Fertilizers may not help poorest African farmers

Sep 24, 2009 By Krishna Ramanujan
Recent studies looked at soil fertility data for maize plots -- some that had been cultivated for 100 years -- on 260 farms in western Kenya such as this one.

(PhysOrg.com) -- Researchers have linked poverty in sub-Saharan Africa with poor soil health, but two new Cornell studies find that the recommended practice of applying more fertilizer may not help the poorest farmers.

Two new studies by Chris Barrett, the Steven B. and Janice G. Ashley Professor of Applied Economics and Management at Cornell, and Paswel Marenya, Ph.D. '08, a lecturer at the University of Nairobi, find flaws in the fertilizer-promotion strategy used by dozens of African countries to improve soil health, crop yields and the wealth of poor farmers. Forty African heads of state had devised plans in 2006 to help farmers in sub-Saharan Africa -- one of the poorest regions of the world where soils are often too degraded to reliably grow crops -- get better access to soil-enhancing fertilizers by improving roads, increasing access to seasonal credit and improving farmer education on fertilizer use.

"If soils are too degraded, fertilizers don't respond well," said Barrett. "These results challenge basic assumptions behind efforts to promote fertilizer use and distribution as a key element of poverty reduction strategies in rural Africa."

The first study, published online in the American Journal of Agricultural Economics (and in print in November), looked at soil fertility data for maize plots -- some that had been cultivated for 100 years -- on 260 farms in western Kenya. The study found that fertilizers' effects on crop yields are far greater when applied to healthy soils with higher levels of soil carbon and than when applied to degraded soils with low soil carbon. The degraded soils usually were the result of repeated plantings without breaks. The authors also reported that poorer farmers most commonly cultivate the most degraded soils, which means that fertilizer policies aimed at helping the poor may actually reinforce income inequalities.

The paper noted that without adequate soil carbon and organic matter, plants absorb fewer of the nutrients in fertilizers. The study recommends greater emphasis on integrating organic matter, such as manure from livestock or post-harvest crop waste, to raise levels and make nutrients from fertilizers more available to plants.

The second study, published online and in the September print issue of the journal Agricultural Economics, reports that Kenyan farmers find fertilizers expensive and recognize that they do not increase yields in degraded soils. Therefore, farmers on low-carbon soils use less than half as much fertilizer as neighbors cultivating better soils. In spite of government efforts to educate farmers and make fertilizers more available and affordable, farmers working with degraded soils have failed to respond to such programs or to increase fertilizer use, while farmers who cultivate good soils reap further benefits from cheaper fertilizers.

" promotion policy doesn't help the poorest farmers very much," said Barrett.

The studies were funded by the Rockefeller Foundation, the U.S. Agency for International Development and the National Science Foundation.

Provided by Cornell University (news : web)

Explore further: New water balance calculation for the Dead Sea

add to favorites email to friend print save as pdf

Related Stories

No-tillage plus

Jul 28, 2008

Tropical soils often behave differently than temperate soils when being farmed. In tropical regions, soils lose nutrients quickly when cultivated. With food shortages looming and soil quality declining rapidly, new farming ...

Measuring calcium in serpentine soils

Aug 19, 2008

Serpentine soils contain highly variable amounts of calcium, making them marginal lands for farming. Successful management of serpentine soils requires accurate measurement of the calcium they hold. Research published this ...

Nitrogen applied

Oct 01, 2008

Combating soil erosion is a primary concern for agricultural producers in the United States, and many have incorporated conservation tillage systems in their effort to maintain a profitable crop output.

Improving swine waste fertilizer

Jul 08, 2008

Swine production generates large amounts of waste. While this waste contains nutrients that may serve as fertilizer when applied to agricultural fields, the ratio of nutrients in the waste is different than what a crop requires.

Recommended for you

EU sets new energy savings target at 30%

6 hours ago

After months of tough negotiations, the European Commission recommended Wednesday a new energy savings target of 30 percent so as to combat climate change and ensure self-sufficiency.

User comments : 0