Scientific Names: Desmodium intortum (Greenleaf desmodium) and Desmodium uncinatum (Silverleaf desmodium)
Desmodium / Napier Mixture
Desmodium is a trailing or climbing perennial legume with small leaves and deep roots which, in favorable conditions, form the very dense ground cover. It has a long growing season and grows well together with grasses, in a pure stand, as a cover crop together with grains, or under fruit trees, bananas or coffee. It is popular in cut-and-carry systems. It helps control soil erosion, fixes nitrogen in the soil thus improving fertility and increasing yields of crops while reducing the use of nitrogen fertilizers.
Desmodium is valued for its qualities as nutritious animal fodder. It also has a unique capacity to suppress Striga growth and reduce the seed bank in the soil. Planting rows of desmodium between rows of cereal crops can effectively reverse declining crop yields by controlling Striga and improving soil fertility, while at the same time providing farmers with a year-round supply of fodder. The crop is commonly used as a protein supplement in dairy cattle, with many farmers growing it to cut production costs. It is a good-quality supplementary forage with high protein content. It should be given in small quantities mixed with basal fodders
Silverleaf is a perennial, sprawling forage legume suited to under-sowing, intercropping, and improving stock exclusion areas. It has stems and leaves covered in dense hairs which make them stick to hands and clothing. It has green and white leaves which are light green underneath.
Greenleaf is a perennial, sprawling forage legume suited to under-sowing, intercropping, and improving stock exclusion areas as is one of the most important forage legumes. It is less tolerant of cool weather and light frosts. Its primary use is in forage production and its secondary uses are for nitrogen fixation and erosion control. It is leafier with reddish-brown to purplish spots on the upper surface of the leaves and reddish-brown stems.
Select Suitable Agro-ecological zones for growing desmodium.
- Silverleaf grows below 2200 masl, requires more than 900 mm annual rainfall, and is tolerant of cool weather and light frosts. Silverleaf should be grown on relatively fertile, well drained soils.
- Greenleaf grows below 2400 m altitude and requires more than 700 mm annual rainfall. Greenleaf should also be grown on fertile, well-drained soils, but needs careful grazing management for high productivity.
- Both varieties, however, are adapted to a wide range of soils from sands to clay loams and tolerate slight acidity but not salinity.
Seedbed preparation should be done well before the onset of rains. For the good establishment, the land should be plowed to an appropriate tilth. Use a tractor, ox plough or dip digging using a jembe to ensure deep tillage.
Seeds: Use 3–5 kg/ha (2 kg/acre) of desmodium seeds. Rhizobia inoculant needs to be added to the seeds in soils where desmodium has never been grown before. Sow seed immediately after mixing with an inoculant. If the bacteria is not available, mix the seeds with a handful of soil from another desmodium plot. Cuttings: Use freshly cut mature parts of desmodium vines.
Seeds: Planting from seeds Seeds can be sown either by drilling or by broadcasting. For drilling, make shallow furrows about 5cm deep spaced 30 cm apart. Cover the seed with 1 cm of soil and press softly. For broadcasting, spread the seed evenly over the seedbed. The nursery bed should be watered carefully and often. Shade may be provided but it should be removed soon after germination.
Planting from Vines/Cuttings Cuttings should be vines 60 cm long with soil still attached to the new roots. Make furrows 30 cm (or 50 cm) apart and 10 cm deep and plant the vines 30 cm apart. Bury 2 nodes leaving 1–2 nodes above the ground. When growing Desmodium between rows of Napier grass, plant the napier grass at a spacing of 1 m between plants and, wider than usual, with 2 m between rows. Make holes between rows of the newly planted Napier. Plant desmodium cuttings 30 cm apart, as you would with sweet potato vines
For Nursery bed (3 m x 3 m plot): Apply 500 g of phosphate fertilizer, TSP (45% P) or DAP (46% P, 18% N) to the plot before sowing and mix thoroughly with soil. Alternatively add 15 kg dry farmyard manure to the seedbed before planting. During planting, mix seed with 2 bags of TSP or 4 bags of single superphosphate (SSP) fertilizer. Farmers can also use 5–10 t/ha of well-decomposed FYM. Drill desmodium seed and fertilizer mixture in the planting furrows. Top dress with 2–4 bags of TSP or SSP fertilizer every year to maintain high yields of desmodium herbage and seed.
When desmodium is intercropped with maize it will provide N to the crop; inhibit the growth of Striga weed; reduce damage by the maize stem borer and control soil erosion. When grown together with Napier, desmodium adds nitrogen to the soil, benefiting the Napier and reducing the amount of nitrogen fertilizer required for top dressing.
Keep the stand free of weeds by using hoe or herbicide 2,4-D amine 72% at the rate of 2.5 litres per ha. Once desmodium has fully established, it forms a complete ground cover which smothers the weeds, thus reducing the labour requirement and cost of weeding the Napier plot.
Pests and Disease management
Spray against harmful pests such as aphids and diseases like anthracnose, especially when producing desmodium seed.Root-knot nematodes and leaf rust fungal diseases can do significant damage, but the plants do recover from both diseases, but with less foliage and seed.
Seed production is more successful when crops are grown on trellises, tall cereal crops or browse trees with harvests of up to 400 kg per ha possible. The simplest collection method is to strip ripe pods from the stalk, between thumb and forefinger. Pods are thoroughly dried, and seed is threshed out carefully using traditional mortar and pestle systems. It is normally possible to harvest and clean at least 1 kg per person/day. Greenleaf is exceptionally successful under perennial tree crops and forestry because of its shade tolerance. Store in a dry place after threshing to avoid rotting.
Subsequent cuttings should be at intervals of 6–8 weeks. Cut at no less 10cm above soil level. Cutting below 10cm can hinder regrowth and result in is destruction. For desmodium/napier intercrop, cut desmodium and napier together.
Desmodium is a good quality supplementary forage with high protein content. It should be fed in small quantities mixed with basal fodders. Three to six kilograms of green harvested desmodium should be fed to a cow in the place of one to two kilograms of the commercial concentrate. Excess desmodium may be cut, dried, and baled into hay and used as a protein supplement. It can also be mixed with grass when making hay. Cut and conserve as hay, whole or chopped. Desmodium can also be grown in association with tropical grasses such as Rhodes grass, Kikuyu grass, giant Setaria, etc. Where such is the case, it should not be grazed on before 16 weeks after sowing. Heavy or continuous grazing thereafter should also be avoided and rotational grazing should include rest periods of between 4 and 8 weeks.
The nutritional value of desmodium is normally high although tannin levels can exceed 3%. This can act as 'by-pass' protein increases the efficiency of digestion but also slows nitrogen cycling from leaf drop. The high tannin levels reduce palatability until stock acquires the taste for it. No toxicity has ever been recorded.
Silverleaf has 25.7% dry matter (DM) as fed, crude protein of 15.1% DM, calcium 8.5g/kg DM, phosphorus 2.2g/kg DM and metabolizable energy of 7.4mj/kg DM in ruminants. On the other hand, Greenleaf has 24.2% DM as fed, crude protein of 15.5% DM, calcium 10.2g/kg DM, phosphorus 3.1g/kg DM and metabolizable energy of 8.4mj/kg DM in ruminants.
Production (Yield) potential
An acre can produce 30–60 kg of seed. Dry matter Legume yields of 4-7 t/ha and legume/grass yields of 15 t/ha DM have been recorded, with increases of 90-150 kg/ha in soil nitrogen.