Growing Desmodium, A Super Fodder Crop

Desmodium is a legume that is commonly used as a protein supplement in dairy cattle, with many farmers growing it to cut production costs.

The crop has numerous varieties but the most common are greenleaf and silverleaf. The legume can be intercropped with napier grass and maize to help control stemborer and weeds such as striga under the ‘push and pull’ technology.

Moreover, it helps control soil erosion, fix nitrogen in the soil improving fertility and increase yields of intercrops while reducing use of nitrogen fertilisers.

Greenleaf can be grown with companion grasses such as napier, Kikuyu and Boma Rhodes. However, the legume can become invasive, therefore, it is better grown and managed as a pure stand.

Morphologically, the stems of greenleaf are green or sometimes red, with many trifoliate leaves.
The variety is leafier than silverleaf with ovate and reddish-brown to purple coloured leaflets.

The flowers are deep lilac to deep pink in colour while the pods are narrow, containing kidney-shaped seeds that stick strongly to hair or clothing.

Silverleaf, on the other hand, has cylindrical or angular densely hairy stems, with ovate and broad, dark green leaflets but silvery midrib at the upper side and whitish hairs on the lower side.

Its flowers are pink to bluish as they mature, while the seeds are triangle or oval shaped and olive-green in colour.

Greenleaf grows well in cool seasons with adequate moisture but is more susceptible to drought but has better tolerance to flooding and waterlogging whereas silverleaf is a warm season legume.

The legumes are adapted to a wide range of soils from sands to clay loams and tolerate slight acidity but not salinity.

Desmodium commonly takes longer to establish than most tropical legumes. In fact, there are cases where farmers have planted seeds, but they fail to grow or attain poor rate of germination.

The seeds, which are very small and relatively expensive, can be acquired from any well-stocked agrovet near you.

They are best sown in a weed-free, well-prepared nursery seedbed with fine-textured soil. A 3m by 3m seedbed requires about 100g of seeds or simply about 2kg of seed per acre.

Apply phosphate fertilisers

The legume establishes best with beneficial rhizobia bacteria, which live in their roots and fix nitrogen from the air and avail it freely to the growing plants.

If the bacteria is not available, mix the seeds with a handful of soil from another desmodium plot.

The best time to plant is at the onset of rains, by sowing the seeds either by drilling or broadcasting immediately after adding the inoculant.

Drill the seeds into shallow furrows spaced a foot apart then cover with little soil and press lightly. For broadcasting, spread the seed evenly over the seedbed. In both cases, water carefully and regularly.

The legume can also be established cheaply from cuttings. Though bulky, cuttings should be freshly cut mature vines 2 feet long with soil still attached to the new root hairs. Make furrows a foot apart and 10cm deep and plant a foot apart.

Apply phosphate fertilisers such as TSP or DAP before sowing and mix thoroughly with soil. Farmyard manure may also be used as an alternative.

Once fully established, desmodium forms a complete ground cover that smothers weeds. Spray against harmful pests such as aphids and diseases like anthracnose.

For yields, a 12-19 t/ha/year has been reported for greenleaf and 7-9 t/ha/year for silverleaf. Harvesting starts at four months, and is done by cutting 10cm or higher above soil.

Spread in the sun for a few hours to wilt before feeding. Three to six kilos of green harvested desmodium should be fed to a cow in the place of 1 to 2kg of commercial concentrate. Excess desmodium can be dried and baled into hay.

Nutritionally, desmodium has high crude protein levels and is rich in minerals and vitamins.

Silverleaf has 25.7 per cent dry matter (DM) as fed, crude protein of 15.1 per cent DM, calcium 8.5 g/kg DM, phosphorus 2.2 g/kg DM and metabolisable energy of 7.4 MJ/kg DM in ruminants.

On the other hand, greenleaf has 24.2 per cent DM as fed, CP 15.5 per cent DM, Calcium 10.2 g/kg DM, phosphorus 3.1 g/kg DM and ME of 8.4 MJ/kg DM in ruminants.

Advantages

High quality, protein rich forage; can be grown between or under other crops – as it fxes nitrogen it increases yields and reduces the need for nitrogen fertilizer.

Disadvantages

1. Seed is expensive and very small;
2. Needs rhizobium inoculant;
3. In very high rainfall areas (more than 1500 mm per year) it suffers from pests and diseases;
4. Does not tolerate drought;
5. May need irrigation in lower rainfall areas;
6. Does not tolerate alkaline soils.