July 24, 2018

Blog: Let the bund training begin

Blog: Let the bund training begin


Two weeks ago, I was in the Dodoma region to train farmers how to dig soil bunds to prevent soil erosion and improve water availability for plants. I made a short summary of the findings of the visit to Pembamoto which is located about an hour drive from Kabaigwe, which is about two hours from Dodoma City.

Francesco and I gave a training to 10 fundis on laying out the bunds. Fundis are local technicians from Pembamoto. We trained them on how to use a spirit level instrument (plumb rule) to properly place them on the contour lines.

A normal bund has a diameter of 5 meter and they are spaced 5 meters apart. This is the excavation part of the bund. Since the soil is placed around this, the actual size of the bunds are 7 meters (excavation + soil bund) and spacing 3 meters. Like this:

The fundis understood the instruments quite quickly and managed to properly position the bunds.

We also trained them (and actually that is the most important part) how to deal with exceptions: e.g. when there is a gully at the place where you want to dig a bund. Sometimes you need to place them a bit closer to each other, make them a bit smaller/bigger or skip a bund completely. They also understood that fairly quickly, although checking will be important during the first phase.

The next day we got 20 farmers to actually practice the whole workflow: fundis laying out the bunds, famers digging them, fundis checking on the quality. This went smoothly too!

Soil testing

During our visit, we also did some soil testing: how quickly does the water infiltrate? The results are good: not too fast and not too slow!

Fun fact: in some places you can clearly see a crust on the soil, like this:

The test showed that the infiltration rate (how quickly does the water sinks into the soil?) on this crust is about 10x slower than when the crust (few cm’s) was removed. This clearly shows that bunds can greatly improve water availability for plants.

We aren’t sure however that there are enough seeds present in the soil. Since erosion has been taking place for a while and even after the good rains of last season hardly any vegetation returned. We therefore took some soil samples which are now placed at LEAD’s office (sorry Lucy for messing up your office!). Within a few weeks we hopefully see some seeds sprout. If this doesn’t happen we maybe have to do some re-seeding.

Exploring the area

Francesco and I continued to explore the area to determine where we could do bunds and where not. Most of the area around Pembamoto is agricultural land (and suitable for ‘Kisiki hai’: our other re-greening technique we use in Tanzania). For the bunds we are focusing on communal land. It turned out that quite a large part of the area we had in mind is actually not suitable for bunds: it’s either too rocky (hard to dig) or has too many gullies. See the photo below: the gullies are spaced so closely to each other that you can’t dig bunds in between.

In total we estimate that about 15% of the 400 ha area is suitable for bunds (to be confirmed after we processed the detailed aerial mapping we did with the drone). For other areas you could do something else. E.g. stone lines (like in Kenya) or ‘vegetative lines’ like they use in the area to ‘fence off’ agricultural plots:

The plants (Agave/Sisal or Euphorbia) hold the soil and break the force of water. Sediments can build up behind them as you can clearly see on the photo below:

Yes.. Francesco and Sylvester (LEAD Foundation) are about the same length.

The plants have trapped about a meter of sediment. If you would construct multiple lines – like this – parallel to the contours (just like stone lines) you can restore the degraded lands where there are a lot of gullies. Since they use them as hedges, you can find a lot of these plants in this area and you can easily pull out young sprouts and plant them:

Community meeting

The first discussions with the community in Pembamoto were promising. They see this as a good option to restore the area. This is something we have to explore further (Will it work? How quickly do they grow? Won’t they be eaten? Etc. etc.)

Something we have to check and discuss with the community is the extent to which we want to do interventions (bunds or something else). Since most of the lands are agricultural, there is limited land available for grazing. We can’t take away all that land, because then the community’s cattle can’t graze anymore (or use these areas to walk to other grazing areas). This is something we have to properly check and confirm. We need to have a more in depth look at the area (after mapping etc.) and get back to this. For the first stage this won’t be a problem, but for scaling we need to think about this and probably have some more community meetings.

As you can read, it was a very productive week. Keep you posted!


Chief Technology Officer