A Guide to Conservation Agriculture in Zimbabwe - Canadian ...

section ONE
Promoting Conservation Agriculture Among Farmers
conservation agriculture techniques, so too will the amount
of crop residues. Crop residues are not the only mulch
available: farmers can harvest grass, leaves and kitchen
compost to place on the soil as a blanket. Some other ideas
for tackling these challenges are presented in Section 3.
Mixing and rotating crops
Intercropping and crop rotation has been promoted in
Zimbabwe since the early 1970s and it is not a new concept
to farmers! Mixing different crops in one field echoes
processes found in nature and can maximize plant nutrient
use by synergy between different crops. Conservation
agriculture encourages profitable and agronomically
efficient rotations: usually cereal and legumes or cash crops.
Taken together, these practices have the following
advantages:
• replenishing soil fertility: intercropping with nitrogenfixing
legumes adds ‘top-dressing fertilizer’ to the soil;
• enabling crops to use the nutrients in the soil more
effectively: intercropping different crops with different
feeding zones which do not compete for nutrients
may help prevent a hard pan forming;
• helping to control weeds, diseases and pests by
breaking their life cycles through the introduction of
a new crop;
• reducing the risk of total crop failure in cases of drought
and disease outbreaks.
However farmers in Zimbabwe rarely practice rotation for
a number of reasons. Shortages of legume seed restrict
planting. Legumes are normally grown for local
consumption only, so if production is increased then
additional output markets will be needed in which to sell
the surplus. Farmers often give priority to growing cereal
crops because cover crops compete for moisture. This last
reason is a problem that conservation agriculture helps to
overcome and thus helps intercropping to become a viable
Intercropping in Matobo District of Matabeleland South: Intercropping
maize with cowpeas provides cover, reducing soil erosion and ensuring
a better nutrient balance through nitrogen-fixing.
Timely implementation
A key principle of conservation agriculture is the need for
timely implementation.
This means:
• preparing the land in good time before the rains start;
• planting soon after an effective rainfall event;
• weeding at appropriate times and intervals, during
the winter usually two to three weeks after emergence,
then at six weeks, and finally at the end of the rains;
• doing effective pest and disease control before either
spread too widely.
Where conservation agriculture has not produced the
expected results, it is often due to a lack of timeliness of
operations. Practitioners of conservation agriculture have
learned not to cut corners in the early part of the season as
this will cause more work and lower yields later on. Table 1.1
below is a guide to when operations should be carried out.
A detailed calendar of activities is provided in Section 4.
5 Farming for the Future