rangeland management and improvement in zimbabwe

RANGELAND MANAGEMENT AND IMPROVEMENT TECHNIQUES IN

ZIMBABWE(NZIRA DZEKUVANDUDZA

NEKUCHENGETEDZA MAFURO MUZIMBABWE)

Eddington Gororo20 March 2013

Grasslands Research Institute, Marondera

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Outline (Zvatichakurukura)

1. Introduction (Nhanganyaya) The need for rangeland improvement Zvikonzero zvekuvandudza mafuro

2. Range improvement (kuvandudza mafuro) Rangeland improvement methods Nzira dzekuvandudza mafuro

3. Rangeland management (Kushandisa mafuro) Rangeland management techniques Kushandisa mafuro kwakanaka

4. Conclusion (Saka tiri kutii?)5. Discussion (Hurukuro)

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Need for rangeland improvementSei tichifanira kufunga nezvemafuro

edu? Deterioration evidenced by:1. Changes in grass species composition –

invader/increaser species (Sporobolus, Aristida)2. Proliferation of undesirable/invasive plants e.g.,

forbs3. Bush encroachment and tree recruitment – we have

to arrest plant succession at the grass stage4. Soil erosion5. Accumulation of top hamper and moribund

material Ultimately low animal productivity (growth rates,

conception rates, milk yields, grades)

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Changes in species compositionHuswa huri kushanduka mumafuro

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Undesirable & invasive plantsMiti nehuswa hwusingadyiwe

nemombe

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Bush encroachment and tree recruitment

Miti iri kuwanda kupfuura huswa

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Accumulation of top hamper Huswa hauchanyotsomera marara

awanda

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Grass tufts die out (become moribund)Zvidzitsi zveuswa zviri kufa

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Rangeland ImprovementKuvandudza mafuro

Kuvandudza kuita sei? = improving range (natural veld) condition

and productivity or facilitate more efficient utilization of the range.

Tinovandidzirei mafuro? (Reasons) increased forage yields and quality

goho remafuro rinokwirira higher stocking rates

tinochengeta mombe dzakawanda pahekita Increased animal productivity and daily

performance (better milk yields, higher conception rates, faster growth rates)

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Reasons for rangeland Improvement Tinovandidzirei mafuro?

Sustainable futureMafuro anoramba achiita zvakanaka mune ramangwana

Soil erosion control (ivhu harichaende nemvura kana mhepo)

Reduction of undesirable plants (miti isinei neufuro haizokuri)

Reduction of fire hazards (moto yesango inoita mishoma)

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Nzira Dzekuvandudza Mafuro1. Rangeland fertilization (kuisa fetiraiza

mumafuro)2. Control of undesirable plants (kubvisa miti

nehufuro husingadiwe)3. Range rehabilitation (kugadzirisa

zvakakanganisika)4. Reinforcement (kuwedzera humwe huswa)5. Replacement with sown pastures (kuisa

mafuro matsva)6. Improved grazing management

(Mashandisiro)

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Kuisa fetiraiza mumafuro

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

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Kuisa fetiraiza mumafuro

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)

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Control of undesirable plants Kubvisa miti nehufuro husingadiwe

These are plants that are: Not readily eaten by animals Less productive or reduce veld productivity Reduce amount of utilisable herbage Conflict with veld management

Undesirable plants: Invader and invasive species Poisonous species

E.g., Lantana camara, Dichapetalum cymosum, Urginea sanguinea, Solanum incanum (nhundurwa), etc.

Bushes and trees

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Control of undesirable plants Kubvisa miti nehufuro husingadiwe

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Control of undesirable plants Kubvisa miti nehufuro 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

practicing good veld management Prescribed hot burns (fire).

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Range rehabilitation (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.

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Rangeland Reinforcement (kuwedzera humwe huswa mumafuro aripo)

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.

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Reinforcement with legumes

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

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Natural veld with silverleaf

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Reinforcement with improved grasses

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)

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Rangeland reinforcement

High rainfall areas – Desmodium spp (heavier soils) Stylosanthes spp (lighter soils)

Low rainfall areas – siratro, cassia and Archer The benefits of rangeland improvement include:

greater range 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

recommended in Zimbabwe

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Replacement with sown pastures (kuisa mafuro matsva)

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 fertility from crops

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Replacement with sown pastures (kuisa mafuro matsva)

Permanent dryland pastures – star grass, kikuyu, napier grass, etc. species should respond well to nitrogen

fertilisation and withstand severe defoliation/grazing pressure.

Irrigated pastures very expensive form of production mostly used for finishing cattle and for

dairying. Ryegrass, Lucerne (alfalfa) and clovers are the

most suitable species for irrigated pastures.

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KUCHENGETEDZA MAFURO(Sound range and grazing management

principles)

Principles to be discussed1. Stocking rates2. Period of stay3. Resting 4. Top hamper removal5. Grazing systems6. Use of fire (Prescribed burning)

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Stocking rates

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.

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Recommended stocking rates

Natural Region

Rainfall (mm)

Stocking Rate (ha/LU)

NR I >1,000 3.5

NR II >800 3.5

NR III 500-950 5.5

NR IV 400 8.0NR V <400 12

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Potential grazing capacity of grassveld types described by Rattray (1957) when in good condition (Gammon 1983)

Veld type

Description Grazing capacity (ha/LU)

1 Montane grassveld 2-3

2a Hyperrhenia grassveld 2.5-3.5

2b Hyperrhrnia-other species veld

4-5

3 Heteropogon-other species veld

5-6

4 Eragrostis-other species veld

7.5-10

5 Aristida-other species veld

10-16

6 Cenchrus-other species veld

7.5-10

7 Aristida-dactyloctenium-Eragrostis veld

12-20

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Grazing period

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

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Grazing period

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

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Rest period

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)

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Rest period

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

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Recommendations for grazing cycles in mid-summer

Veld type Grazing period

Rest period

Sweet veld 3 weeks 35-45 days

Sour veld 6 weeks >60 days

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Removal of top hamper

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

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Grazing systems

Set Stocking All livestock are

managed as a single herd and kept in a single paddock (whole farm) for the entire grazing period

SR should be 20% less than normal grazing capacity

Only SR is variable

Deferred grazing Also called rotational

resting e.g., split season

system grazing is subdivided

into one enclosure more than the number of herds. The extra paddock is afforded a full rest for a season or full year

Continuous Grazing

(set stocking)

Grazed

Grazed

Rested

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Grazing systems

Rotational resting and grazing

It incorporates both rotational grazing and rotational resting (deferred grazing) simultaneously

Rotational

grazing

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Prescribed burning

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Prescribed burning

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

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Prescribed burning

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

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Communal area grazing

Tragedy of the commons Controlled grazing schemes Improving crop residue quality, collection

and utilisation Incorporation of fodder and forage

production in cropping systems ley pastures on fallow land, contours and

waterways fodder banks of multi-purpose legume trees

Forage conservation (hay, silage)

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NDATENDA