Food for All - Agri-culture: Reconnecting People, Land and Nature - page 88

controls are enhanced with surface mulch and crop rotations, it has also
become possible to reduce the amount of pesticides used, with some
success in herbicide-free management. Other benefits of zero-tillage
include reduced siltation of reservoirs, less flooding, higher aquifer
recharge, lowered costs of water treatment, cleaner rivers, and more winter
feed for wild biodiversity. 16 A large public good is also being created when
soil health is improved with increased organic matter. Organic matter
contains carbon, and it is now recognized that soils can act as sites for
carbon sequestration. Not only are these sustainable agriculture farmers
creating a soil of good health, they are providing a benefit to us all by
sequestering large amounts of carbon from the atmosphere, in this way
mitigating the effects of climate change. However, there is still controversy
over zero-tillage. Some feel that the use of herbicides to control weeds,
or the use of genetically modified crops, means that we cannot call these
systems sustainable. However, the environmental benefits are substantial,
and new research is already showing that farmers have effective agro-
ecological alternatives, particularly if they use cover crops for green
manures in order to raise organic matter levels. 17
In the Sahelian countries of Africa, the major constraints to food
production are also related to soils, most of which are sandy and low in
organic matter. In Senegal, soil erosion and degradation threaten large
areas of agricultural land; and since the late 1980s, the Rodale Institute
Regenerative Agriculture Resource Centre has worked closely with
farmers' associations and government researchers to improve the quality
of soils. The primary cropping system of the region is a millet-groundnut
rotation. Fields are cleared by burning, and then cultivated with shallow
tillage using animals. But fallow periods have decreased dramatically, and
inorganic fertilizers do not return high yields unless there are concurrent
improvements in organic matter. Soils low in organic matter also do not
retain moisture well.
The Rodale Centre now works with about 2000 farmers who are
organized into 59 groups on improving soil quality by integrating stall-
fed livestock into crop systems, by adding legumes and green manures,
by increasing the use of manures, composts and rock phosphate, and by
developing water-harvesting systems. The result has been a 75 to 190 per
cent improvement in millet and groundnut yields - from about 300 to
about 600-900 kilogrammes per hectare. Yields are also less variable year
on year, with consequent improvements in household food security.
Amadou Diop summarizes an important lesson for us all: 'Crop yields are
ultimately uncoupled from annual rainfall amounts. Droughts, while having a negative
effect on yields, now do not result in total crop failure.' 18