Increasing production of cover crops through silverleaf desmodium

By Bob Aston

Silverleaf desmodium are important to smallholder farmers as they help break hardpan and improve soil fertility by increasing nitrogen in the soil. Speaking while training members of Kahuhu Focal Area Development Committee (FADC) on October 29, 2015 at Kiboya village in Ol-Moran area of Laikipia West Sub County, Mr. Samuel Nyaga, Trainer of Trainers (TOT) on conservation agriculture said that cultivating the crop is important in soil conservation management.

He informed the twenty five (25)-member group that Silverleaf desmodium, scientifically known as Desmodium uncinatum is a trailing perennial legume that grows up to several meters long over surrounding vegetation. Its stems are cylindrical or angular, densely hairy, and may root at the node in wet conditions.

Mr. Nyaga training members of Kahuhu FADC

He noted that the plant has high nutritional value; the high tannin levels help to improve the efficiency of protein digestion and reduce palatability until stock acquire the taste for it.

He noted that it is best adapted to areas with average annual rainfall between about 1,000 and 1,600 mm, with warm season dominance.  

However, it can persist in areas with rainfall as low as 850 mm and as high as 2,400 mm.  Late season rainfall is essential for successful seed-set. It is a warm season plant but for cooler climates.

“Production of Silverleaf desmodium is a low cost method for enhancing both the quantity and quality of animal feeds. It is also drought tolerant and is adapted to a wide range of soils,” said Mr. Nyaga.

He said that it is less tolerant to low PH and will grow on a wide range of soil. It performs best in a well-prepared cultivated seedbed, but will establish on roughly cultivated land.

Farmers either can practice pure stands or mixed pasture with grasses like Kikuyu, Rhodes, or Seteria. Legumes like Glycine or Siratro also make good companion species.

Sowing is through use of a drill, ground broadcasting, aerial seeding, or sod seeding. Some seed cover after sowing is desirable. It should be sown in months when the probability of frost is low, to give as long a period as possible for establishment prior to onset of the next season's frosts.

Uses of Silverleaf desmodium

 Some uses of Silverleaf desmodium include long-term pastures although it rarely persists permanently, used in irrigated pastures, for conservation as hay and silage and for cut-and-carry systems.

Other uses include cover crop where the abundant leaf fall and slow decomposition result in a deep duff layer under the plants and it is also used in Push-Pull technology for control of stalk borers in maize and sorghum where desmodium is used as repellant to the pest.

Desmodium intercropped with maize in Push-Pull Technology. Photo FAO-Kenya

“Silverleaf desmodium is a nitrogen-fixing legume that improves the soil nutrient status and can provide nitrogen to neighbouring crops. Nitrogen fixation through inoculating seeds with special desmodium inoculant is recommended,” said Mr. Nyaga.

Management of Silverleaf desmodium

Mr. Nyaga noted that mature plants cannot tolerate constant heavy grazing or frequent heavy defoliation; reduction of dense stands is through scattering of small individual plants. Cutting should be in such a way that should allow regrowth.

Flowering commences in mid-April. Crops can be direct headed or mowed when fifty percent of the seed is ripe. The crop requires at least moderate levels of fertility. Application of phosphorous, Sulphur, and potassium is equally important.

Pod segments adhere to animal coats and clothing.  Trailing stems root at the nodes in moist soils.  However, it will only spread into suitably fertile soils. Once the crop establishes ground cover, no weeding is required.

“The plant is occasionally affected by legume little leaf disease. It is also susceptible to root-eating weevil larvae,” said Mr. Nyaga.

Food and Agriculture Organization of the United Nations (FAO) has collaborated with Laikipia County Government to implement FA0-Institutional Procurement Programme (IPP) and Conservation Agriculture/Good Agricultural Practices (GAP) project. The project aims to ensure sustainable production and environmental protection in conservation agriculture.