Farmers have turned to Tanzanian miracle rocks that have tripled their yields.
Smallholder bean farmers in Western Kenya have seen their bean harvests increase by 200 percent and their maize production increase from two tonnes per hectare every season to five tonnes per ha/season, thanks to the addition of 60 kg per hectare of phosphate rocks mined in Tanzania.
Up to 80 per cent of Western Kenya’s soils are low on phosphorus. Falling soil phosphorus levels are a majour threat to food security in Africa. Between 1961 and 1998, the continent’s rate of phosphorus loss was estimated to have tripled mainly because of continuous farming without refreshing the soil with new nutrients. According to a Replenishing Soil Fertility in Africa report this has left over 60 per cent of soils being phosphorus-deficient.
According to Dr. George Odhiambo an agronomist at ICRAF, phosphorus helps to make food for plants and in their development. “A lack of phosphorus slows down plant growth,” he explained
Before he started using Minjingu Phosphate Rock (MPR) which is gotten from Tanzania and is made from the same mineral that our teeth and bones are from, Jane Namano, a mixed farmer in Kakamega recalled that her harvests were falling after each growing season with each one being worse than the last.
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In 2018, Jane attended a farmer baraza where an extension officer introduced the benefits of using Minjingu Phosphate Rock (MPR) from Tanzania. *It seemed promising so I decided to buy some and apply it on part of my farm. I mixed the phosphate rock into the soil before planting,” she explained.
The results spoke for themselves. Within two planting seasons, the yield of her maize and beans, which she planted on two hectares, had increased by 200 percent. “My maize grew taller, while the bean pods were fuller. I was pleasantly surprised by the difference MPR made,” she said.
According to agronomist Odhiambo, “Phosphate rock, unlike Triple Superphosphate (TSP), which many farmers choose, is cheap and readily available within East Africa. Unlike most TSP, which is imported from Morocco, phosphate rock is perfect for use in acidic soils. This makes it ideal for many African farmers. “
MPR is applied directly or in combination with soluble fertilisers like TSP, organic matter, or compost to increase its ability to be absorbed by the soil.
In Kenya phosphate fertilisers can be bought from Minjingu Mines & Fertilizer as rock phosphate powder, Qualitas Company as powder rock phosphate, Safari Chemicals as organic hyperphosphate, and Desertcart Kenya which imports various phosphate fertilisers.
Each variant of phosphate fertilisers costs between Sh1,500-Sh4,750 per 50 kg bag.
Other low-cost methods of adding phosphorus to your farm include:
Intercropping maize with Mexican sunflower or Tithonia and Sesbania fodder shrubs. Crops growing on farmer soils with these nutrient banks report up to 30 per cent higher phosphorus uptake.
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Ash-enriched compost manure is another great option. Wood ash contains phosphorus that unlocks nutrients in compost that crops can use. A study conducted in Nakuru found that maize yields jumped 40 per cent when ash was added to soils.
Lastly, leaving crop waste, such as maize stalks, to rot in fields after harvesting recycles phosphorus. This farming method, called crop residue retention, improves low-phosphorus soils in which crops struggle to grow to optimal phosphorus and healthy soils in two seasons.
Photo Courtesy: Minjingu mines & fertilizer Kenya store