 |
| Women digging Modified Zai pit holes in Mivukoni, Kyuso, Kenya |
Introduction
Maize
is one of the most popular crops in agro ecological zone LM4 in Kyuso
district. Kyuso district experiences an average annual rain fall ranging
300 to 600 millimeters in two seasons per year. Due to the erratic
nature of the rains, there is a crop failure for 3 in every 5
consecutive seasons. This calls for water harvesting as an intervention
to address the moisture shortage that causes the inherent crop failure.
Modified Zai pits
Zai
pits as a water harvesting technology integrates a variety of factors
to avail moisture to the growing crop to attain physiological maturity
as follows:
• Cultivated (cropped) area: The
soil condition of the cropped area must be well prepared to reduce any
soil related limitations for optimum crop establishment and growth
• Catchment area: This
must be sufficient to generate the extra moisture required in the form
of runoff. A Catchment cropped area ratio of 3:1 has been found
appropriate.
• Catchment characteristics: As
much as possible the catchment should be modified to minimize
infiltration. This may be achieved through increasing the catchment
gradient towards the cropped area and compaction.
• Efficiency: In
order to optimize the crop yield, both the normal rains and the runoff
that collects at the cropped area must be used efficiently by the crop.
All moisture losses must be minimized. The right crop variety with
vigour must be planted early enough to gain from all the moisture
experienced at the cropped area. It is advantageous to plant with
Phosphorus containing fertilizers for early crop root establishment. Top
dressing with Nitrogen and use of farm yard manure for provision of
extra nutrients and moisture retention is necessary. Since weeds will
compete for moisture and nutrients, weed control will be of necessity.
Use of mulch will reduce evaporation losses. In addition since a health
crop will use the soil resources efficiently, it will be necessary to
protect the crop against pests and diseases.
Zai pits dimensions and lay out
For
proper crop rooting zone Zai pits for Maize must have a minimum of 30
cm depth. They may be circular with varying diameters or varying square
sizes depending on the anticipated number of plants per pit. A square
Zai pit measuring 75 x 75 x 45 (cm) is ideal for 9 maize plants in
Kyuso. They are convenient to dig and the sub soil is used to form a
soil bund 15 cm high around the catchment area, while the top soil is
returned and mixed with farm yard manure at a ratio of 4:1. Less manure
ratio could be used depending on the top soil quality, manure
availability and complementary use of artificial fertilizers.
Economics
An
acre will accommodate 1778 nine plant pits each measuring 75 x 75 x 45
(cm) with a catchment area 3 times its size or 1.7 M2 and a plant
population of 16000. At the minimum the yield from one pit will be 1.5
kg which translates to 30 bags of maize from one acre.
Conclusion
Going
by the current market prices of maize, it is profitable to invest in
water harvesting for maize production in the ASAL. During times of
relative low prices, the margins will go lower. However the intervention
will have other advantages like food security and employment creation.
The area being a livestock zone the maize Stover will be used as
livestock feed. The
intervention has a positive environmental impact in that it
effectively brings runoff under control.
Income statement for maize production through Zai pits
Yield per acre is 30 bags @ KES 2000 translating to a gross income of KES 60,000
|
Cost of 10 kg seed
|
@140
|
1,400
|
Cost of 1778 Zai pits distributed into 6 seasons
|
@30
|
8,890
|
3 x 50 kg fertilizers
|
@2500
|
7,500
|
593 debes of FYM (each debe serves 3 pits)
|
@10
|
5,930
|
8 m/days of weeding
|
@200
|
1,600
|
Insecticides
|
Assorted
|
2,000
|
8 m/days of harvesting
|
@200
|
1,600
|
2 m/days dusting and spraying
|
@200
|
400
|
30 gunny bags
|
@50
|
1,500
|
10 m/days threshing and
winnowing
|
@200
|
2,000
|
Total variable costs
|
32,820
|
-32,800
|
Gross margin
|
27,180
|
