Permaculture Designers Manual
CHAPTER 10 –
THE HUMID TROPICS IN PERMACULTURE
Section 10.13 –
Grassland and Range Management in Permaculture
In view of the prevalence of livestock enterprises in the tropics, some guides to management are required for milk and beef or sheep production.
The following management strategies can be implemented:
THE ADDITON OF FORAGE SPECIES to grasslands. These can be grass legumes or trees; the latter providing foliage, food sugars, seed carbohydrates or fruits.
ENVIRONMENTAL CHANGES, particularly in terms of water storage and soil structure, irrigation windbreak and shelter. Key fertilizer or trace elements can be added and plant species can be maintained by slashing or light cultivation of pasture.
CONSERVATION OF FORAGE by rotational or periodic rests from grazing, by using hays and silages, by supplying protein or urea supplements and molasses in drought and by keeping stocking rates below the worst case conditions.
STOCK MANAGEMENT, especially by well planned buying and selling to keep numbers in tune with seasons and longer-term fluctuations, for example timing calving or buying in animals in spring or early summer and selling them or dry cows in autumn to lessen winter feed demand.
At the extreme, stock can be penned and fed harvested fodders. A sequence of species or a species polyculture can be planted to take best advantages of forages.
A mixture of legumes with a selected grass species plus some storable forage is ideal for the tropics.
Most grazing systems can extend under palms, between large tree crops, or as a complex with belts of forage tree legumes yielding fodder, fruit, pods or large seed for food concentrates.
Each soil type, location, rainfall area, slope type and main crop needs assessment and planning.
The leaf swards valued by grazers may also suit green-crop cover for orchardists where regular slashing for easy fruit harvest is practiced (or sporadic grazing).
In these cases it is essential that the orchard crop is well established using manures before twining legumes are planted.
Soils under slashed pastures are of excellent structure and erosion is effectively stopped.
Elephant or banna grass (Pennisetum purpureum) is best on deep alluvial or coarse flats above 110cm (alluvium) or 90cm (coastal) rainfall it reaches 2.5-4.5m high, but can be grazed to 1m or cut to 15 cm for forage and mulch.
It needs a vigorous legume, e.g. Leucaena interplant or forage legumes such as Calopogon, Centrosema, and Glycine (in high rainfall tropics).
If a cool season is expected, autumn cutting should be later so that cool season re-growth is obtained Banna grass can be set out as windbreak by burying hard slim pieces of 4-5 nodes horizontally at 8-10cm depth in summer.
Furrows should be manured and kept free of weeds until the stems shoot strongly.
Permanent plots can be established, well-suited to feeding selected stall-fed dairy cattle.
Accessory plots of bean trees, coconut, banana, etc. for diet variation and palms for bedding are ideal. Banna grass can carry 7 milk cows/ha if cut and hand-fed with Leucaena and sugar pods.
TROPICAL PASTURE GRASS SPECIES
Guinea Grass (Panicum maximum):
This is a bunch grass for warm areas of more than 90-300cm rain. It is drought resistant but yields best in humid areas.
Frost sensitive, Shade tolerant and suits crowned tree crop (often yields well under trees). Valuable in that growth is maintained in cloudy summer-autumn regimes.
Grazed down to 15-20cm. Combines well with twining legumes which climb on stiff stems. Suits rotational grazing (12-18 fields), interspersed with sugar-pod trees and tree fruit forages.
Drill it to 6mm to establish a first choice for sub-tropic and tropic pastures.
Kikuyu Grass (Pennisetum clandestinum):
Cold tolerant and grown from cool to tropical areas. They are valuable for cooler uplands and thinner soils.
They have good autumn growth, when nitrogen-fixing trees (Acacia, Leucaena, Prosopis, or Albizzia) are established.
Prefers light soils, red loams and can be sown as runners or seed.
They are excellent for water spillways and erosion control.
Few legumes tolerate the tight sward, so that trees for nitrogen are essential.
Desmodium, Glycine and white clover sod-drilled in autumn cut areas can be tried.
Makarikari Grass (Panicum coloratum):
Bunch and spreading types for 40-90cm rainfall. This grass tolerates alluvial fans, flood plains, black clay soils, red earths and even semi-caked salted soils.
It needs a year after seeding to establish, so it suits rotational systems.
Lucerne interplant can succeed in irrigated areas. Drilled at 1.3cm, 2-3kg/ha or planted from rooted cuttings.
It is valuable for winter-green feed or drought resistance. Suits long rotation grazing in open savannah of Acacia, sugar-pod trees.
On black clay soils, purple pigeon grass (Setaria porphyrantha) may germinate better than makarikari.
Para Grass (Brachiaria mutica):
For warm areas of low frost intensity, valuable for swampy soils and at soaks, dams, waterholes.
It provides good soil structure due to fibrous shallow roots. It can be grown with the forage legume phasey bean, greenleaf Desmodium, Centrosoma, or puero.
It is ideal as a fenced-out reserve food for drought, to finish off animals for sale in poor seasons.
Planted from cuttings at 2x2m or seeded if seed is available.
Do not plant where clogging of channels can be a problem or where other crops are to be grown. Can reach 4m in one summer!
Sorghums (Sorghum almun), silk sorghum, and Sudan Grass (S. halapense):
These are annual, biennial, or persistent from seed and are of most use as broadcast sown pioneers in slashed mulch at 50-90cm rainfall.
They can be used as pioneers with the perennials, as mulch in orchard strips, as emergency dry-season fodder and as a garden mulch source.
Easily grazed out, the sorghums provide birdseed, forage and help control weeds.
They are of particular use in early establishment and can be surface sown.
Establishing perennial grass swards on weedy or eroded areas is a one to three year process.
The best way to proceed is:
- Choose a land-forming system such as swaling, interception banks or pitting. Try to establish some dams for irrigation above good soil types.
- Sow a pioneer grass such as molasses grass, Sorghum almun, or silk sorghum mixed with sawdust onto slashed weeds or drill selected grass and legumes after slashing.
- Burn molasses grass or drill selected perennials and broadcast Sorghum almun.
- Concurrently with earth-forming, plant a mixture of leguminous trees along swales, through the area to be grassed at 30-100 meter strip spacing. Allow 2-3 years to grow with light grazing to year 3.
- Commence managed rotational grazing and drill or broadcast forage legumes into established grasses. About 15-18 fields are necessary for rotation. On irrigated areas, some strip grazing is possible (use electric fences).
On rocky knolls, leguminous tree pioneers followed by kikuyu sward may succeed.
Early furrows of banna grass provide erosion and wind control (at 30m spacing) until tree legumes establish.
At every stage, soil analysis and minimal mineral fertilizer amendments may be necessary and with intensive grazing, sulfur and potash dressings are desirable.
TROPICAL FORAGES AND GREEN CROP
Desmanthus virgatus is a shrub to 3m resembling Leucaena and tolerant of heavy cutting and browsing in the savannah tropics.
It is vigorous and seeds are prolific, thus should be on range, not in field crop (7-70 ton/ha /year).
Desmodium discolor is a browse shrub to 3m, yields some 30 ton/ha/year green fodder and is sown prior to rain as strips in rangeland.
Also, it is compatible with maize.
Perennial to 2m. Good on acid soils (2-7 ton/ ha/year).
Grows as a shrub to 4m, tolerates wet sites in tropics and can be cut for forage (stems brittle).
It is excellent forage and has a wide soil range in the tropics. It is a pioneer plant in grassland and can be cut for forage.
Tagasaste (Chaemocytisus palmensis):
It is tolerant and hardy in the tropics cool areas, widely used In New Zealand in dry areas for cut forage, pioneer, mulch and nurse crop.
Honey Locust (Gleditsia triacanthos): Selected trees bear heavy loads of pods in dry subtropics; frost-hardy thorn-less form exists.
Deep soil moisture is required in the dry season, but the tree is soil-tolerant and wind-hardy. Best trees are thorn-less, high sugar types.
Kiawe (Prosopis pallida): Staple pod forage on dry savannah sites in subtropics, dense wood, excellent firewood and termite resistant posts, 20% thorn-less trees on Hawaii. It is non-invasive.
THE PASTURE LEGUMES OR FORAGE LEGUMES
Calapo (Calopogonium mucunoides): A short lived twining perennial used mainly as a pioneer of burnt or slashed weed areas to smother weeds before permanent systems are established.
It is suited only to low-frost coastal areas of high rainfall (above 125 cm) and is moderately shade tolerant it reseeds, but shades out or can be grazed or cut out. It has high seedling vigor.
Centro (Centrosema pubescens):
A twining perennial used in both pastures and grain crops.
It prefers more than 125cm of rain, warm climate between the tropics. It is an excellent cut forage and soil-builder, tolerant of wide soil range, acid soils, short flooding and some frost.
Ideal for guinea-grass permanent pastures, banna, pangola and para grasses.
It can climb to 14m so it is not suited to short perennial crops, bushes, small trees.
It can be broadcast in burns or slash areas or drilled. Seeds may need hot water treatment or inoculation. It persists well under grazing.
Kenya White Clover (Trifolium semipilosum): This plant persists well in short grass pastures, dairy strip grazing (more than 100cm rainfall or irrigated).
It flowers in autumn and spring and needs a good seedbed, scarification and inoculation.
Haifa White Clover (Trifolium spp.):
Strain adapted to summer heat, subtropics, it persists well, reseeds after drought, good interplant together with woolly vetch.
Greenleaf Desmodium (Desmodium intortum):
Vigorous trailing perennial used as understory in tall orchards (after establishment).
It is affected by frost, needs more than 100cm rain, but valuable for soil-building in sandy soils, for early spring and autumn growth.
Tolerant of poor soils and stands some waterlogging.
Needs rotational grazing, seeds need inoculants, a companion legume is Glycine for wind control.
Silverleaf Desmodium (D. uncinatum):
Trailing vigorous perennial for mulch in established orchards, rocky sites, pastures, wet (not boggy) areas and acid soils.
Pods sticky and some people get skin rashes if it is used in gardens.
Macro (Macrotyloma axilare):
Twining perennial forming a dense sward. It needs more than 100cm rain in light frost areas.
Valuable in shallow ridge soils, tolerates some dry periods. It establishes readily.
Lab-Lab (Lablab purpureus):
Vigorous annual or short-lived perennial useful for soil-building and weed control.
Grown as a forage and mulch legume wherever cowpeas succeed.
Will stand sporadic grazing; kept in rotation or strip grazing. Good silage, compost, mulch, pioneer crop.
It can tolerate acid soils and rough seed-beds. Broadcast at 20kg/ha, drill at 6-10kg. Inoculation assists establishment.
It is a good screen plant on trellis for watered dryland gardens. Pods and beans are edible.
Glycine (Neonotonia wighti):
Slender, twining perennial with deep roots. It cycles phosphates from deep soil layers.
Resists drought well, but affected by frosts. It is useful in cool subtropics and tropics.
Good winter growth in pastures; main growth in summer. It is often fenced out in late summer or early autumn as a winter reserve.
Rainfall is ideal at 80-180cm. It does best on well-drained deep red soils, but also yellow clays and black cracking soils, areas not subject to waterlogging.
It needs rotational grazing with rest in late spring.
Good silage (with molasses), mulch, fertility restoration of soils.
Good seedbed and inoculation is desirable.
Lucerne (Medicago sativa):
Grown from cool temperate to tropics, usually as a pure sward cut to baled hay, but also in well-managed pasture under rotation (allowing a year or so of light grazing).
It needs a minimum of 55cm of rainfall, as it is deep rooted. It combines well with makarikari, sorghum.
Regular resting is essential to persistence, and in pasture needs re-seeding every 4-8 years. Cut for hay just before flowering.
Reseeded in cut sward by chisel seeding. Inoculation is essential and lime pellets are also essential in acid soils. 6-14 kg/ha sown, lighter on rain-fed areas, heavier if irrigated.
Silage with molasses is now popular, hay expensive and in high demand.
Garden plots used for mulch, rabbit feed, seeds for sprouting.
Phasey Bean (Macroptilium lathyroides):
Self-regenerating annual, long erect twining stems.
It needs more than 75cm of rain and heavy soils.
It can be sown with para grass in swampy areas and also with Glycine.
Siratro (Macroptilium atropurpureum):
A perennial legume it creeps and has a good root system.
Warm areas with 75cm or more of rain, ideally 90-110cm. Poor soil tolerance, excellent contribution of nitrogen to grasses, e.g. Rhodes grass.
Ideal for rotational grazing, readily established, resistant to nematodes.
The basis of many excellent pastures.
Puero (Pueraria phaseoloides):
Pioneer green and cover crop, perennial climber.
It is very vigorous as a smothering summer mat.
It is used in wet tropics. Palatable, good seedling vigor (can be broadcast).
It can be kept in pastures if rotational grazing is practiced, but is also suitable as green manure, orchards or as a garden mulch crop.
Stylo (Stylosanthes guianensis):
Perennial pasture legume of warm areas, 90-400cm of rain.
Good pioneer of poor acid soils, poor drainage, sands, rocky soils, hillsides.
It combines well with low grasses (signal grass, pangola).
It is sensitive to copper and phosphate deficiencies.
Excellent mulch in tree systems in such soils and can be cut to silage.
Surface-planted, wide range of inoculants. Many varieties and is suited to specific sites and climates.
Some shrubby types are an excellent cassava interplant but also suits banana or papaya once plants of fruits are established and as a slash mulch; often kept as a feed for dry season, suits fenced-off reserves (seca variety)
Shades out in dense plantation but may be ideal establishment mulch.
Cowpea (Vigna sinensis):
A preferred annual cover crop and soil improver. It is also good with sorghum, maize and millet as a hay or mulch in established orchards.
Lupin (West Australian varieties of seed lupins):
Excellent cover crop and seed in acid sandy or good soils.
If it is inoculated it can be broadcast or sod seeded. Good winter green crop (annual) in vines, bush fruit crop.
Mung Beans (Vigna radiata):
A vigorous garden green crop, forage annual, hay or grain crop.
Suits gardens and low crop systems. It is an annual.
Note: Serious attempts to establish green crop and productive perennial pasture should be prefaced by research into species.
An excellent place to start is:
Humphreys, L.R. A Guide to Better Pastures for the Tropics and Subtropics, Wright Stephenson & Co. Pub. Australia P/L, P.O. Box 113, Ermington, NSW 2115