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Issue 28: November-December 2003

New product could help ease
Zambia's agricultural shortfall

A Zambian woman prepares seed for planting. PAPR could boost the country's flagging agricultural production.

The Mineral Resources Unit of UNU Institute for Natural Resources in Africa has begun a project to improve soil fertility in Zambia by turning phosphate-rich rock into fertilizer.

Zambia's food production over the last three decades has declined to the point where a country that once was able to feed its people now depends on food imports and foreign food handouts to avoid widespread starvation. 

The main reasons for the drop in production are frequent drought and degraded lands that were not particularly fertile to begin with, lacing essential nutrients such as phosphorous.

For farmers struggling to survive, an alternative to  expensive imported phosphorous fertilizers could be locally available phosphate rocks. However, these are only slightly soluble and cannot supply enough plant-available phosphorous for crop growth within the short growing season. 

It is against this background that the Mineral Resources Unit (MRU) of UNU-INRA initiated a project to make the phosphate rocks more soluble by applying small quantities of mineral acids, resulting in a product called partially acidulated phosphate rock (PAPR) .

In collaboration with scientists in the School of Agricultural Sciences of the University of Zambia, PAPR produced by MRU from Chilembwe phosphate rock has been field tested on different crops in Zambia's various agricultural zones. Results show that when applied to maize (Zambia’s staple crop), sunflower, soya beans and groundnuts, PAPR was as effective as imported mono-ammonium phosphate (MAP). 

The results also show that PAPR is more suitable than MAP for long-term improvement of the phosphorus content of the soils because it acts as a slow release fertilizer with longer-lasting residual effects on succeeding crops, while the application of MAP at high rates resulted in zinc deficiencies which depressed maize yields.

In combination with low-cost locally produced agricultural lime, PAPR was found to be very effective on the highly acidic soils of north-western Zambia. The product has been demonstrated to more than 4,000 farmers during a series of field days and the the response has been outstanding.

At one of the Field Days, which attracted a broad spectrum of small, medium and large scale commercial farmers, Zambia's President Levy Mwanawasa said that PAPR has the potential to transform Zambian agriculture. Thousands of farmers, both small-scale and commercial, have asked the government to make PAPR available.

MRU has received a request from one of Zambia’s large commercial farms to produce 30 metric tonnes of PAPR for the next cropping season while a group of export-oriented farmers want 35 metric tonnes of ground Chilembwe phosphate rock for the production of “organic” crops. 

PAPR produced from the small MRU pilot plant has been supplied to the Riverside Farming Institute near Lusaka where small-scale farmers are learning various techniques to improve income generation and food security. In another development, ZAMPHOS, an indigenous mining company with exclusive rights to mine the Chilembwe Phosphate rock deposits has approached the MRU to conduct a feasibility study on the viability of large-scale production of PAPR. MRU has submitted a proposal and is awaiting response from ZAMPHOS.

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