permaculture

["Lawrence F. London, Jr." <venaurafarm@bellsouth.net>]

Soil fertility and climate change: An issue pack / Radio Scripts / Farm 
Radio International
http://www.farmradio.org/english/radio-scripts/89-2script_en.asp

Two more success stories

The Gacheru Self-Help Group, a farmers’ group in central Kenya, has 
benefited by using a fertilizer made from local weeds. According to the 
farmers, the organic fertilizer solution works well and is far cheaper 
than inorganic fertilizers. The process for making the solution was 
developed by the Kenya Agricultural Research Institute and involves 
extracting juice from two local weeds, Desmodium and Tithonia. These 
weeds are high in nitrogen, which boosts crop yields, says farm manager 
Samuel Mugo. "They fight all manner of destructive weeds and give us 
high yields from our farms." The process is simple. The farmers thresh 
the weeds, then mix them with water in a drum. The solution is then 
ready to use.

Zambian farmers use termite soil to improve soil fertility: Zambian 
farmers traditionally used soil from termite mounds as a fertilizer. But 
when inorganic fertilizers became available at subsidized prices, this 
practice declined in popularity. When the subsidies were removed, many 
farmers resumed the practice.

A suitable termite mound is chosen and cleared of vegetation. Soil from 
the top of the mound is removed, but the base is left intact so that the 
colony is not destroyed. The soil is transported to the field and, 
before the rains begin, farmers work it into the topsoil with ploughs, 
hoes or shovels. Where farmers practice conservation farming, the soil 
is placed in planting pits.

The termite soil is applied once every three years. Maize harvests were 
33 percent higher in fields with termite soil than in fields where 
inorganic fertilizers were used. Termite mound soils have lots of clay, 
which improves water storage. In southern Zambia, soils are normally 
poor at holding water, so using termite soil helps hold more water and 
improve crop yields. Termite soils also have high levels of calcium, 
phosphorus and organic matter, which all contribute to better crop 
yields and health.

Other useful practices for improving soil fertility include:

    * Composting: Making compost involves combining fresh “green” plant 
materials which contain lots of nitrogen (for example, fresh leaves and 
kitchen food waste) with older “brown” materials such as crop residues 
which are high in carbon. These materials are mixed and then broken down 
– normally in a compost pit or compost pile – through aerobic 
decomposition (decomposition in the presence of oxygen) into a rich 
black soil. The decomposition is performed by micro-organisms, mostly 
bacteria, but also yeasts and fungi. The process of composting is simple 
and can be practiced by individuals in their homes, farmers on their 
land, and by people living in cities. There are many ways to create and 
use compost. To learn about various methods, see Farm Radio 
International scripts on compost at 
http://www.farmradio.org/english/radio-scripts/fertilization.asp.
    * Animal manure: Animal dung contributes to soil fertility by 
adding organic matter and nutrients, especially nitrogen. Livestock 
manure often includes plant materials such as the straw used for animal 
bedding. Livestock bedding is also useful because it has often absorbed 
animal dung and urine.
    * Using rock phosphates: These are mined rocks which contain 
phosphate, and which are used to provide the mineral phosphorus, the P 
in N-P-K. Natural deposits of rock phosphates are found in Senegal, 
South Africa, Mali, Tanzania, Nigeria, Niger, and some other African 
countries. See further resources at 
http://farmradio.org/english/radio-scripts/74-8script_en.asp and 
http://www.uoguelph.ca/~geology/rocks_for_crops/
    * Agroforestry: Growing trees and shrubs together with crops 
reduces the loss of soil nutrients.  Because trees and bushes usually 
have highly developed root systems, they can absorb and store many 
nutrients which are unavailable to crops with shallow root systems. In 
this way, trees and shrubs keep nutrients from being leached during 
periods when no other crops are being cultivated. After the leaves or 
cuttings fall to the ground, the nutrients once again become available 
to the crops as the leaves and cuttings decompose. Trees and shrubs can 
also form hedges that protect crops and soil from wind and from heavy 
rains which runoff over the surface of the soil. For example, in West 
Africa, Acacia species increase soil fertility by providing organic 
matter in its leaves, fixing nitrogen in the soil, capturing nutrients 
with its extensive root system, and shading cattle in the dry season 
(the cow dung enhances soil fertility).