Indigenous crop production: The leafy greens of the amaranth

Amaranths (family: Amaranthaceae) have their origins in the Americas, but have been global travelers and settlers for thousands of years and are said to be among man’s oldest food crops. Beetroot, spinach, chard and quinoa are also members of this family.

The amaranth is a pioneer species that will quickly colonise degraded and disturbed areas such as roadway verges and old lands. The rapid growth of pioneers is good for cash-strapped growers who need fast delivery from their crop.

There are almost as many names for the amaranth as there are species and hybrids. Here are a few: Umfino (Xhosa), Isheke (Zulu), Bitekuteku (Congo, Kinshasa Province), Efo, Tete (Nigeria), Alayyafu (Hausa), Grins and Hondi (Sierra Leone), Madze (Ghana) and Bonongwe (Malawi).

Amaranth is probably the best known, most widely eaten, leafy green vegetable in the African sub-region.

QUALITY FOOD, GOOD TASTE AND HEALTH BENEFITS

Described as having a taste varying from “something like spinach” to “similar to an artichoke” and a soft, palatable texture, it is no surprise that the crop is popular in Africa.

Perhaps, more importantly, it has a high percentage of quality protein (25% to 30%). This makes it a valuable addition to high carbohydrate diets founded on starchy root and grain crops.

In the production season, amaranth greens supply 25% of total protein to some African societies (Lost Crops of Africa Vol II). The greens contain vitamin C, iron and calcium and the leaves are rich in provitamin A (beta carotene).

Malnourished African children lacking dietary vitamin A suffer from a form of blindness, which is entirely preventable if amaranth is included in their diet. If for no other reason, this quality should make the amaranth a winning crop.

DESCRIPTION

An upright, branched, rough, herbaceous short-lived annual, the amaranth has a colour range that shifts through the spectrum from green to golden to bright red.
Height varies, according to species (from 60 cm to 2 m) and habitat conditions. (The shorter types are good for small gardens.)
Leaf sizes vary from 5 cm to 10 cm.
Dense clusters of small flowers form on terminal spikes or plumes.
The tiny seed (3 000 seeds: 1 g (Agricultural Research Council of South Africa)) is shiny and black to dark brown.

The amaranth has an erect growth form, reaching heights between 60 cm and 2 m. Oval shaped leaves provide a rich harvest for smallholder farmers and kitchen gardeners during the plant’s production season.

HABITAT RANGE AND PLANT REQUIREMENTS

LOCATION

The amaranth grows in moist, humid lowlands, dry savannah regions and highland areas across western, central, eastern and Southern Africa.
It is usually found at altitudes below 800 m above sea level (asl) but there are species that thrive at altitudes up to 2 000 m asl.

TEMPERATURE

These plants don’t like the cold. Plant growth stops when temperatures fall below 8°C, although some agronomists put this figure much higher. Again, it’s probably species dependent.
Temperatures from 16°C to 40°C are in the tolerance range.
Temperatures of between 16°C and 35°C are most favourable for germination.

WATER

Despite its adaptability, the amaranth needs water and is most suited to hot, moist tropical and temperate zones with high rainfall.
It can be cropped year round in the tropics.
Water needs are between 25 mm (1”) and 40 mm (1.5”) a week, so in drier regions the crop needs irrigation. The minimum daily requirement during the active growing season is 8 mm (0.3”).

SOIL

Light, sandy, well-drained, fertile loams are the ideal soils for amaranth, but pioneer plant species typically adapt to a wide range of soil types.
Soil pH should be between 5.5 and 7.5.
Low soil fertility can be corrected by working cattle, chicken or compost manure into the soil at the rate of 1 bucket/m² or applying mineral fertiliser at a rate of 1 teaspoon to 2 teaspoons every metre in the row.

Also read: Do it yourself: Making your own basic soil pH test

PLANTING

Aim for a warm, open site with full sun and well drained soils for the amaranth.
The tiny seed is difficult to sow evenly across the land. A 50 : 50 sand mixture makes it easier to get even dispersal.
A planting rate of 1 kg of seed/0.5 ha (2 lbs of seed/acre) produces so many seedlings that the crop remains productive even if there are big losses.
Broadcast seed onto a seedbed in loosened ground and cover lightly with soil (less than 1 cm) or sow it into shallow, grooved rows with the same light soil cover.
Some farmers sow seed into nursery beds and transplant at 3 to 4 weeks when the plant is 15 cm tall.
Twice daily watering is a must to keep the soil moist until emergence.
The tiny seed and the light soil cover means the crop is vulnerable during start-up.
A hard rain or poorly applied irrigation water can wash the seeds away.
A thin layer of grass mulch provides some protection but many growers prefer to sow into nursery beds transplanting when the danger is past, especially during the rainy season.
Recommended spacing is 30 cm between plants and 1 m to 1.5 m between rows.
A monthly top dressing of limestone ammonium nitrate (LAN) or well decomposed manure should provide the necessary plant feed.
Fertilising with Nitrogen (N) boosts leafy growth and yield, but the temptation to add N beyond the recommended rate will make soil toxic and cause plant dehydration and leaf-burn.
During early growth weeding is essential, but once the plant is 15 cm tall (6”) the leaf canopy will eliminate weeds by shading them out.

PRODUCTION HARVEST

Large-leaved varieties are suited to farmers who want to grow amaranth for greens (rather than grain).
The rapid-growth habit of the crop makes a first harvest possible 25 to 30 days after sowing.
After a further 3 weeks, the leaf harvests may begin with successive harvests taken every week or 2 weeks.
3 weeks after sowing, at transplanting or thinning, the young plant (leaves, stem and inflorescence) is edible.
A percentage of the crop is pulled up and marketed or taken to the farmer’s kitchen to provide food for the family.
If the grower intends to market young plants only the recommended plant population is 100 plants/m² to 200 plants/m². Yields may be between 1 kg/m² and 2.25 kg/m².
Leaf harvesting starts 3 to 4 weeks after transplant or 7 to 8 weeks after sowing.
For repetitive leaf harvesting, the recommended plant population is 20 plants/m² to 25 plants/m².
The first cut can yield between 1 kg/m² and 1.5 kg/m².
In 1 year, a square metre of land can provide 30 kg of marketable product, under a continuous cropping regime.
The harvesting method is to pick and cut leaves and lateral shoots, which acts to stimulate regrowth for further harvesting.
On a per-hectare basis, vegetable amaranth yields are generally in the range of 4 to 14 tons green weight, but yields up to 40 t/ha have been reported in trial conditions.

MARKETING

Amaranth greens are grown, harvested and marketed locally because of the perishable nature of the produce.
Bunches of cut leafy stalks stored in containers with 5 cm (2”) of water, in a cool place, will stay fresh for 5 days.

Also read:
Indigenous crop production: The versatile African eggplant
Indigenous crop production: How to grow African eggplant seedlings
Indigenous crop production: Preparing land for African eggplant and managing your crop
Indigenous crop production: An introduction to African nightshade

References:
Lost Crops of Africa Vol II Vegetables. National Academies Press 2006.
Food from the Veld – Edible Wild Plants of Southern Africa. Hallowes D., Young M.M., Fox F.W. 1982.
http://africanorphancrops.org/meet-the-crops
http://www.arc.agric.za/Indigenous-Crops.aspx