Notes to broadcasters
Karatu is one of five districts in the Arusha region of northern Tanzania and is about 150 kilometres west of Arusha town. Agriculture is the main livelihood for households in the area, who grow staples like maize, pigeon pea, cowpeas, cassava, potatoes, sweet potatoes, black beans, beans, and pumpkins. Karatu’s clay soils were traditionally fertile, but in recent years have become degraded. Because Karatu’s terrain is hilly, when it rains, water runoff carries away the fertile topsoil and leaves gullies on farms. Farming practices such as growing crops continuously without replenishing the soil with manure to make it fertile made the soil poor, and intensive intercropping have also contributed to soil degradation in Karatu.
This script shows how soil erosion and degradation has affected soil fertility and crop yields for small-scale farming households in Karatu. An expert on soil fertility and land restoration describe the causes of soil erosion and degradation in the area. He will also discuss the agronomic training they are providing to small-scale farmers to help them address soil erosion and rejuvenate their low-yielding soils. The expert will also discuss other agricultural practices that can help small-scale farmers there to increase their incomes, including poultry rearing.
To produce a similar script for a program to educate small-scale farmers on how to address soil erosion and degradation, interview a land restoration expert and small-scale farmers affected by these problems. The expert can provide the technical knowledge needed and farmers can share their views before and after adopting the practices the expert proposes.
If you choose to use this radio script as part of your farming program, you could use voice actors to represent the people interviewed. If you do so, please inform the radio audience at the start of the program that those are voices of actors and not the real interviewees.
Here are some questions you can ask the subject matter expert and small scale farmers:
- What are the natural and human causes of soil erosion and degradation in this region?
- How has soil erosion and degradation affected agricultural production and livelihoods in this region?
- What land restoration practices have you introduced to farmers to help them?
- What impact has these land restoration practices had on crop yields?
- What crops do small-scale farmers grow in this district?
- How has soil erosion and degradation affected your crop yields and income?
- After adopting improved agricultural and land restoration practices, have your crop yields and incomes changed?
Duration of the script, with intro and extro: 20 minutes.
To help in our discussion and answer questions, we have with us Eliud Letungaa, an expert in land restoration involved in a project on regenerative agriculture in Karatu district run by MVIWA Arusha, a farmer-based organization.
Please give us a brief context of how soil erosion and degradation have affected small-scale farming in Karatu district.
It’s important to note that runoff water can be useful for improving vegetation cover if managed well. For example, creating contours or terraces or other structures that will hold or harvest can facilitate tree growth and reducing the need for frequent irrigation. Those are some of the factors that made us introduce the project here.
If farmers can grow multiple crops and keep livestock, they will create an ecosystem where crop residues are used as fodder and livestock manure is used as a source of crop nutrients.
We also recommended that farmers plant indigenous trees like Acacias, especially Acacia nilotica that act as a windbreak and prevent soil erosion. Acacia nilotica also has pods that farmers can feed their goats and it’s generally a good tree for the environment. For example, it fixes nitrogen in the soil, and protects cropland from fire and wind, as well as producing roots which help hold the soil.
We encourage farmers to also plant exotic trees like Grevillea and Acrocarpus fraxinifolius that are fast-growing, multipurpose trees that can be harvested for timber or firewood. Acrocarpus fraxinifolius is best grown in field boundaries where it acts as a windbreak. Grevillea robusta is one of the best agroforestry trees. It can be planted on field boundaries for demarcation or as a windbreak. Supplemented with elephant grass which anchors the soil, it also strengthens ridges or contours and improves the soil when its leaves fall and add to the soil organic matter.
Banana farming is integrated with cover crops like lablab and mucuna species, also called velvet bean. These legumes are good at adding nitrogen to the soil and combating soil erosion. Also, we emphasize agroforestry and agroecology practices because these approaches build soil resilience to different forms of erosions.
All these practices have boosted crop yields. We’ve also introduced and strengthened poultry keeping as a source of income and nutrition stability to the community. This helps farmers produce eggs and chickens for sale and get much-needed manure for their degraded farms.
And I’ve seen results! Last year, my farm wasn’t destroyed by runoff from the rains—and not just me but my fellow farmers who adopted similar practices. Other farmers are coming to ask us for advice on carrying out similar practices to prevent soil erosion on their farms. I anticipate that the quarter-acre that was destroyed will be rehabilitated and I will be able to farm on it again next year.
Being legumes, these plants also make our farms fertile by fixing nitrogen in the soil. They also don’t interfere with the pigeon peas and other crops I grow. And when those legume trees shed their leaves, we leave them on the ground and they add humus and enrich the soil with different materials and make it fertile.
Training from MVIWA Arusha also helped us learn the importance of mulching for soil fertility and moisture conservation. After harvests, we used to bulk the residues from dry maize and the pea crop and feed it to our livestock. But now after harvest, we spread the drying crop residues all over the land as mulch to cover the soil and replenish it with organic matter to make it fertile. But if it is necessary to use the crop residues as fodder, we make sure that we return the livestock manure back to the farm.
Gitu, what advice do you give to farmers here in Karatu who are struggling with soil erosion and land degradation based on what you’ve learned from MVIWA Arusha?
Soil erosion can also be minimized by planting trees or cover vegetation on gullies. The vegetation helps trap soil that is carried by the water runoff, and eventually the gullies fill up and the land becomes level. Though my farm is on a slope and in the past I’ve experienced lots of flooding, I now plough it in a way that reduces the speed of water runoff and spreads the water over the farm so that no gullies form and there is minimal damage.
We also urge farmers to maintain permanent soil cover on their land by spreading residues from harvested crop residue to form a mulch instead of feeding them to livestock. That shields the soil from the harsh sun. And when it’s ploughing time, the mulch is worked into the soil and becomes manure that makes the soil fertile. Cover crops also help slow water runoff and minimize land destruction.
In Karatu, we plant Mucuna pruriens and lablab as well as Grevillea robusta and Acacia nilotica to help trap the soil, fill the gullies, and reduce runoff. Mucuna is upupu in Swahili and lablab is fiwi or ngwara, while Grevillea is mgrivea and Acacia nilotica is mgunga. The two legume cover crops also suppress the stubborn purple nutsedge weed and couch grass, commonly known as sangari in Swahili. Also, more training is needed for farmers who are skeptical that leguminous trees like sesbania can improve soil fertility on their farms.
And if you later top dress with urea or NPK fertilizer when the maize has six leaves or is at knee level, that helps suppress striga weed and increases the possibility of getting high yields. By following these instructions, you can get yields of 28 to 30 bags of maize per acre. In our five acres 15 years ago, we harvested 50 bags of maize. Today on those five acres, after the training, we get 100 or more bags of maize by planting the right way. For beans we get eight to 10 bags per acre, depending on the variety. For yellow soya, we used to get three bags, but today we harvest five bags per acre. So all those MVIWA-Arusha trainings have helped us address the gulley problems and improve soil fertility. And we’ve seen great and positive changes.
HOST: Dear listener, before we conclude, let’s review what we learned in this program.
If uncontrolled, water runoff can form gullies that make farming challenging.
But gullies can be filled by planting leguminous trees or cover crops or other vegetation that slow the momentum of the runoff and trap the soil.
Soil infertility can be addressed by planting leguminous trees or cover crops.
Residues from harvested crops should be left on farm as mulch to cover the soil and make it fertile and also reduce erosion.
Ensure that soil on hills has a permanent soil cover.
Contributed by: James Karuga, agricultural journalist, Kenya
Reviewed by: Eliud M. A. Letungaa. Field office in agriculture and livestock, Mtandao wa Vikundi vya Wakulima na wafugaji Mkoa wa Arusha (MVIWAARUSHA).
This resource is undertaken with the financial support of the Biovision Foundation.