Agrinews January 2013 - Ministry of Agriculture

continued from page 15
...both social and economically.
All crops grown are suitable for fodder
but not all farmers take notice of
that. Main crops such as graminae
and leguminous family like Maize,
sorghum, millet cowpeas, groundnuts,
jugobeans, are widely grown in
country but it is common that after
grain harvest the whole Stover products
is left standing in the fields and utilized
by cattle and untimely. Farmers should
be encouraged to take an advantage
of making hay out of that to avoid
starvation during dry season and fetch
more cash.
To cut failed crops while still green and
dry them without losing green color
indicates valuable nutrition then can
be chaffed and sacked, or bailed to
feed livestock during dry seasons will
be an advantage.
Growing the recommended fodder
species is very vital for:-
• Drought resistance
• Tolerance to most soils of Botswana
Question
&
During growing seasons, and in an
event of poor crop performance and low
germination percentage, the contributing
factors are in most cases according to
traditional farmers, lack of soil moisture
content and poor quality seeds. But
the fact of the matter is that there are
many contributing factors such as Soil
compaction which farmers may not
be aware of. Agrinews reporter Joseph
Ramodisa is having a conversation
with Dr Flora Pule-Meulenberg, from
the Department of Crop Science and
Production at Botswana College of
Agriculture about soil compaction.
Q. What is Soil Compaction?
A. According to the Soil Science Society
of America (1996), soil compaction
is “the process by which soil grains
are rearranged to decrease void space
and bring them into closer contact
with one another, thereby increasing
the bulk density”.In very simple terms,
soil compaction is the destruction of
the physical characteristics of a soil or
the physical degradation of the soil.In
soil compaction, the first property of
the soil to be destroyed is its structure.
Soil structure refers to the spatial
arrangement of the soil constituents
and aggregates. Once the structure is
destroyed, the pore space deteriorates
and hence the capacity of the soil to
retain moisture as well as its ability
to circulate air becomes limited. The
type of pores that transports air and
warmth around the soil profile, (called
macropores) are the same ones that
make it possible for water infiltration, be
• Ability to spread naturally
• Vigor of growth and growth rhythm
fully expanded leaves developed
at the rate of every nine to ten days
in summer 11days in spring and 14
to 12 in autumn with senescence
highest in the summer growing
seasons and slowest (Wilson &t
Mannetje 1978)
• Suitable for hay and silage the
grass makes reasonable quality hay
when cut in the early flowering
stage, yielding up to 2500kg/ha
per cut with a protein content
of 6-10 percent of dry matter.
Old grass, after the seed has
harvested, can give low-quality
roughage for drought feeding with
supplements. This old grass will
have protein content of 4-6 percent
(Shankarnarayan 1977) while a
mature animal require 7% protein
for maintenance for survival.
The grasses are economic hence are
best forage grasses found natural in
semi-arid, subtropical and tropics
areas, and Botswana is the exemplary
grasses habitat of many species.
To make hay from the grass is convenient
and save starting from December to
March when grass nutrients is high and
when there is plenty of sunshine.
Tools required - Framing box (form)
Scythe, Rake, Wire or string.
Cut the grass in the morning with
a sharp scythe when half of it has
flowered. Make sure the grass is spread
by tuning it once using a rake and leave
it overnight for it to dry smoothly.
Start bailing the dried grass the second
day after cutting, by fill the dried grass
in box with dimensions of 90cm length,
60cm width and 60cm depth and pack
it tightly in the box by trampling on
many times then tie compacted grass
with wire or string lift the box to
release the bale if well packed is about
15kg and it estimated that 2 men can
make 60 bales day. (APRRD www.dar.
gov.bw)
Answer: SOIL COMPACTION
it from rainfall or irrigation. Therefore, a
compacted soil will likely have problems
of water erosion due to increased
surface runoff. The physical degradation
of the soil will lead to the deterioration
of some chemical properties. Because
compacted soils do not have much
air circulation, microorganisms that
are responsible for organic matter
decomposition and other important soil
processes cannot survive. This leads to
poor fertility of soils since organic matter
is an important source of nutrients such
as NPS. Another consequence of that
scenario is that only anaerobic microbes
will thrive, resulting in conditions
that promote toxically high levels of
micronutrients (iron, zinc, manganese
and copper) for plant growth. Ultimately
for arable systems, soil compaction
will lead to yield reduction through
limiting fertility including interferences
with moisture and nutrients.
Q. Where Does It Occur?
A. Soil compaction can occur in
natural ecosystems as a result of animals
trampling on wet soils, for example
at watering points, human beings
through construction (building, roads,
pavements etc). For arable agriculture,
compaction is caused by vehicles
such as tractors, cars and their use at a
particular moisture content.Ploughing
or tilling a soil continuously with a
mouldboard can lead to a compacted
layer below the tillage depth in soils
that are high in clay content. Soils
that are high in clay content and
low in organic matter compact very
easily. For arable soils, as a rule of
to be continued in the next issue
thumb, the heavier the equipment used,
the higher the level of compaction.
Q. To minimize soil compaction what
should farmers do?
A. There are several ways in which
farmers could limit soil compaction.
Tilling wet soils should be avoided
at all times. This leads to formation of
puddles (seretse!) and when they dry
they form clods (magwete!) that are
hard for seedling to break through.
Compaction has also been shown to
increase with vehicle weight. Especially
for commercial farmers, increasing tyre
size has been shown to not compensate
for increased axle load and it spreads
compaction over a greater volume
of the soil. It is a good practice not to
carry very large loads on wet soils and
to maintain proper tyre pressure. If it
is necessary to drive on wet soil, it is
better to stay on the same tracks to avoid
compacting a larger area or volume of
soil. Regarding the use of a mouldboard
plough, formation of a plough pan
(compacted layer) will lead to decreased
water percolation to the subsoil and
may be avoided by deep ripping the
soil once every four to five years.
Q. What are the potential concerns
about soil compaction?
A. In summary, the main concerns about
soil compaction include loss of moisture
holding capacity, decreased rooting
zone, loss of C, N, and P sources, changes
in soil pH, changes in soil bulk density
and increased erosion due to increased
runoff as a result of limited infiltration.
Kakamane educational tour - Serowe
Article & Photos: Felix Mothatego
Agricultural specialists, interested
parties and farmers from Serowe
village and surrounding areas
discussed modern farming technology
during educational tour at Kakamane
fields, recently.
The Department of Crop Production
organized this event which attracted
incredible people out there. We were
blown away by level of commitment
and community we found along the way.
Small scale farmers appreciated that
nowadays ploughing is mechanized,
and tractor ploughs as much as
30 times as a man with donkeys.
They also saw reality of what goes on
at sustainable small farms, and the
need to better connect as farmers.
The agricultural demonstrator,
Gaopotlake Gabalebatse said they
focused on the use and maintenance of
tractor/farming implements, seed bed
preparation, and fertilizer application.
He said farmers are not producing
enough yields because they do not
use modern technology. Some have
agricultural implements but lack
information and experience.
As such, they encouraged farmers to
exchange information and get assistance
from demonstrators.
“I think you have seen that most of them
do not know how to calibrate a planter.”
One of the farmers, Rasebolai Kgamane
said he has implements but does not
know how to use them.
He said he is happy to have got
information on plant population, use of
a planter and fertilizer application.
The host farmer, Keataretse Monamo
said she will improve her knowledge
by being present when a tractor
operator is ploughing and sowing.
She has learnt a lot about
moisture conservation, use
of fertilizer and pesticides.
She challenged fellow farmers who have
not been using modern technology to try it.
For his part, Baitirele Mothaleemang said
it is unfortunate that even government
tractors ploughing for farmers do not
come with all necessary implements.
He said as a consequence. farmers
prefer broadcasting seeds because they
want to sow before moisture evaporates.
Unlike many farmers, Mothaleemang
will be on his third year row planting
and has been happy with harvest since
he started it.
This event was undoubtedly important
because it helped small scale farmers
and general public realize there is so
much out there on how to produce
food.
January 2013 January 2013
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