Sustainable development of semi-arid grassland utilsation through optimised management of stock densities, recovery periods and carring capacity of organic cattle and sheep farming on the example of Springbockvley, Namibia
Grazing is still the most important utilisation of the vast semi-arid savannas of Afrika. This areas are endagered due to climate change and not sustainable herd management (degradation and desertification). With measures of organic farming and holostic management we try to increase the natural biomass production and therefore the production of meat in kg per hectare and year. This will result in better profitability and performance of grassland farming.
Livestock farming in the vast grazing areas in Namibia partly shows severe management deficiencies which results in desertification and degradation. Livestock is kept in fenced pastures on ranches, herded on communal farmland, or kept as free roaming or herded livestock at low stocking rates (10-20 ha / LU). A major problem for grassland productivity in savanna rangelands is the absence of recovery periods. Insufficient recovery periods lead to reduced productivity.
Inproved grazing systems with high stock densities do impact through trampling, defoliation of plants, and excretion, influence water and nutrient flux processes and parameters, and thus overall grassland productivity. This does result in more biomass and last but not least in higher meat productivity or less risk in the case of drought.
Questions for the research are:
Different stocking densities and stocking rates of a 800 head cattle herd and 3,500 head sheep flock on the 9,500 ha rangeland farm Springbockvley in Namibian Organic will be taken as starting point to assess and develop sustainable stock densities and stocking rates on grassland in Namibia. The farm is managed according to the Holistic Management (HM) principles since 1990. All 3 herds will follow the „red grazing line“ on the farm and will give recovery/resting periods between 60 and 100 days. That means, that every herd/flock will have grazed every paddock approximately 1,3 times a year. The experiment will be carried out for 4 years (2014 – 2018).
For the project two variations will be integrated into the normal (control) grazing management:?
These variations will be compared with the current system of stock density and stocking rate. For these experiments, 4 replications have been selected on the farm. The goal of the research is to prove if these changes can be measured scientifically with several methodologies.
A) Grazing management for experiments
The variation of the herd management will be done while the routine grazing modus, following the „red line“. There will be no fixing of the date, when the herds enter the paddock. The herds will enter each paddock in compliance with the grazing plan designed as per description above. The fodder availability expressed in grazing days per ha will be assessed in May of each year. The selected paddocks will be managed according to the grazing plan, and this will be assessed. The „red line“ has been modified so that the herds/flocks will always graze two normal paddocks (managed according to the current grazing regime) before they enter a treatment paddock (increased density or double stocking rate). This is deemed necessary as an adaptation period for the animals before entering treatment. The second of the normal paddocks between two treatments serves as control (cf. Table and map above).
B) Livestock assessment
C) Vegetation assessment
The main proof of the herd management will be on the assessment of the vegetation. Because it is not clear, which methodology of biomass measurements can be used, a tool test (methodology assessment) has been included in the study. Five different methodologies have been choosen for comparison:
Platemeter test: Transect walk with a platemeter on all treatment and control paddocks. ?How and when to be done: every May from corner to the opposite (diagonal) corner (between 1 and 2 km), every 2nd step one measurement. The transect will be done every year at the same time (May) and the interannual comparison of the „average biomass hight“ will be the indication of growth and biomass. ?
The comparison of these 5 very different vegetation tests is assumed to allow answers about the best, cheapest and most usuable measure (also for farmers) to assess the vegetation coverage, biomass and grazing days estimations
The meat production on Springbockvley was assessed by farm records from 1994 till 2012, the last year before converting towards organic farming and the novel grazing management system. The rainfall was uncertain and between 61 mm (1995) and 680 mm per year (2011), surprisingly with a slight increasing trend. The stocking rate and the meat production do follow the annual rainfall performance (Figure 4). The stocking rate varied between 17 (1995) and 43 kg live weight (2012) per hectare, the meat production (live weight) per hectare between 5.3 (1995) and 15.2 kg (2013).
The average number of different plant species on the different experimental grazing was assessed on 2,500 sqm plots before and after the three herds of cow herd, oxen and sheep have used the plots (Table 3).The total average number of species found in sampling plots before grazing events is higher than after grazing events. This applies to all grazing treatments, double stocking rate, high density and normal grazing respectively.
12.2013 - 12.2017
Project status: ongoing