HIGH RAINFALL ZONE

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Farming zones in WANA

Overview of the zone

GUIDE  FOR FARMERS AND EXTENSION AGENTS

TECHNICAL BACKUP FOR EXTENSION PROGRAMS

POLICY MAKERS AND PROJECT PLANNERS

 HIGH   RAINFALL  ZONE

  ABOVE 500 mm

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CEREAL  ZONE

     500 mm  to 200 mm 

    Medic overview

Deep ploughing overview

Farmers' Guide to cereals and pasture

Farmer training kits

This is a major section of the site

What cultivar?

 How does your medic grow?

   MARGINAL  ZONE 
   

  250 mm  to 150 mm

 Tenure and grazing management

RANGELAND

Below 200  mm

Rangeland overview

Action plan for flockowners

Water harvesting

Introduction

The annual pasture legume and phosphate revolution (called the "sub and super" formula) that transformed livestock production in southern Australia over the course of the 20th century started in the High Rainfall Zone (over 500 mm).

The original cultivar of sub clover was Mt Barker discovered in South Australia in the 1880-90's.

Most of the Australian High Rainfall Zone has acid soils so during the 20th century there was a huge expansion of legume pasture cultivars for acid soils.

In the WANA region soils are more commonly alkaline rather than acid even in the High Rainfall Zone and the selection of pasture cultivars is more difficult particularly for rotations that require a considerable amount of hard seed.

There is no shortage of legumes suited to the zone. They have not been selected and become named cultivars.

It is generally accepted that the common cultivars of medic (see What cultivar for the cereal zone?) are not well suited to the High Rainfall Zone above about 600 mm.

In fact a FAO report on medics for Libya considered this to be so important that they printed a WARNING in heavy type to the effect that medics are not suited to high rainfall and humid zones.

It does seem a little strange. Except for a small area around Derna on the Jebel al Akhdar range I doubt whether any part of Libya has received anything near 500 mm average rainfall.

Other WANA countries do have considerable areas where the rainfall is greater than 500 mm and the FAO claim needs to be examined in greater detail.

The FAO warning is wrong on two accounts.

Medics are adapted to rainfall above 500 mm

Firstly the common cultivars of medic do have a greater range than 500 mm.

I have personal experience of excellent medic pastures on my farm in Australia where the rainfall was 550 mm and there were other medic pastures in areas with even high rainfall.

It is true however that medic cultivars that have been selected for the Cereal Zone are not well adapted above about 600 mm.

Even if they were well adapted farmers would need to look for other cultivars. As I explained with the Cereal Zone early season medics will grow in late season areas but they will flower too early to utilise all the growing season.

Similarly a medic selected for 450 mm will not utilise all the growing season in a zone with 650 mm.

More high rainfall medic available

 Secondly there is no shortage of medic for the High Rainfall Zone.

It is simply that Australian farmers and scientists have not selected and named cultivars for the zone.

I now have a farm in Italy in a zone with 850 mm and there are many medics growing in the natural pasture under my olive trees.

Given the naturally occurring medic it is possible to sow medic that is suited to a 500 mm zone in areas with 600 mm or more in the knowledge that over the years it will be replaced by local medics better adapted to that environment (including the longer growing season). 

Rotations and hard seed

In the Cereal Zone most of the common medics (the Gama medics being the major exception) have sufficient hard seed for the medic - cereal rotation.

It is important character in selection.

When medics are used on the parcour too much hard seed can be a slight problem for the initial establishment using pods but once the pasture is established it is a useful safeguard against drought and poor management.

If seed production fails in a single year the pasture regenerates from reserves of hard seed.

In the High Rainfall Zone many excellent cultivars of annual legumes do not have sufficient hard seed to use in a rotation dependent on natural regeneration after the cereal crop.

They are only suitable for permanent pastures.

With permanent pastures the legume regenerates mainly from the seed in the pod produced the year before. Some hard seed is a useful insurance against the failure of this main wave of germination.

While Zaghouan in Tunisia is in the Cereal Zone there is theoretically no reason why the Zaghouan 4 rotation could not be used in the High Rainfall Zone with other cultivars of medic or sub clover.

More of the pasture legume would germinate in the first cereal crop but early harvested pods, stored in a cool place should still contain a large amount of hard seed for the subsequent regeneration.

This should apply even with cultivars that have a high proportion of hard seed breakdown in a single summer. The pods in the sacks should avoid the effects of the first summer.

This hypothesis does need to be tested.

Legumes in long-term pastures

 
 
 
 
The above map shows the natural distribution of sub clover species. It can be seen that they are more common on the north shore of the Mediterranean but there significant area of the High Rainfall Zone of WANA where sub clovers can be found.

Below is a guide to maturity and rainfall used in further tables. Rainfall is not always a reliable guide to cultivar selection as the critical factor is the effective rainfall within the growing season. The rainfall figures below are the commonly available annual average rainfall.

Maturity

Days to first flowering

Minimum growing season length (months)

Rainfall - guide

mm

Very early

less than 85

4.0

Below 200

Early

81 to 95

4.5

200 to 300

Early/mid

91 to 110

5.0

Mid

106 to 125

5.5

300 to 400

Mid/late

121 to 135

6

Late

131 to 145

6.5

400 to 500

Very late

More than 140

7

Above 500

 Sub Clover

Ssp subterranean

The most commonly used sub clovers belong to the sub-species subterranean.

They grow on a range of soils from sand (not deep sands) to clay loams.

They are adapted to soil pH in the range 4.5 to about 7.

They have a wide range of adaptation to rainfall from the 250 mm to 750 mm and above.

Below is a selection of the late cultivars. There are many more but the extra choice can cause confusion.

CULTIVAR

MATURITY &

GROWING SEASON (Months)

HARDSEED

% at end of summer

COMMENT

Coolamon

Mid/late

6.5

30

Denmark

Late

7.5

10

Very persistent under grazing.

Goulburn

Late

7

30

Can be used with occasional cereal crops.

Leura

Very late

8

10

Tallarook

Very late

8.5

less than 10

Can cause ewe infertility.

Mt Barker

Late

7

less than 10

This is the original sub clover discovered by Amos Howard in the 1890's in South Australia. Has been replaced by Goulburn, Denmark and Leura.

Ssp brachycalcinum

This is another sub-species of sub clover that is adapted to neutral to alkaline soils.

The cultivars listed below are suited to the range of 400 to 600 mm but I am sure more could be found for higher rainfall areas if there is a demand.

CULTIVAR

MATURITY &

GROWING SEASON (Months)

HARDSEED

% at end of summer

COMMENT

Clare

Mid/late

6

10

The original ssp brachycalcinum found by a farmer near the town of Clare in 1921.

Nuba

Late

6.5

30

Antas

Late

7

20

Ssp yanninicum

This is the sub-species that gained notoriety through the cultivar Yarloop. This cultivar is highly oestrogenic and can cause ewe infertility when dominant in a pasture.

The sub species is highly resistant to water-logging and where this occurs there may be clover dominance as other clovers or grasses are not so well adapted.

New cultivars below have all been selected for low oestrogen.

CULTIVAR

MATURITY &

GROWING SEASON (Months)

HARDSEED

% at end of summer

COMMENT

Riverina

Mid

6

20

Suited to occasional cropping

Trikkala

Mid

5.5

10

Gosse

Mid/Late

7

20

Larisa

Late

7.5

10

Napier

Late

7.5

30

Meteora

Very late

8

30

Arrowleaf clover - Trifolium vesiculosum

Grows in a similar range of soils to sub clover but can stand a slightly high pH of 7.5.

It is very deep rooted and stays green after most clover has dried off. Is well adapted to deep sandy soils.

CULTIVAR

MATURITY

HARDSEED % at end of summer

Cefalu

Very late

60

Seelu

Very late

60

Zulu

Very late

60

Arrotas

Very late

90

Balansa clover -Trifolium michelianum

This clover already gets a mention in the Cereal Zone.

Has an even wider adaptation to alkaline soils up to about pH 8

Cultivar Bolta with about 50% hardseed is best suited to high rainfall areas.

Berseem clover - Trifolium alexandrinum

Already widely grown in the WANA region but mostly under irrigation. Used in Egypt extensively as an irrigated fodder.

Adapted to soils in the range of 5.5 to 8.

Its great drawback is a total lack of hard seed. Regeneration can be poor after drought or a false break as there are no reserves of hardseed in the ground.

Persian clover - Trifolium resupinatum

Adapted to clay soils with a pH in the range 5 to 8.

The cultivars with hardseed persist well as a permanent pasture but those without hard seed may need to be reseeded. In fact they are probably better as cut forage or hay crops.

CULTIVAR

MATURITY

HARDSEED. % at end of first summer.

Prolific

Mid/late

30

Nitro Plus

Mid/late

30

Kyambro

Very late

30

Lightning

Mid/late

0

Maral

Very late

0

Morbulk

Very late

0

Laser

Very late

0

Leeton

Very late

0

Perennial Legumes

Perennial legumes can be used in the High Rainfall Zone. They have been recommended by people with northern temperate training and experience as they fit into their idea of a pasture plant. In fact they have some advantages and some disadvantages

Their greatest advantage is the stability of the pasture composition. They are not so susceptible to variations in seed production and germination.

A pasture composed of annual legume species is dependent on seed production in the spring. If that fails due to drought or over-grazing the pasture will be weakened. Hardseed provides a buffer against a single seed production failure. Continual failure due to over-grazing will destroy the pasture.

The pasture is also dependent on the germination in autumn. If that fails a second germination is possible from reserves of hardseed.

The perennials are there all the time.

The problem with perennials is that they cannot form a dense pasture in zones with dry summers. The plants thin out in summer due to competition.

If there is a severe drought this can be serious. In winter there is a "gap" in the pasture environment that is filled by annuals.

Some perennials can self-seed and form a dense pasture but in most cases the gap is filled by annual grasses and weeds.

Lucerne - Medicago sativa

Lucerne or alfalfa is widely used in the WANA region under irrigation but it can be used as a rainfed pasture also.

There are too many cultivars to include here but the selection should be based on the degree winter dormancy/activity.

The winter dormant cultivars are suited to areas with very cold winters.

Winter active cultivars are better for most areas.

Highly winter active cultivars are only suited to pastures of 2 to 4 years as persistence is poor after that.

Lucerne pasture must be rotationally grazed rather than the continuos grazing recommended for annual medics.

Caucasian clover - Trifolium ambiguum

Well adapted to cold areas with an altitude of over 800 m. Acid soils. Seedling vigour is poor and the clover may take a few years to become properly established but can then be heavily grazed.

Cultivar Endura.

Red clover - Trifolium pratense

This clover is a biennial or a short-lived perennial.

Again suited to colder areas.

Adapted to acid soils in range of pH 5.2 to 7

The main cultivars are: Broadway, Claret, Crossway, Grasslands Pawera, Grasslands Turoa, Redquin, Redwest, Renegade, Sensation, Astred, Grassland G 27 and Grasslands PAC 19.

Strawberry clover - Trifolium fragiferum

A very tough pasture legume that persists well under heavy grazing. Has been used widely in the High Rainfall Zone of Australia for many decades.

Adapted to soils pH in the range 4.8 to 8.0. It will survive and even thrive in waterlogged soils and those that are saline.

The main cultivars are:- Palestine, O'Connor's, Grasslands Onwards. Grasslands Upwards.

White clover - Trifolium repens.

This is the classic clover used in northern temperate regions before being eliminated by the use of nitrogen fertiliser.

It will grow in the cooler and higher rainfall parts of the WANA region. Frost tolerant.

It is also grown sometimes in warmer areas under irrigation.

Main cultivars:-Haifa, Tamar, El Lucero, Osceola, Kopu II Grasslands Kopu, Waverley, Aran, Will Ladino, etc.

Grasses

If your indoctrination with northern temperate ideas is so strong that you cannot completely accept the idea of a legume pasture without grass then you will need to sow grasses that are adapted to the High Rainfall Zone of WANA.

In general you will be looking for versions of the familiar ryegrass and cocksfoot as well as Phalaris with strong winter growth and summer dormancy.

The cultivars from northern temperate region with summer growth and winter dormancy are not suited to the region.