Small scale farmers and researchers from the University of Zambia are implementing a project to reduce the amount of fertilizer needed to grow crops – using what they call “fertilizer trees.” From Lusaka, Voice of America English to Africa reporter Sanday Chongo Kabange tells us the growing price of organic fertilizer has sparked a new innovation for Zambia’s small scale farmers who have little money.
Fertilizer trees are varieties of shrubs that capture nitrogen from the air and transfer it to the soil, a process known as nitrogen-fixing. This restores nutrients and increases crop productivity, with the potential to double or triple harvests.
The trees are already common in Zambia and are said to be affordable to small scale farmers. They can be planted among crops for up to three years before being cut and left to decompose, providing fuel and more fertilizer.
Dr. Olusegun Yerokun is a soil scientist and senior lecturer at the University Of Zambia School Of Agriculture Sciences. He says, “The concept of fertilizer trees is having trees which are able to accumulate nutrients whether from the soil or the air, and these nutrients are then recycled into soil for food crops to make use of. Where crops don’t have roots that are deep enough to access some of the nutrients these trees can go deeper, mine the soil and then food crops can use the nutrients (brought up to) the surface (by the tree roots).”
Policymakers and agricultural scientists drew up plans for implementing the program at a conference in Malawi last February. The project is targeting 200, 000 farmers -- about 10 per cent of the agricultural sector.
Yerokun says two centers in Zambia are already implementing the project at Chalimbana farming bloc and Musekera Research Center in Eastern Zambia, about 300 kilometers from the Lusaka city center. Both Chalimbana farming bloc and Musekera Research Center are run by the Zambian government and are supported by the International Center for Research in Agro-forestry based in the United Kingdom.
Yerokun says farmers receive free tree seedlings, an information kit and training on the system as well as associated crop husbandry.
The fertilizer trees begin to improve the soil as they decompose – a process that takes about three weeks. The trees are replanted every 3 years alongside food crops.
The soil scientist says, “People like ICRAF and even the government of the republic of Zambia -- through the Ministry of Agriculture -- have done quite a lot to produce seeds or seedlings which are distributed to farmers, and so they are able to access seeds from those who produce them and distribute seedlings amongst the farmers.”
According to Jeffrey Sachs, director of the United Nations Millennium Project, fertilizer trees are among the most promising means for achieving the Millennium Development Goal set up by the United Nations of halving global hunger by 2015.
There are four fertilizer tree systems all of which are based on the idea of improving soil by recovering lost nutrients.
The first system is sequential planting of nitrogen-fixing trees such as Sesbania, sesban and Tephrosia vogelli with maize, shortening the amount of time land needs to lie fallow.
In the second, Gliricidia sepium is planted among the rows of maize but heavily pruned so it does not overtake the food crop. The trees are grown between the plants.
The third involves planting nitrogen-fixing trees a few weeks after maize is harvested. This takes approximately six months before new maize is planted to reduce competition between the plants. After six months, the trees are pruned and left to decompose and the new maize is then planted.
In the fourth, tree leaves are used to fertilize vegetable crops in the wetlands or swamps as well as maize produced in the uplands or hilly areas.
More than 300,000 farmers are currently using fertilizer trees in five SADC countries -- Malawi, Mozambique, Tanzania, Zambia, and Zimbabwe.
Yerokun says the fertilizer tree initiative is nearly doubling annual maize yields in Zambia, the first country in the drought hit region to start implementing the initiative.