Dr Pieter A Swanepoel Pengarang

Phytomass estimation using eMODIS NDVI and ground data in arid rangelands of Morocco Hamid Mahyou1*, Bernard Tychon2, Marie Lang2 and Riad Balaghi3 ABSTRACT The assessment of rangeland productivity in semi-extensively grazed arid rangelands is a prerequisite for livestock management in relation to sustainable use of pastoral resources. The objective of this study was to assess rangeland productivity based on normalised difference vegetation index (NDVI) images. Data on phytomass were measured on 61 field samples in arid rangelands of Morocco, covering various rangeland categories during autumn (November) and spring (April), i.e. when phytomass is at low and high levels, respectively, for two consecutive years (2008 and 2009). Dekadal EROS Moderate Resolution Imaging Spectroradiometer (eMODIS) NDVI data were linearly regressed to field measurements for these four periods. Results show that phytomass values were correlated with NDVI during spring, with R  2 and RMSE values of 0.82 and 0.3 t ha−1, respectively. This study indicates there is a high potential for operational use of remotely sensed data to estimate rangeland phytomass of semi-extensively grazed rangelands. Keywords: arid pasture, biomass, Morocco, regression model, vegetation index Effect of stocking density on vegetation and animal performance within the semi-arid shrublands of the Karoo, South Africa Christiaan J Harmse* and Hannes J Gerber ABSTRACT As the primary land use in the Karoo, extensive small-stock farming contributes significantly towards the agricultural economy of the region. However, the sustainability of this practice has been questioned for many years. This led to the establishment of a long-term stocking-density trial in 1988 at the Carnarvon Research Station. The trial was designed on a three-camp rotational grazing system under four stocking densities (8, 7, 5.5 and 4 ha SSU–1). Following continuous treatment over 28 years, the results from a once-off assessment in February 2016 portrayed no significant differences between treatments with regard to plant height, cover, species diversity, ecological and grazing index scores. Animal production varied among treatments where the mean production per hectare was found to be the highest under the high stocking-density treatment. Due to the absence of historical data, the results from this study are not conclusive with regards to changes in the vegetation dynamics over time and therefore does not lend itself to making conclusions concerning stocking densities. It can, however, be concluded that the vegetation of the Western Upper Karoo is remarkably resilient to the perceived higher stocking densities set at the time, on condition that an appropriate grazing management strategy is applied. Keywords: grazing management, stocking density, three-camp system, veld condition, weight gain The effect of Holistic Planned Grazing™ on African rangelands: a case study from Zimbabwe Mike Peel1,2,3* and Marc Stalmans4 ABSTRACT Holistic Planned Grazing™ (HPG) is purported to have positive long-term effects on rangelands, enhancing ecosystem services. Given comparable environmental templates, but different management regimes, vegetation monitoring and landscape function analysis showed the Africa Center for Holistic Management (ACHM) at Dimbangombe had a significantly higher rangeland condition (composition, cover, standing crop and soil health) than adjacent Sizinda (SCR) and Monde (MCR) communal rangelands. Overall grazer density on ACHM is 42% higher than that of SCR (no data for MCR). Finer-scale satellite collar data for ACHM yielded a calculated stocking rate of 0,55 LSU ha−1 y−1 or 24 590 kg km−2, which constitutes high-density grazing. An energy flow estimate shows that the grazing resource would, on average, not be limiting for livestock on ACHM but limiting on SCR. HPG may include an element where kraals are inserted into degraded rangelands for a short period. Overall, ACHM shows stable perennial composition with smaller tufts significantly closer together. A similar result was visible in SCR where maize yields were visibly higher on kraaled areas than on adjacent untreated fields. HPG yields positive long-term effects on ecosystem services (soils and vegetation) and points to the HPG approach enhancing the sustainability of livestock and wildlife in this environment. Keywords: basalt, kraal, landscape function, perennial grasses, stocking density Land-use and land-cover changes and their drivers in rangeland-dependent pastoral communities in the southern Afar Region of Ethiopia Muluken Mekuyie1* , Andries Jordaan1 and Yoseph Melka2 ABSTRACT The present study was conducted in the southern Afar Region in Ethiopia to analyse the trends of land-use and land-cover changes and their drivers in the period 1985 to 2015 using remote sensing, field observation, focus group discussions and semi-structured interviews. A substantial loss of grassland cover (64.5%), moderate decline of cultivated land (24%) and a considerable increase in bush and shrub land cover (114.3%) occurred between 1985 and 2015. Consequently, pastoralist’s access to rangeland resources and farmlands was highly restricted, thus putting the pastoral production system under increasing threat. A 13.3% decline of bare land was also observed during the same period. The results further indicated that policy, climate change, and variability, biotic factors including population growth, overgrazing, Prosopis juliflora seed dispersal via livestock’s fecal droppings and seed germination potential of P. juliflora under moisture stress were the most important drivers of land-use and land-cover changes. Therefore, policy and strategies should be developed to control P. juliflora and give pastoralists full rights to their grazing land. Furthermore, there should be a strategy to strengthen the customary institution for effective management of rangeland resources. Keywords: grassland, land cover, land use, pastoralists, Prosopis Temperature control of the distributional range of five C3 grass species in the uKhahlamba-Drakensberg Park, KwaZulu-Natal, South Africa Luke K Bentley* and Tim G O’Connor ABSTRACT Global climate change is expected to influence the distribution of global biodiversity. C4 and C3 perennial grasses co-occur in the fire-prone KwaZulu-Natal uKhahlamba-Drakensberg grasslands, with C3 grass species occurring at cooler locations in the mountain range and C4 grass species at warmer locations. If a warming climate is expected to cause a contraction in the ranges of C3 grasses, evidence of temperature controlling current distributions is required. This study modelled the distribution of five C3 grass species, namely Tenaxia stricta, Tenaxia disticha, Festuca costata, Merxmuellera drakensbergensis and Merxmuellera stereophylla, to temperature-related surrogate variables using presence–absence data collected across the environmental heterogeneity of the mountain range. Distributions of each species, and of all species combined, were modelled using generalised additive models. These temperature-related variables accounted for the distribution of all five species, least so for F. costata. Four species could therefore contract in range in response to climate change, whereas F. costata is least likely to have a range contraction directly related to a warming climate and could experience a range expansion owing to the fertilising effect of increased [CO2]. Keywords: climate change, grassland, modelling, montane Effects of urea addition on the fermentation of sorghum (Sorghum bicolor) silage Ana Paula Maia dos Santos1, Edson Mauro Santos1 , Juliana Silva de Oliveira1, Ossival Lolato Ribeiro2, Alexandre Fernandes Perazzo3* , Ricardo Martins Araújo Pinho1 , Alberto Jeferson da Silva Macêdo1 and Gildenia Araújo Pereira1 ABSTRACT This study was conducted to evaluate the effects of urea addition on fermentation characteristics, losses and chemical composition of silage of sorghum (Sorghum bicolor) ‘BRS Ponta Negra’. The sorghum plant was chopped and treated with different levels of urea (0.1756, 0.3512, 0.7024 and 1.4048 g per 10 kg fresh forage for the respective proportions of 0.5%, 1.0%, 2.0% and 4.0% of forage (dry matter [DM] basis), and packed into quintuplicate experimental silos to determine its effects on fermentation, losses and chemical composition of sorghum silages. Addition of urea increased lactic acid bacteria up to the level of 60 g kg−1 (DM basis). Compared with control silage, the addition of urea (p < 0.05) reduced DM losses. Urea-treated silages linearly increased (p < 0.05) the ammoniacal nitrogen and crude protein contents, and linearly reduced (p < 0.05) the ethanol content. The pH in urea-treated silages indicated better preservation of substrates obtained from fermentation. The intermediate level of 2.0% urea additive can be used to improve fermentation, reducing losses in sorghum silage without compromising lactic acid production. However, the addition of 0.5% and 1.0% urea to sorghum silage is sufficient to improve aerobic stability. Keywords: chemical additive, fermentation profile, forage preservation Oat silage for grazing dairy cows in small-scale dairy systems in the highlands of central Mexico Victor Andrés Burbano-Muñoz1, Felipe López-González1 , Julieta Gertrudis Estrada-Flores1 , Pedro Alan SainzSánchez2 and Carlos Manuel Arriaga-Jordán1* ABSTRACT The objective was to evaluate the provision of oat silage (Avena sativa) to supplement grazing dairy cows on pastures of perennial ryegrass (Lolium perenne), festulolium (Lolium multiflorum × Festuca pratense) and white clover (Trifolium repens) during the dry season when pasture growth is limited. The experimental design was a 3 × 3 Latin square replicated three times, with nine milking Holstein cows (mean live weight 496.2 ± 33.6 kg and daily milk yield 14.8 ± 2.8 kg cow−1) under on-farm participatory rural research. Experimental periods were 14 d. Simulated grazing samples of pasture herbage were analysed for chemical composition, sward height recorded and net herbage accumulation determined from exclusion cages. Treatments were the inclusion of oat silage at T0 = 0 kg DM cow−1 d−1 of oat silage, T3 = 3 kg DM cow−1 d−1 of oat silage, and T6 = 6 kg DM cow−1 d−1 of oat silage, plus 5.0 kg fresh weight commercial concentrate and 9 h of continuous grazing. Animal variables were milk yield and composition, live weight and body condition score. Feeding costs were calculated. Mean milk yield was 18.9 ± 0.27 kg cow−1 d−1 with no differences in animal variables (p > 0.05), but feeding costs per kilogram milk increased 25% for T3 and 50% for T6. Oat silage supplementation is only viable under difficult grazing conditions. Keywords: climate change, feeding costs, forage supplementation, festulolium, ryegrass