ECHOcommunity Conversations

Cover crop in Free State

#1

Does anyone have recommendations for cover crop and/or green manure to use in the Free State of South Africa?

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#2

Based on a period of time (2010-15) over which ECHO trialed legumes in South Africa, I can say that lablab, cowpea, and velvet bean grew well in Limpopo during the summer months. Lablab starts slow but once the vines are established they will produce more biomass than cowpea. Rongai and Highworth are the two main varieties you are likely to find from seed suppliers. Both grow well. Lablab is often referred to as dolichos bean. Cowpea establishes early, and there many varieties with variations in growth habit (prostrate for ground coverage versus more erect for more efficient harvesting) and time to maturity (earliest-maturing varieties may not produce as much biomass as later maturing varieties). Velvet bean is typically grown in more humid areas but it did surprisingly well in Limpopo. Horse gram (Macrotyloma uniflorum) also grew very well, producing a low, dense canopy; seed of this might not be as available in South Africa as lablab, cowpea and velvet bean. Vetch grew well as a winter legume.

You may already be aware of where to find seed. At the time, we were able to purchase 50 kg bags of lablab and cowpea from Agricol. Other sources I found online are McDonalds Seeds and Bulkseed.co.za-Farm Supply.

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#3

You may find this tool helpful -
https://www.echocommunity.org/tools/gmccselector

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#4

Thanks, Tim. I knew you’d have an answer. Further question: we’ve not started growing animals yet, so the cover crop I’m looking at is for weed suppression, moisture control and soil enrichment. I’m thinking of planting my cover crop around larger plants to accomplish this. Any further suggestions based on this? Thanks again.

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#5

Glad to be of help. If you are just looking for weed suppression and soil-related benefits, you have more options than if you are looking for those benefits plus a food/fodder source. From what I’ve observed, lablab and velvet bean vines are able to grow over the top of weeds and compete with them for light. Cowpea can do that to an extent but not as aggressively as lablab and velvet bean.

There are some tradeoffs with lablab and velvet bean. Lablab produces an edible bean (if you end up needing that) but the pods are susceptible to piercing insects, and lablab is slower to establish than velvet bean. Once lablab vines get established, they will form a thick canopy that shades out weeds, minimizes loss of soil moisture to evaporation, and enriches the soil with a lot of biomass. Without some initial weeding, though, lablab might be overcome early on. That was evidenced for us in a trial in which lablab was planted into maize at different times; when it was seeded at 0 and 2 weeks after maize, it grew fine, but 4 and 8 week plantings resulted in seedlings that remained stunted the entire season. That trait is actually a positive in terms of intercropping with cereals, giving time for the cereal to become established. Velvet bean needs more moisture to grow optimally, but it will establish sooner than lablab. Both vines will climb neighboring plants. That can be addressed through placement (with appropriate distance). We’ve also noted that lablab can be cut back and will regrow as long as it isn’t cut too close to the ground.

Another possibility is pigeon pea, which grows more like a shrub as opposed to a vine. Like lablab, it takes a while to get going, but once it does, it can form a tall canopy that shades out weeds underneath. There are early, mid, and late-maturing pigeon pea varieties. From what I’ve seen, the later maturing varieties produce the most biomass. In Limpopo, the late-maturing variety (Caqui) we trialed did not produce mature pods before frost, so that might be something to consider if you are wanting to be able to save seed. Sunnhemp was severely damaged by grasshoppers early on; the stems came back, but it did not perform quite as well for us as pigeon pea. Pigeon pea had more of a taproot while sunnhemp had more of a fibrous root system closer to the soil surface.

I’ve rambled on…hopefully this gives you some options and factors to consider.

Tim

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