Need for rangeland improvement Sei tichifanira kufunga nezvemafuro edu?3 Deterioration evidenced by: 1. Changes in grass species composition – invader/increaser species (Sporobolus, Aristida) 2. Proliferation of undesirable/invasive plants e.g., forbs 3. Bush encroachment and tree recruitment – we have to arrest plant succession at the grass stage 4. Soil erosion 5. Accumulation of top hamper and moribund material Ultimately low animal productivity (growth
Changes in species composition Huswa huri kushanduka mumafuro4
Kuisa fetiraiza mumafuro12 Types: Ammonium Nitrate (AN), single supers How– every 4 years (kamwe chete mumakore mana) Benefits/Zvakanakira kuisa fetiraiza increased forage yields and quality (goho rinokwirira) higher stocking rates (tinochengeta mombe dzakawanda) Increased animal productivity Reduction of undesirable plants
Kuisa fetiraiza mumafuro13 Disadvantages/Matambudziko Poor response to fertiliser application (mutsauko wacho mudiki mumafuro atagara tiinawo) Rangelands areas have limited land use capability - water-logged vlei soils; shallow soils, steep slopes, rockiness, etc. (nzvimbo dzine mafuro hadzirimike uye dzinonetsa kuisa fetiraiza) High cost (fetiraiza inodhura) Shortages (fatiraiza yacho haiwanikwi) Generally not economic on native pasture in Zimbabwe Not recommended (nzira iyi hatiikurudzire)
Control of undesirable plants Kubvisa miti nehufuro14 husingadiwe These are plants that are: Notreadily eaten by animals Less productive or reduce veld productivity Reduce amount of utilisable herbage Conflict with veld management Undesirable plants: Invaderand invasive species Poisonous species E.g., Lantana camara, Dichapetalum cymosum, Urginea sanguinea, Solanum incanum (nhundurwa), etc. Bushes and trees
Control of undesirable plants Kubvisa miti nehufuro15 husingadiwe
Control of undesirable plants Kubvisa miti nehufuro16 husingadiwe Bushes and trees Removal by stumping, ring barking, or by mechanical means like bulldozers, brush-cutters and motorized saws. chemicals (arboricides eg picloran, bromacil etc) use of prescribed hot fires Bushes and other undesirable plants practicinggood veld management Prescribed hot burns (fire).
Range rehabilitation17 (kugadzirisa zvakakanganisika) Degraded and eroded areas Methods of rehabilitation Thatching and brush laying Pitting Stone lines Planting grass lines- e.g., vetiver grass (Vetiveria zizanoides), elephant grass (Pennisetum purpurem) and paspalum (Paspalum notatum). Often a combination of techniques is needed for most effective and rapid rehabilitation. Rehabilitation is an attractive option on a small- scale but almost not feasible on a large scale.
Rangeland Reinforcement (kuwedzera humwe huswa mumafuro aripo)18 Veld reinforcement entails the sowing of improved grass and legume species into native pasture This is the most feasible means by which rangeland productivity can be raised above natural levels in this country. Most effective when legume content is >30% in veld Legumes planted into the top-land veld and grasses into vleis.
Reinforcement with legumes19 Fix nitrogen (80-100kg N/ha) Come away earlier in the season Legumes have higher feeding value in late summer and winter (extend grazing season) Results in Zimbabwe: Grazing capacity increased by up to 20% Production increased by over 50% At Grasslands, steers on improved veld gained 40kg/year more than those on unimproved veld
Reinforcement with improved grasses21 In vleis/wetter areas we find that often improved grasses are more suitable than legumes. The following improved grass species are suitable for veld reinforcement in vleis in Zimbabwe: Acroceras macrum (Nile grass) Brachiaria arrecta (tanner grass) Paspalum urvillei (vasey grass) Panicum repens (torpedo grass) Paspalum dilatatum (dallis grass)
Rangeland reinforcement22 High rainfall areas – Desmodium spp (heavier soils) Stylosanthes spp (lighter soils) Low rainfall areas – siratro, cassia and Archer The benefits of rangeland improvement include: greaterrange productivity increased forage quantity and quality improved animal performance and reduced winter protein supplementation. Reduced fattening costs due to higher induction masses This strategy for veld improvement is highly
Replacement with sown pastures (kuisa mafuro matsva)23 Native grassland is ploughed out and completely replaced with highly productive pasture grasses Dryland temporary pastures – short term leys, they form part of the cropping system. rotation with tobacco for rootknot nematode tolerance - Katambora Rhodes grass (Chloris gayana) Also: forage sorghum, millets, velvet bean, lablab, etc. Need little fertilisation as they rely on residual
Replacement with sown pastures (kuisa mafuro matsva)24 Permanent dryland pastures – star grass, kikuyu, napier grass, etc. species should respond well to nitrogen fertilisation and withstand severe defoliation/grazing pressure. Irrigated pastures veryexpensive form of production mostly used for finishing cattle and for dairying. Ryegrass, Lucerne (alfalfa) and clovers are the most suitable species for irrigated pastures.
KUCHENGETEDZA MAFURO (Sound range and grazing management25 principles) Principles to be discussed 1. Stocking rates 2. Period of stay 3. Resting 4. Top hamper removal 5. Grazing systems 6. Use of fire (Prescribed burning)
Stocking rates26 Stocking rate is the number of hectares allocated by the farmer for each livestock unit (i.e., a beast weighing 500kg) It is the most important factor affecting productivity and stability of the veld. Correct stocking rates are important for the perpetuation of the range (condition and productivity), well-being of the livestock and the economic stability of livestock operation. Overstocking results in overgrazing. Under grazing leads to a build-up of top hamper, reduction of forage value and productivity and animal production.
Recommended stocking rates27 Natura Rainfall Stockin l (mm) g Rate Region (ha/LU) NR I >1,000 3.5 NR II >800 3.5 NR III 500-950 5.5 NR IV 400 8.0 NR V <400 12
Potential grazing capacity of grassveld types described by Rattray (1957) when in good condition (Gammon 1983)28 Veld Description Grazing capacity type (ha/LU) 1 Montane grassveld 2-3 2a Hyperrhenia grassveld 2.5-3.5 2b Hyperrhrnia-other species 4-5 veld 3 Heteropogon-other species 5-6 veld 4 Eragrostis-other species 7.5-10 veld 5 Aristida-other species veld 10-16 6 Cenchrus-other species veld 7.5-10
Grazing period29 Depends on: veld condition season stocking density veld type Frequent close grazing will reduce grass vigour Too long a grazing period will lead to more frequent defoliation of the more desirable species Too short a grazing period will lead to too light defoliation of certain species and accumulation of top hamper
Grazing period30 The rule of thumb in high rainfall areas (>700mm) in mid-summer is that the maximum grazing period in days should be no longer than 60 divided by the number of paddocks per herd. In early summer grazing period should be half that of mid-summer and in winter can be longer because the grass is dormant
Rest period31 A period of no graze after defoliation or grazing The objectives of rest are many and varied as is their timing and duration Rests Based on the requirements of the animals • For herbage accumulation (optimum intake) • To provide for herbage accumulation for conservation (hay, foggage, silage)
Rest period32 Rests based on the requirements of the plants • improve forage quality, species composition, plant density and vigour • seed production • seedling establishment • vegetative growth of the plant • promote rapid growth phase of the plant Rests for management purposes • To accumulate sufficient fuel for a prescribed late winter burn
Recommendations for grazing cycles in mid- summer33 Veld type Grazing Rest period period Sweet veld 3 weeks 35-45 days Sour veld 6 weeks >60 days
Removal of top hamper34 The accumulation of old grass in a tuft reduces the vigour of the sward by shading out basal buds and hinders grazing Control of top hamper accumulation Correct stocking rates, grazing and rest periods fencing off areas of similar vegetation type for a more uniform utilisation of the veld Trampling by cattle Cool fire just before the flush of grass in spring
Grazing systems35 Set Stocking Deferred grazing All livestock are managed Also called rotational as a single herd and kept resting in a single paddock e.g., split season system (whole farm) for the entire grazing is subdivided into grazing period one enclosure more than SR should be 20% less the number of herds. The than normal grazing extra paddock is afforded capacity a full rest for a season or Only SR is variable full year Continuous Grazing (set stocking) Grazed Grazed Rested
Grazing systems36 Rotational resting and grazing Rotational It incorporates both grazing rotational grazing and rotational resting (deferred grazing) simultaneously
Prescribed burning38 Fire is both inevitable and necessary for maintaining the structure and functioning of mesic savanna rangelands. Used for: removal of surplus vegetation (moribund material or top hamper) prevention of accidental fires suppression of tree recruitment and thus control bush encroachment
Prescribed burning39 Effects of a fire depend on: fire intensity Hot – control tree recruitment Cool – top hamper removal frequency of burning 4 years or longer Season Early summer burns – top hamper removal Late dry season burns - to control encroaching plants type of fire ground fires, surface fires and crown fires Head fire, backfire
Communal area grazing40 Tragedy of the commons Controlled grazing schemes Improving crop residue quality, collection and utilisation Incorporation of fodder and forage production in cropping systems leypastures on fallow land, contours and waterways fodder banks of multi-purpose legume trees Forage conservation (hay, silage)