PDC LESSON 4.16 SOIL – WHAT IS A LEGUME
PDC
LESSON 4.16 SOIL – WHAT IS A LEGUME
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. Legumes are plants such as clover,
lucerne, peas, beans and chickpeas.
When to sow green
manure crops Winter
until late April –
May before sowing winter green manure crops; in frost-free areas these seeds
can be sown right through winter, until early August.
B.Q. Mulch ™ Nature’s control for nematodes! Brassica spp
Selected blend
containing the highest levels of bio-fumigant compounds combined with high
organic matter production; helps to control soil-borne diseases including fungi
and nematodes; also breaks up clay soils with its strong taproot and chokes out
weeds.
Fenugreek Trigonella
foenum-graecum
Adds nitrogen,
germinates in very cold soils, excellent for loosening heavy clay soils; seed
used in curry. Sow in subtropical areas
April-June.
Lupinus alba
Adds nitrogen,
long taproot opens and aerates the soil; accumulates phosphorus; flowers are
attractive to bees and other beneficial insects. Sow in temperate areas autumn
and spring, in subtropical areas
April-June. Inoculant included
Oats Avena sativa
Combines well with
all cool season green manures; helps control nematodes; produces bulk organic
matter, suitable for a wide range of soils. Sow in subtropical areas March –
June.
Rapeseed Brassica napus
Useful to control
soil borne diseases and nematodes by the release of bio-fumigants; breaks up
clay soils with its strong taproot. Sow in temperate areas late autumn to
spring; in subtropical areas May – July.
Subclover Trifolium
subterraneum
Self-sowing, adds
nitrogen, used to create an on-site mulch that doesn’t need cutting; in
temperate areas, subclover will die back in summer and regrow in autumn; does
well in acid soils.
Sow in subtropical
areas May-July.
Inoculant included
Summer
As a general guide
sow in spring after all danger of frost has passed, usually mid-September; sow
whenever good rainfall is expected; in tropical areas seeds can be sown right
through the year whenever moisture is available. More specific sowing times are
listed as part of the seed description:
Cowpea Vigna
unguiculata
Adds nitrogen,
builds organic matter, smothers weeds and controls nematodes; combine with
Japanese millet; use as a living mulch under corn; good animal forage; some
drought tolerance.
Sow in subtropical
areas Sept-March and in tropical areas during the wet season.
Japanese Millet Echinochloa
utilis
Fast growing
clumping grass, good used with legumes as a green manure, adds bulk organic
material. Sow in subtropical areas Sept-April and in tropical areas during the
wet season.
Lablab purpureus
Adds nitrogen,
likes it hot, very vigorous vine; suits a wide range of soils and wet weather;
useful animal forage, some drought tolerance. Sow in subtropical areas Oct-Feb
and in tropical areas all year.
Text from the roots, Elisabeth Ferkonia (Aus.) PDC studied with Bill Mollison,
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