Bien Donné Farm - Agri Promo

Mechanisation and Water:
An Odd Couple
Compiled by
Doug Momberg
AMG Media &
Promiotions
T
he connection between water and mechanisation
is not one that first meets the eye. However,
deeper inspection into the relationship
between the two highlights some interesting insights.
It is important to realise that agriculture is the largest
extractor of water resources, accounting for an estimated
70% of all water consumption worldwide.
A striking fact regarding water availability in the SADC
countries is that the per capita water availability, which
is already low, is expected to reduce by half by the
year 2025. This is further compounded by the realisation
that the water basins that make agriculture possible
in South Africa are all shared with our regional
neighbours. Agriculture, as by far the largest water
extractor, is therefore poised to lead the way in addressing
and determining the management and governance
of these resources, before it is done on their
behalf. Agriculture in this sense stands to gain, and
potentially loose the most, if this is not addressed.
For this to take place, a keen understanding is required
about aspects and effects of water usage
practices and the various ways that consumption
can be limited. The international trade in agricultural
commodities at the same time constitutes a trade with
water in virtual form. Below is a table that displays the
waterfootprint of a number of products, which demonstrates
the dire need to conserve water where possible,
in order to maintain the capacity to produce the
food products that society relies on.
Invasive alien vegetation that is, in other words, not
indigenous to the region, are highly detrimental to
agricultural water usage. Black Wattle, for instance,
uses 6000m3/ha/annum, while Vines, on the other
hand, utilise 4500m3/ha/annum. Furthermore, 55%
stream-flow reductions in fynbos catchments have
been reported, 23 years after planting pines. The replacement
of grasslands with pines and eucalyptus
in Mpumalanga, KwaZulu-Natal, and Northern Province,
has resulted in streams completely drying up
6-12 years after planting. Combatting this scourge
highlights the first of the relationship between wa-
BIEN DONNÉ AGRI CAPE WEEK 2012
ter and mechanisation. Eradication of invasive alien
vegetation can be approached through a number of
techniques. The most effective means is the cutting
down of the offending vegetation; a number of products
and services are available ranging from handheld
and chain saws to private contractors. Recycling
of the wood can take the form of either chipping for
mulch or firewood.
Earth moving and tillage also have implications for the
water on farms. The laws of displacement come into
effect through the moving of soil. When soil is moved
from one place to another, the water table adjusts accordingly.
This can be either to one’s detriment or manipulated
to your advantage. An understanding of the
water resources in the production area can therefore
be a major benefit.
Irrigation is probably the most obvious connection
between mechanisation and water usage. Efficient irrigation
regiments are imperative for the sustainable
preservation of water resources. Considering the agricultural
irrigation practices in regions where water is
particularly scarce, can provide insights into the possible
alternatives and improvements that can systematically
be brought about. Drip irrigation, for instance,
has proven to be highly effective in the water scarce
Middle East, with significant increases in production
yields.
The particular methods that are employed to best utilise
and preserve the water resources available are,
of course, dependent on the particular production
requirements. The need, however to consider adjustments
and adaptations to the manner in which water
is exploited is already imperative, and will only become
more necessary as time goes by.
The aforementioned is also supported with the realisation
that food and human security are both inextricably
dependent on water security.
Food Item Unit Water Footprint (l)
Apple/Pear 1kg 700
Beef 1kg 15 500
Cabbage 1kg 200
Cucumber/Pumpkin 1kg 240
Lettuce 1kg 130
Maize 1kg 900
Olive 1kg 4 400
Orange 1kg 460
Peach/Nectarine 1kg 1 200
Potato 1kg 250
Sugar 1kg 1 500
Tomato 1kg 180
Wine 125ml 120
Source: The water footprint of food, Professor
Arjen Y. Hoekstra, University of Twente Water Centre,
Netherlands.
30 www.agrimega.co.za