Knowledge is power busTIng soil myths in Tanzania

Farmers know that soil is a precious commodity. But in Babati district, northern Tanzania, a long held belief that mineral fertiliser spoils soils is preventing them from making informed decisions on how best to keep their soil healthy and increase their yields.

Researchers from the International Center for Tropical Agriculture (CIAT) and the Selian Agriculture Research Institute (SARI) are investigating best-bet fertiliser options and agronomic practices for maize in the region as part of the USAID-funded Africa RISING. Their work is challenging local beliefs and changing attitudes.

Maize is one of the most important crops for food security and livelihoods in Tanzania. Yet, while many farmers grow improved varieties, yields are far lower than their potential. Most farmers don't use mineral fertiliser and those that do don't apply enough to make an impact. More farmers use organic fertiliser such as manure but supplies are limited.

Wema Ako, a farmer from Long, a small village in the peaks of the East African Rift Valley Highlands, was brought up to believe mineral fertiliser is bad. He doesn't know where the belief came from but his father, from whom Wema inherited land, refused to use industrial fertiliser.

In fact, the belief is so old that only older generations remember how it started. Gabriel Leonse (59) from Seloto village remembers a visit from an extension worker more than 40 years ago.

"In 1974 an expert came to tell us about field management and fertiliser. They brought ammonium sulphate and taught us to apply it around the plant stem," Gabriel recalls. "It burnt the leaves and the following season the harvest was lower than before it was applied."

"After that, many believed fertiliser was bad for the soil. The extension worker never came back."

Soil science and fertilisers have come a long way since 1974. Today, after carrying out soil tests, researchers know that ammonium sulphate is not appropriate for soils in Babati because it increases soil acidity. Yet it remains the recommended fertiliser for the entire country.

"It's not surprising farmers here don't use fertiliser. The type of fertiliser and application method recommended were incorrect. And since no one ever returned to give them new and better advice, they don't know the options available or if they can afford it," says CIAT soil scientist Isaac Savini.

Two years ago Isaac, along with partners from SARI, started working with farmers in Babati to test the suitability of different fertilisers on maize crops. It was the first time anyone had advised farmers about fertiliser since 1974.

The aim of the Africa RISING project is to discover optimal - and affordable - organic and mineral fertiliser combinations coupled with the most suitable maize varieties and most appropriate agronomic practices.

Each season a group of volunteer farmers agree to use different fertiliser combinations on a section of their land. And at each harvest Isaac returns to collect samples for comparison.

He tests the soil and the weight, number of cobs and biomass of the maize.

"At first it wasn't easy to find farmers who were willing to work with us," said Isaac. "But now they have seen the results of the trials we are turning farmers away."

Rita Matias was nominated by her community to take part in the research.

"I've always used manure to fertilise my soil but I had to rotate it because there was never enough to go round," said Rita. "I never used mineral fertiliser because I didn't have any knowledge about it."

Since she has been using mineral fertiliser, Rita has noticed a big difference in her yields and has increased her income by 50 per cent or more, depending on the market.

"It is more work to use fertiliser," said Rita, referring to weeding, correct spacing, pest and disease control and other agronomic practices needed to get the best out of her investment. "But it's worth it."

Rita is now training others on how to use fertiliser. "Neighbours see my field and ask me about it. By teaching others we are reducing the numbers of people who think it is bad for the soil. Now they can use it correctly."

Wema is also taking part in the trials. At harvest time it's easy to see which crop was fertilised and which wasn't. The cobs from fertilised plants are double the size of those that weren't.

The most promising combination of organic and mineral fertiliser is producing on-farm yields of up to six tons of maize grain per hectare. The regional average is less than one ton per hectare.

Despite the presence of researchers and the results of the trials, some farmers are still not convinced. Joseph Teodule (79) states he will never use industrial fertilisers. "I know fertiliser could give me higher yields but from my heart, I am not willing," said Joseph.

"But at least," says Isaac, "he is now making that decision from a position of knowledge. That is what we want."

Education is only the first step in enabling farmers to make informed decisions about fertiliser.

Isaac is working with Corneleus Yangole, a researcher from SARI. "Once we have assessed the performance of each option we will carry out an economic analysis so that our final recommendations are based on the best and most financially affordable options," said Corneleus. "We can make all the recommendations we want, but if they are beyond a farmers financial means they are useless."

Researchers have one more season of trials to go before they make their final analysis.

SARI will use the recommendations to work with agro dealers to ensure suitable maize varieties and inputs are available locally, as well as work with government to support farmer friendly policies.

The Africa Research in Sustainable Intensification for the Next Generation (Africa RISING) programme is part of the U.S. governments Feed the Future initiative, which is split into three regional projects. Research conducted by CIAT and SARI is part of the Sustainable Intensification of Key Farming Systems in East and Southern Africa project led by the International Institute of Tropical Agriculture (IITA).

The UN has declared 2015 as the International Year of Soils to raise awareness of the urgent need to protect the hand that feeds and waters us - our soils. Find out how CIAT's global soils team of scientists, ecologists and anthropologists are working to protect this vital resource. View our links below:

Photo credit: Stephanie Malyon / CIAT

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Stephanie Malyon


Stephanie Malyon / CIAT

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