Transcript Dia 1 - Spate Irrigation

5.3
SORGHUM
SORGHUM: THE HARDY PLANT SOME FACTS
Sorghum is grown in warm or hot regions that have summer rain-fall, even if rainfall is
as low as 400-600 mm.
The most favorable mean temperature is about 37oC. The minimum temperature for
growth is 15oC. The sorghum plants seems to withstand extreme heat better than
other crops.
Sorghum is practically dormant during periods of drought but resume growth as soon as
there is sufficient water to wet the soil . This characteristic accounts in large part for
the success of sorghum in a dry season
As compared with corn of similar seasonal requirements , sorghum has more roots and a
smaller leaf area per plant . A waxy cuticle retards drying.
Sorghum is grown successful on all types of soil.
Botanical description
Sorghum belongs to the family
Graminea. Sorghum is a coarse grass
with grows 0.5 to 5.0 meters in
height. A leaf arises at each node.
Crown buds give rise to tillers
The total number of leaves on the main
stalks , including those formed during
the seedling stages , averaged 16 to
27 per stalk . Early maturing varieties
have few leaves and consequently are
limited in plant yield .
The sorghum inflorescence is a loose to
dense panicle having many primary
branches borne on a hairy axis
Central Issue:
Sorghum
yields in
Pakistan
are very
low – 0.20.6 ton/ ha
compared
to other
countries
but esp
compared
to Eritrea
where they
reach
>2ton/ha
Cultivation
•
•
•
•
•
•
Seedbed preparation
Irrigation
Hydrocyanic poisoning
Planting density
Weed control
Use of fertilizers
• Harvesting
• Ratooning
• Rotations‫ا‬
Seedbed cultivation
Moldboard plowing is common practice for seedbed
preparation in humid and irrigated areas.
The yields may be increased from 25 to 30 % by
thorough tillage of medium –heavy soils.
Weed control before planting is desirable.
Most of the fields in the semiarid region are tilled by
stubble –mulch.
Irrigation
From 50 to 60 cm of water consisting of stored soil moisture,
rainfall and irrigation is required for a maximum yield of
sorghum . Of this amount ,some 20 to 50 cm of water
must be supplied by irrigation in the sub humid , semiarid
and arid regions .Preplanting irrigation wets the soil to its
field-carrying capacity to a depth of 180 to 200 cm will
reduce the number of summer irrigations . The maximum
water usage is during the boot stage of plant growth when
2.5 cm of water is consumed during 3 or 4 days. Yield may
more than double on providing additional spate irrigation
turns – as the plant is no longer stressed.
Hydrocyanic Acid Poisoning
Young plants including the roots and especially the leaves of
sorghum contain a glucoside, which upon breaking down releases
the poisonous hydrocyanic acid (HCN).
Losses of cattle, sheep and goats occur each year from sorghum
poisoning when they graze upon the green plants. Small plants,
and young branches and tillers are high in hydrocyanic acid.
Planting density
Sorghum for grain, fodder or silage is usually planted in
rows 0.5 to 1.0 meters apart. A sorghum planter or
other types of row planters with special sorghum
seed plates can work satisfactory.
The amount of seed to plant per hectare depends upon
the condition of the seed size and weather conditions
at seeding time.
Weed control
From two to four cultivations are required to control
the weeds in sorghum that is planted in rows.
Fewer cultivations are required when the sorghum is
planted in furrows.
Weed control with herbicides is less satisfactory in
sorghum than in maize for instance, because the
sorghum plants are more sensitive to the
chemicals.
Use of fertilizers
In semi-arid areas sorghum responds strongly to
applications of farm yard manure or nitrogen.
This is an argument to intercrop sorgum
with guar
Harvesting
Cut the plants at ground level and laid them on the ground between
the rows. Leave the cut plants for 4-5 days to dry up. This
conserves soil moisture to be used use by the ratooned crop.
If the plants are left on the ground for longer period, the grains will
start to change color and develop an unpleasant smell.
Cut off the ear heads and transport to the threshing ground. Leave
there there for 1-2 weeks, until the plant is dry enough to be
threshed easily.
Sorghum is harvested when the crop is matured ,
but not when it is fully dry . This is done to allow
enough time for the ratoon crop develop . So some
farmers harvest the main crop 10- 15 days ahead
of the normal harvesting time .
.
The process of harvesting is :
cut the plants at ground level and laid them on the ground between the rows
left the laid plants for 4-5 days to dry up . This conserves soil moisture to use by
crop ratoon . If the plants are left on the ground for longer period , the grains
started to change color and develop an unpleasant smell .
cut off the ear heads and transport to threshing ground , and leave there for 12 weeks until they are dry enough to be threshed easily .
‫ا‬RATOONING
Crop ratooning is highly practiced in the spate
irrigation in many areas. It has short growing
period requirement ( 20 -30 days).
Ratoon yields are lower than the first yield
(30%). Sometimes a second ratoon is also
harvested – often for fodder only. Varieties are
selected on their capacity to ratoon.
Rotations
Sorghum follows other crops readily, but care should be exercised in the
choice of the crop to follow sorghum .
: ‫الدوره الزراعيه‬
‫ لكن زراعة أي محصول بعد الذره‬, ‫يمكن زراعة الذره الرفيعه بعد أي محصول‬
.‫الرفيعه مسأله يجب النظر فيها‬
Livestock
•
Close link with livestock:
– Fodder
– Tilling land
– Construction and maintenance of structures and field
bunds
– Transport
– “Money deposit” (buy in good year, sell in bad year)