributions to emissions are attributed to ruminant methane production and nitrous oxide from animal waste and fertilised soils. Further, livestock, including ruminants, are an important component of global and Australian food production and there is a growing demand for animal protein sources. At the same time as governments and the community strengthen objectives to reduce greenhouse gas emissions, there are growing concerns about global food security. This paper provides an overview of a number of options for reducing methane and nitrous oxide emissions from ruminant production systems in Australia, while maintaining productivity to contribute to both objectives. Options include strategies for feed modi...

This study was carried out to assess the effect of season, elevation, bush encroachment and location on the condition of the rangelands in Borana. A survey was conducted during the long and short rainy seasons of 1998 at a time when most grass species were at full fl owering stage on a govern- ment ranch and 6 communal grazing areas. Each of the study areas covered 3 elevation zones: low (1250-1500 m), medium (1500-1650 m) and high (1650-2000 m). The assessment of range condition was based on the botanical composition of the herbaceous layer, basal cover, litter cover, relative number of seedlings, size distribution of dominant grasses and soil condition. The overall results showed that season, bush encroachment and location of the rangeland had signifi cant effects on condition of the rangelands. Overall range condition scores were higher during the long rainy season than in the short rainy season and in range sites that were not affected by bush encroachment. Moreover, the total r...