See pictures at the bottom
Introduction
Towards the end of the January 2015, the veggie tunnel project in
Walvis Bay received a sponsorship from the Manica Group for the amount of
N$24 000.00 to implement an irrigation system. This project was carried
out by Francois van Niekerk.
The irrigation system is an ‘EZ-FLOW better science’ model and uses a
Hunter Pro 17A controller, which gives you 10L of water per minute, based on
municipal pressure.
Challenges
Over watering
The system provided more water than it is required, even in weather
where it does not allow for watering. This was confirmed by the access amounts
of algae in the tunnels. The plant’ growth was seriously hampered by this
over-watering.
As a result, Emmanuel suggested to the Centre, to stop watering for 2
to 3 days, until the moist has settled down and the algae disappeared. They
should go back to the manual watering, after that.
The measured amount of water that went into each tunnel was 460L per 7
minute, which is way above the recommended need per tunnel.
Fertilizer
The hydroponic fertilizer is mixed in a small tank. The challenge is
that we cannot tell which tunnel is getting what amount of water and
fertilizer. Hydroponic fertilizer is usually pre-mixed in a tank, after which
the water was pumped to the plants in a controlled way. In this case the water
was flowing through the mixing tank with no way to tell how much fertilizer is
applied
Due to this inconsistency and over-watering, some of the plants became
yellow and other light green.
Sprayer used
The sprayers that were used gives 10L of water per minute and have a
radius of 5.5m, while the tunnel is 3.8m by 12m. These sprayers overs-prayed
the tunnels.
Recommendations
Irrigation
After some tests by Emmanuel Muyumba and Francois, it was discovered
that the irrigation system provided more water than was required. This led to
some calculations for the better use of the system. They decided that the
automatic irrigation system should run for 3 minutes only, to give the right
amount of water needed for the tunnels.
This will be done on an evaluation basis, to see how the vegetables
perform. The ratio for fertilizer application will also be changed. The centre
will keep a record of how much fertilizer is being used and for how long is the
system running. This will lead to an efficient way of using the irrigation
system.
Planting
Emmanuel addressed the challenge of delays in harvesting and proper
planting practise. The lettuce was supposed to be harvested weeks ago, but has
still not matured due to incorrect hydroponic mixing. The gardeners were also advised
to mix the fertiliser regularly. Some of the planting bags were planted too densely, which led to the slow
growth of spinach. Then there was a low planting density in the bags for carrots.
Results achieved from the first planting:
-
The harvest of Spinach was done weekly
-
Onions were harvested small, as baby onions for
the kitchen
-
The Beetroots did not come out so good, due to
insufficient fertiliser
-
Beans had a total harvest of 41 Kg and was sold
or used for consumption
-
Peas had a harvest of 17Kg
-
Cauliflower did not perform well due to disease
and pest
-
The Broccoli did not perform well due to disease
and pest
With all the challenges that the centre has experienced, they were
still able to bring in a considerable income for the Centre.
Conclusions
After all the tests were done on the new irrigation system for the
veggie tunnels, the team came to the conclusion to ‘reduce the amount of water
used for irrigating’. They also had discussions with the engineer who installed
the irrigation system, to make the necessary changes to compensate for the
problems found. The system will work with these changes for a trial period of 1
month, after which it will be re-evaluated for the use in veggie tunnel
production.
As part of his program Emmanuel gave training on:
-
Planting
-
Harvesting
-
Crop Rotation
The students also received a training manual which they could refer to,
during their challenges. This training manual was compiled by Emmanuel and used
during training in veggie tunnel production.
They also received a moist meter to help solve the overwatering issues.
Emmanuel Muyumba
Trainer of Trainers in Organic Horticulture
DiHokoHoko - Divundu
+264813899866
PO Box 4774
Windhoek
Namibia
