COVER CROPS/LIVING MULCH

Cover crops provide a living carpet of perennial plants for orchards. A ‘living mulch’ of low-growing legumes can provide many advantages, especially compared to grass, which aggressively competes with your fruit trees for water and nutrients.

Cover crops can:

- Suppress weeds without the use of herbicide.
- Protect valuable topsoil from wind and water erosion.
- Reduce compaction caused by frequent mowing.
- Increase organic matter, earthworms & beneficial micro-organisms.
- Increase the soil's available nitrogen and moisture retention.
- Bring deep minerals to the surface and break up hardpans.
- Provide habitat, nectar & pollen for beneficial insects and reduce populations of pests.
- Improve water, root & air penetration in the soil.

Plant species should be selected for suitability to climate, ease of establishment, perennial habit, nitrogen-fixing capacity and shade tolerance. Avoid climbing legumes such as Lablab. Aim for a flowering meadow in your orchard rather than sterile, bare earth or a grass ground cover.

GETTING STARTED
Growing a cover crop is particularly easy in new orchards as the soil can be cultivated. The seed is then spread as evenly over the area as possible followed by raking to cover the seed. In established orchards a variety of techniques may need to be used. Poultry in movable cages can be used to bare the ground, which is then sown with seed. Alternatively an organic herbicide can be used to kill any grass or an area can be mulched with newspaper and hay until the grass has died.

WHAT IS A LEGUME?
Legumes are plants such as clover, lucerne, peas, beans, medics and chickpeas. An important advantage of legumes is their unusual ability to obtain nitrogen, a major element needed for plant growth, from the soil air, as most plants are unable to do this. They do this by forming a symbiotic relationship with a group of bacteria called Rhizobium, which live within a specialised structure, called a nodule, on the plant's roots. The Rhizobia can take nitrogen (N2) from the air and convert it to the form plants normally obtain from the soil. This process is called nitrogen fixation

WHY INOCULATE?
Rhizobia occur naturally, but they are very host-specific, that is, any one species of Rhizobia will only live with a few different types of legume. Consequently, when sowing legumes, the seed should be coated with a culture of the correct Rhizobium before sowing. This is referred to as inoculation. The bacteria are stored in peat, and as this is a living culture, it must be treated with care. It should be stored in the fridge and used within 3 months. To use, moisten the seed with a small amount of water and stir in the inoculant until seeds are coated. Then to allow even spreading of the seed over the seedbed, mix in enough agricultural lime, superfine lime or rock phosphate to dry the mixture out (use approx. 6 g of lime to 100 g of seed). This is called pelleting and makes fine seed easier to spread. Do not inoculate the seed until you are ready to sow it and do not leave the inoculated seed in the sun.

PLANTING TIPS
- Check the pH, legumes dislike acid soil
- Correct any nutrient deficiencies (except nitrogen) before sowing
- Cover the seed to a depth of 2-3 times the width of the seed & firm the soil
- Irrigate in all but rainy weather for best results
- It is important to select both summer and winter vigorous ground covers to reduce weed invasion.

SUGGESTED SPECIES:

Barrel Medic
Medicago truncatula

A drought hardy, prostrate relative of lucerne, this is an annual legume that will self-seed every autumn to give winter cover in frost prone areas. In temperate areas sow March-May or August-October; in subtropical areas sow May-July.

Lotus ‘Sunrise’

Lotus pedunculatus

A prostrate perennial forage legume with attractive yellow flowers; it is summer and autumn active and tolerates wet, acid and infertile soils. It requires a min. annual rainfall 600 mm. It is shade tolerant which makes it useful in established orchards. In temperate areas sow March-May or August-October; in subtropical areas sow May-July.

Lucerne 'Sequel'

Medicago sativa

'Sequel' is a bushy upright, winter vigorous, legume with a deep taproot, it requires a deep, well-drained fertile soil. It is attractive to beneficial insects and bees, can be cut for mulch and is a great animal forage. In temperate areas sow March-May or August-October; in subtropical areas sow May-July.

Lucerne 'Hunter River'

A bushy upright, spring and summer vigorous legume with a deep taproot, it requires a deep, well-drained fertile soil. It is attractive to beneficial insects and bees, can be cut for mulch and is a great animal forage. In temperate areas sow March-May or August-October; in subtropical areas sow May-July.

Maku Lotus
Lotus uliginous

Legume to 30 cm high, spring and summer active; tolerates acid and infertile soils and flooding; shade tolerant so it is useful in established orchards; animal forage. In temperate areas sow March-May or August-October; in subtropical areas sow March-June or spring.

Pinto's Peanut

Arachis pintoi

Excellent legume groundcover for orchards, Pinto’s forms a thick, luxuriant mat 20-30 cm deep, with attractive yellow pea flowers; it suits frost-free areas and is moderately tolerant of shade and drought tolerant. Subtropical areas sow October-January; tropical areas sow during the wet season.

Red Clover
Trifolium pratense

A summer vigorous, biennial legume for orchards; also useful as a green manure and bee forage. It has a bushy habit to 40 cm high & is drought tolerant. In temperate areas sow March-June or August-October; in subtropical areas sow May-July.

Shaw Creeping Vigna

Vigna parkeri
A summer vigorous, perennial legume with attractive blue flowers that forms a dense mat 30 cm deep . It is tolerant of dense shade and competes well with grasses such as kikuyu but needs moisture to do well. In subtropical areas sow October-January; in tropical areas sow during the wet season.

Villomix

Aeschynomene villosa

Perennial legume for orchards; self-sows readily; grows outwards rather than upwards on stems 1.5m long and up 60 cm high; it tolerates regular mowing. It is useful as an animal forage. Sow spring, summer, autumn with rainfall. Does not require inoculation. Suitable for subtropical and tropical areas.

White Clover
Trifolium repens

A year round cover in temperate areas, also useful as a winter cover in the subtropics. It attracts parasitic wasps of aphids and scales and prefers moist, well-drained soil. It is intolerant of shade. In temperate areas sow March-June or August-October; in subtropical areas sow March-June or spring.

Wynn's Cassia
Cassia rotundifolia

A spring and summer vigorous, perennial legume to 40 cm high, it dies back in winter. It is also useful animal forage and self-sows prolifically. In subtropical areas sow October-January; in tropical areas sow during the wet season.

DISCLAIMER:

No liability will be accepted by Green Harvest, its owners or employees as to the accuracy of any information. No responsibility will be taken for damage to property or persons due to information given about a product or technique. No responsibility will be taken for the loss of a crop or income due to information given about a product or technique.