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Our soils are dying, and more fertiliser is not the answer

Friday April 25 2014

Soil acidity control: A tractor pulled machine sprinkles lime at Kapsuswa farm in Uasin Gishu County to reduce the soil acidity before planting maize on April 25, 2014. Charles Boit, Director at the farm, said the acidity is due to usage of DAP fertilizer all seasons and analysis on the farm indicated a PH of 5.5-5.8 which has to be corrected to the recommended PH of 6.5. PHOTO | JARED NYATAYA

Soil acidity control: A tractor pulled machine sprinkles lime at Kapsuswa farm in Uasin Gishu County to reduce the soil acidity before planting maize on April 25, 2014. PHOTO | JARED NYATAYA  

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Kenya’s soils are in the Intensive Care Unit (ICU), and urgent action is needed to breathe new life into the seriously malnourished earth.

According University of Nairobi soil scientist Nancy Karanja, the first line medicine is not ready availability of the much-hyped subsidised chemical fertilisers, which farmers in most parts of the country are forever whining about; it is harvesting mountains of biodegradable waste that despoil Kenya’s urban landscape and returning them to the farms.

This, she says, can be done through mobilisation of citizens particularly in the urban centres for monthly clean-up exercises.

The biodegradable materials can then be composited and packaged as organic fertiliser and either sold or given freely to farmers in rural areas, Prof Karanja says.

Her colleague, Dr Richard Onwonga, feels this is the only way nutrients in edible products from rural to urban areas can find their way back to farms.



Seeds of Gold interviewed the top scientists in the wake of the February 18 high-profile launch of recommended fertilisers for Kenya’s different agro-ecological zones by President Kenyatta and his deputy, Mr William Ruto, at the Egerton University in Njoro, Nakuru County.

Karanja and Onwonga, both soil scientists at the Land Resource Management and Agricultural Technology Department of the University of Nairobi’s Upper Kabete Campus, used all manner of adjectives to drive home the message about the need not only to focus on chemical fertilisers, but also organic fertilisers. The latter contribute to organic matter to the soil.

“Ninety nine per cent of the soils in Kenya — and in tropical and sub-Saharan Africa — are in one way or the other sick. They have no carbon,” Karanja said of the soils she described as ‘sick and tired’: “Soil fertility is humus. If you have no humus in the soil — (organic carbon in scientific parlance) — even if you pump in DAP and lime, that will only be a temporary remedy.”

Onwonga, a specialist in organic farming, noted that infertile soils were not just the bane of conventional farmers, but also of poor farmers with pretensions to organic farming. They practise organic agriculture by neglect in the sense that, “they just don’t apply anything.”

So, what is the problem? Seeds of Gold asked the dons. It is two-fold: on one hand is conventional agriculture practice, which heavily relies on chemical fertilisers. And, on the other, is continuous mining of organic matter by crops on small-holder, subsistence plots, which, due to continuous fragmentation attributable to population pressure, can no longer be regenerated through traditional crop rotation.

“Where the inorganic fertilisers have been continuously used, the soils don’t have enough organic matter,” Onwonga said, adding that such soils were prone to erosion. The result is that the top soil is close to dead, Karanja asserts.

The upshot is that unless drastic measures are taken to restore, maintain and enhance soil fertility, both in traditional and conventional agriculture, crop production can only decline. At the moment, the task of maintaining and enhancing soil health rests with the scientists, since, as Seeds of Gold learned, the government has no policy on soil conservation.

The Principal Secretary in the State Department of Agriculture of the Ministry of Agriculture, Livestock and Fisheries, Mrs Sicily Kariuki, said in an e-mail interview: “We do not have a soil conservation policy. However, soil conservation issues are mainstreamed into other agricultural policies as this is one of the strategies for increasing agricultural productivity.” (See Q & A interview)

While acknowledging conservation agriculture as key to “promoting land regeneration and sustainable land use” and that it is essential for maintaining minerals within the soil, stopping soil erosion and stopping water loss from occurring within the soil, the PS also recognised intercropping and/or rotation as a means of building “soil infrastructure” and allowing for an extensive build-up of rooting zones which allow better water infiltration.

“Plans are underway to allocate resources to develop a soil fertility and fertiliser policy. Soil conservation is one of the interventions for improving and sustaining soil fertility,” Kariuki said.

Vis-à-vis such a vague policy framework, the burden of disseminating viable soil enhancement and maintenance practices to farmers lies with the scientific research community which, on the other hand, is badly constrained by a limping extension system. The PS says the ministry has an “inadequate number of extension offices”.

Kariuki and the dons the Seeds of Gold interviewed share the view that fertiliser use in Kenya, as in the rest of sub-Saharan Africa, is very low. They differ, however, on whether increased fertiliser use is the answer to declining food production.

According to the PS, “increased use of fertiliser is a key factor. This is in line with the Abuja Declaration of 2006 that avers; ‘Fertiliser is crucial for achieving an African Green Revolution in the face of a rapidly rising population and declining soil fertility”.

Kariuki says the ministry has made recommendations on the types of fertilisers for the different zones, referring to the Egerton event in February.


But there is a problem. The PS’s reference to the Green Revolution means that the Kilimo House technocrats and scientists in university laboratories could be working at cross-purposes. Both Karanja and Onwonga blame the revolution of the 1960s, which promoted high external inputs, agrochemicals and high-yielding seed varieties for the sharp decline in food production.

When the World Bank and International Monetary Fund’s Structural Adjustment Programmes of the 1980s onwards came into place, the dons say, farmers who were used to subsidised inputs found themselves unable to cope.

The fact that the cycle of new fertilisers, new pesticides and new seeds has to be repeated yearly makes reliance on synthetic inputs not only costly for the average farmer, but locks out subsistence farmers.

But even for farmers who can afford artificial fertilisers, their use comes at great cost to soil health, which Karanja says, can be mitigated by employing integrated soil fertility management (ISFM) systems in which inorganic and organic systems are used concurrently.

Karanja believes that total reliance on organic inputs is impractical for Kenya’s main staple, maize, which is grown on large swathes of land.

At the same time, both scientists see organic farming as the best option for horticultural farmers, not just because they are grown on smaller plots, but they also fetch a premium on the export market.

The PS and the scientists underline the need for increasing crop production. But their approaches are different.

The scientists say Kenyan farmers use 10kg of fertiliser per acre currently. Kariuki says the national target is to raise artificial fertiliser use to 31kg per hectare by 2015, if the country is to increase production and ensure food security and income at the farm level.

However, the scientists argue that chemicals will leach into the soil, further poisoning it and reducing production. Instead, they propose that crop residues be left on the farm, by those without livestock. “You incorporate them in the (ecological) system. If you have livestock, then you feed the livestock,” Karanja says, adding, the manure from the animals is then used to regenerate the soil.

This calls for training, she says. For, while there are technologies for proper management of manure, there is a need to train farmers since poor management of farmyard manure renders it useless for nourishing the soil and increasing crop yield.

What is needed is to work with the 47 counties on ways of harvesting the vast quantities of biodegradable waste from urban markets and households.

“Why are our soils getting poorer and poorer Onwonga poses? “We harvest, we sell, and we are not returning anything to the soil” — a phenomenon Karanja calls nutrient mining. “We want a system where these materials can be returned to the farm,” he says.

Karanja challenges the counties: “They should come up with innovations of harvesting the nutrients in the urban areas,” which could also help in reducing youth unemployment. The youth, she adds, can be taught how to make proper compost, bag it and sell it. They should also be trained on how to use these products,” she adds.

According to Onwonga, fertiliser subsidies may not be the long-term solution to increasing crop or food production because inorganic fertilisers do not add organic matter to the soil.

He feels that with careful use of organic resources, they can achieve the dual function of adding nutrients and organic matter to the soil, with subsequent improvement of soil health and quality.