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

Practical Steps in Conservation Agriculture
section THREE
3.4 Mulching and stover management
We have seen in Section 1 that mulching is a key
component of conservation agriculture. Crop residues
should be left on the field after harvesting if at all possible.
Stalks should be knocked down flat and spread out as
evenly as possible. Livestock may be allowed to graze but
grazing should be controlled so that at least 30% of surface
cover remains. Additional dry organic material such as
leaves can be used to supplement or substitute for stover
if necessary, and should also be placed on the field as
early as possible in the season to buffer the soil against
extreme temperatures, suppress weeds and improve soil
fertility.
3.5 Weeding and thinning
Weeding should be done before, during and after the
season for maximum control. In this way you can prevent
weeds from growing big, flowering and setting seeds. In
successive years of implementing conservation agriculture
the weed populations of the plots should reduce.
• Winter weeding should be done after harvesting
between May and July. Winter weeding is done before
basin preparation to ensure the field is free of weeds
and to prevent dispersal of weed seeds.
• It may also be necessary to do pre-planting weeding
immediately before planting.
• Post-plant or first weeding should be done about two
weeks after planting. Weeding of the plot should be
completed in one or two days. Weed before flowering!
• Thin 2-3 weeks after germination by removing the
weakest seedling, leaving an average of two seedlings
per basin. In the event of a good germination, resist
the temptation to leave three seedlings per basin, as
this will result in a lower yield.
3 keys to good weed control
Use crop residues or mulch around the basins to protect the soil and
suppress weeds.
1 Hoe weeds when they are still very small - it’s
easier than removing bigger weeds and it reduces
crop loss.
2 Take care when planting your seeds to be precise
- this will ensure a good early crop canopy to shade
out the weeds.
3 Weed again at the end of the growing phase.
TIP: Finding mulch can be a real challenge, especially in drier areas. All participants should be
encouraged to designate a small area (such as 10m x 10m), near their homestead or access roads,
and mulch that area heavily and neatly. They should defend this area from livestock as much as
possible. This willprovide a demonstration that will convince the community of the benefits of mulch!
Farming for the Future
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