Maku lotus - a legume groundcover for subtropical orchards

Series: Agnote DPI-333  Edition: First edition  Last updated: 20 Jul 2000

 

Maku lotus or greater lotus (Lotus pedunculatus) is a low growing perennial groundcover, suited to orchards in high rainfall areas of the NSW north coast. It was originally bred in New Zealand as a summer growing pasture.

It can be useful in young orchards less than five years old since it is easy to sow and establish and less competitive with trees than most grasses. Maku lotus combines well with some grass species to form a useful grass-legume sward.

Features of Maku lotus

  • It is a nitrogen-fixing legume.
  • It is a low-growing perennial - maximum height is 30cm providing year-round soil cover.
  • It tolerates some shade, so will survive in orchards where light intensity is low - but it is not as shade tolerant as Amarillo peanut and some grasses.
  • It will tolerate competition from grasses after it has established for 2-3 years.
  • It has some drought hardiness, tending to die off in patches in hot, dry spring and summer conditions. It shoots again when conditions are favourable.
  • It has some frost tolerance. Frost will kill leaves and stolons but established plants will shoot again in spring.
  • It will grow well on acid soils with a pH less than 5 and high levels of aluminium and manganese.
  • It is not a host for common pests and diseases of orchard species.

Drawbacks of Maku lotus

  • It is usually slow to establish, not forming a dense stand or tolerating competition in its first two years.
  • It is susceptible to glyphosate and young plants are killed.
  • It may compete with young trees, especially if it is growing near their trunks.
  • It is not suitable for ground cover in dense shade.
  • It is not recommended for use in bearing macadamia orchards because light is low. Its stolons - above ground stems - tend to tangle in harvest machinery.

Growth Habit

Maku lotus has five leaflets on a leaf stalk - three at the tip and two near the base where the leaf stalk joins the stem. It spreads by stems growing along and below the ground - stolons and rhizomes. These stems root at the nodes, from which new plants grow. Yellow, pea-like flowers form in summer and a cluster of seedpods, resembling an inverted bird’s foot, sets in late summer.

On the north coast Maku lotus growth is slow during a dry spring season and is most rapid from mid-January to late March, when rainfall is reliable and temperatures less extreme.

Land preparation

In an established orchard use a registered herbicide to kill any grasses. Less competitive grasses, such as carpet grass, can be mown short or burnt off with paraquat and oversown. A light scarifying to promote soil-seed contact improves germination.

When preparing ground for a new orchard, sow a grass-legume mix into a prepared seedbed after tree rows are mounded. There are several techniques for establishing Maku lotus in a prepared seedbed:

  • Spray with a registered herbicide to kill all existing vegetation, plant a high bulk annual legume such as dolichos in the spring-summer, kill off with herbicide in autumn and follow up with Maku lotus and oats/rye.
  • Mix a lower-than-normal rate of a high bulk annual, such as lupins, with Maku lotus and rye. Slashing the lupins in spring will allow the lotus and rye to replace them.
  • Sow a mixture of low-growing perennial grasses and legumes such as lotus, annual or perennial rye and kikuyu or bahia grass in late summer-early autumn. Haifa white clover can be added at low rates to provide additional cover in the first two years of establishment.

Plant your orchard trees when the groundcover is established, disturbing it as little as possible. For example, spray planting sites 0.5-1m in diameter with herbicide and then plant into these areas along the proposed row.

Sowing rates

Before sowing, inoculate Maku lotus seed with Group D inoculum to ensure roots become effectively nodulated for nitrogen fixation. Coating seed with molybdenum trioxide will enhance this - and it is more effective than using molybdenised superphosphate. Seed is usually lime pelleted with fine agricultural lime after inoculation to reduce the effect of acid soil on bacteria in the inoculum.

A sowing rate of 4-5kg/ha, which is higher than the rate used in pastures, is recommended. This rate will ensure a high plant population to help the Maku lotus compete with grasses and weeds during est-ablishment.

Maku seed can be sown alone or with less aggressive grass species. If you are sowing other species with Maku lotus, reduce the sowing rate of those species to half the recommended rate to reduce competition.

Where several species are being sown they can be mixed after the legumes have been inoculated to provide sufficient bulk to enable an even spread of seeds. Fertiliser can also be spread at the same time, provided mixing with seeds is done just before sowing.

Seed and fertiliser can be sodsown in the interrow of orchards or broadcast by machine or by hand. Apply superphosphate at a rate up to 500kg/ha. The rate depends on paddock history, as indicated by soil tests.

Sowing time

The usual dry spring on the north coast makes it difficult for small-seeded species such as Maku to establish, so it is sown here in autumn (March-April). It germinates before winter and is well established by spring. If moisture is available, Maku lotus can also be sown in February. Do not sow after April, as it is very slow to emerge when the soil temperature falls below 10°C.

Management

Maku lotus must be managed carefully in the first two years after planting. There will be few plants in the first year, but their numbers will increase in the second and subsequent years. Allow plants to seed to help increase stand density. Avoid mowing in autumn to enable seed to set and help it spread until it is well established.

Avoid low mowing in the first two years and control competition from companion grass plantings and weeds. Kill off grasses with appropriate registered selective herbicides. When established, Maku lotus needs to be mown at least twice in summer to reduce harbour for rats. Strategic mowing in good growing conditions will help reduce grass competition, but not disadvantage lotus.

In young orchards established stands of ground-cover, with thick growth encroaching near the tree trunk, may need to be suppressed with a registered desiccant herbicide in spring.

Fertiliser

Maku lotus requires only low maintenance rates of fertiliser. Apply an orchard interrow topdressing at a rate of 200kg/ha each year from the second year after planting. If orchard fertilising extends to the interrow there is no need for a special topdressing for lotus.

Performance compared with other legumes

Maku lotus is a useful horticultural groundcover. It forms a thick mat that protects the soil and helps reduce erosion, especially on sloping land. It is not as competitive in orchards as Amarillo peanut and some grasses because it is not as deep-rooted and does not produce as much dry matter. Nevertheless, it can be over-competitive with young trees if it is not controlled near the tree.

Maku lotus does not establish as quickly as clovers or peanut and may not persist in very low light in older orchards.

Summary

Maku lotus is a useful leguminous orchard ground-cover, suited to the subtropics and adapted to acid red soils. Although it establishes slowly and is sensitive to competition, it will eventually form a dense mat that will protect the soil from erosion. It can be managed to avoid harbouring vermin and competition with orchard trees.

Further information

For more information contact your local district agronomist or horticulturist. Related publications available from your local NSW Agriculture office are: