Precision Agriculture, also known as ‘Site Specific Crop Management’, or ‘Satellite
Farming’, is the scientific approach to what has previously been based on experience
and art, to improve the yields of a specific crop on a specific piece of land.
Every farmer has to ask him or herself-
“Why should I settle for producing 3 tons per hectare, when with the aid of science,
I can be producing 5 tons per hectare or more?”
Statistics to highlight the need for a scientific / High Tech approach make it very
The average yields of Maize (the world’s most produced staple):
(courtesy of UN FAO)
Africa < 2 tons / hectare
Zambia 1, 68 tons / hectare
South Africa 4, 2 tons / hectare
Europe 9 tons / hectare
USA 10 tons / hectare
World record (USA) 25 tons / hectare
Worst (Botswana) 0,214 tons / hectare
The better access there is to technology, the better the yields.
HTAD Zambia has made it it’s mission to change that.
Summary of factors that Precision Agriculture takes into account:
The whole area is divided into a grid and, depending on the topography, the grid
spacing is determined, average 100 metres spacing, or hectare by hectare. Soils samples
are taken at each intersection, usually correlated with precision GPS coordinates.
The samples are laboratory tested and the data loaded into software.
The weather patterns and associated rainfall, which has a direct impact on the crop
performance, are determined. By now there is a highly specialized field of study
that deals with Agro-Meteorology. Long and short term forecasts determine the planting
times and choice of cultivar. Yield monitoring Instantaneous yield monitors are currently
available from several manufacturers for all recent models of harvesters. They provide
a crop yield by time or distance (e.g. every second or every few metres). They also
track other data such as distance and mass per load, number of loads and fields.
Topography and boundaries Using high precision DGPS, a very accurate topographic map
can be made of any field. This is useful when interpreting yield maps and weed maps
as well as planning for grassed waterways and field divisions. Field boundaries,
roads, yards, tree stands and wetlands can all be accurately mapped to aid in farm
planning. Salinity mapping GPS can be coupled to a salinity meter sled which is towed
behind an ATV (or pickup) across fields affected by salinity. Salinity mapping is
valuable in interpreting yield maps and weed maps as well as tracking the change
in salinity over time. (The negative side effect of some fertilizers is an accumulation
of “salts”.) Guidance systems Several implement and tractor manufacturers are currently
producing guidance systems using high precision DGPS that can accurately position
a moving vehicle within a few centimetres. These guidance systems are replacing conventional
equipment markers for spraying or seeding. Continual Crop Monitoring By making use
of vehicle mounted sensors, satellite imaging, and Drones, data such as Infra-Red
photography to study heat patterns and associated leaf moisture content, and crop
growth rate, is gathered. Yield mapping GPS receivers coupled with yield monitors provide
spatial coordinates for the yield monitor data. This can be made into yield maps
of each field. Variable rate fertilizer Variable rate controllers are available for
granular, liquid and gaseous fertilizer materials. Variable rates can either be manually
controlled by the driver or automatically controlled by an on board computer with
an electronic prescription map. - Over fertilizing wastes money and under fertilizing
reduces yield. Weed mapping A farmer can map weeds while combining, seeding, spraying
or field scouting by using a keypad or buttons hooked up to a GPS receiver and data
logger. These occurrences can then be mapped out on a computer and compared to yield
maps, fertilizer maps and spray maps. Variable spraying By knowing weed locations
from weed mapping spot control can be implemented. Controllers are available to electronically
turn nozzles on and off, and alter the amount (and blend) of herbicide applied. Irrigation
and Fertigation Normally the rainfall has a major influence on the yield of any crop.
Carefully calculated irrigation will give plants their optimum amount of water at
the correct growth stage, to ensure best possible yield. When using certain types
of irrigation methods, any needed fertilizers and pesticides can be added to the
water to further enhance growth speed and yields. Cultivar Selection Modern seed producers
have over time developed different cultivars of a certain crop to improve disease
resistance, adapt to soil conditions, tolerate lack of water, and shorten growth
cycles. (Do not automatically assume GM). These advances in crop science have made
huge differences in production capacities. There are big databases and crop specialists,
who when provided with the data from the other spheres of expertise, can assist with
the selection of the best possible cultivar for a specific area. Records and analyses There
is sophisticated computer software available which now correlates this information
and produces graphics to represent various results. These results are then analysed
to provide historical and then predicted patterns. The yield data from the harvesters
is also added. Then costings such as fertilizer, herbi- and pesticides, fuel, maintenance
etc. are factored in to give you a good picture of what has been achieved, at what
cost and hence profits. The statistics are important as over a few seasons, a pattern
will evolve which will show the effectiveness of measures taken and further recommendations
of future activities. When this data is effectively applied, the nett profitability
of the operation is accurately determined. There are even cases of the software making
recommendations (and automatic implementation), of not planting certain parts of
the field, as they would detract from the profitability, for various reasons, and
then prompt remedial action for the following season.
What does all this mean?
For this purpose we have to ignore manual, usually subsistence farming practises,
which while, due to the large number of practitioners, make an impact on the overall
tonnage produced, the scales of economy don’t apply.
With the advent of mechanised farming the production capacities started to increase,
but so did the input costs, making the whole process more complicated.
A commercial farmer plies his trade to earn a living. I.e. make money. Therefore,
besides for producing as much as possible and being as efficient as possible, the
aim is to show a profit. The operation has to be run as a business, taking fixed
and variable expenses all into account. The aspect where agriculture is quite a unique
business is the Scale of Economy, or Economy of Scale. This formula dictates the
minimum size of operation, to be a viable business.
A very simple analogy would be the following:
If you can make a net profit of 100 ZMK, per hectare, and need to generate 1000 ZMK
to survive, you will need a minimum of 10 hectares to achieve that. To improve on
that situation, you either have to get more land, or improve on the 100 ZMK profit.
Reality is far more complex, but the principles remain the same.
A logical deduction would be to work at BPP (Best Possible Practise). Summary
From the above figures we can see the scale of economy, or economy of scale, demonstrate
itself. The larger the operation the more money is to be made. That is the logical
conclusion. Many of the successful farmers around the world are buying out the less
prosperous neighbours to expand their operations.
The next thing that can be deduced is that the tonnage produced per hectare makes
a vital difference. To produce double the tonnage does not automatically double the
input costs. The only significant cost addition is the expense of irrigation, which
now provides the means to 5 fold or more the production while only increasing the
input costs by 25%. Yes, while it is logical to deduce that more plants will consume
more nutrients, therefore there will be the added expense of more fertilizer, it
is not necessarily so.
Low-Till or No- Till, in conjunction with crop rotation technology has actually proven
that, while in seasons to come the tonnage will increase, the actual fertilizer consumption
will decrease, due to the natural soil conditions returning, and the harvesting waste
turning into fertilizer for seasons to come. For every soil condition and locality
there will come a point here the best balance has been achieved to produce at maximum
If we assume mechanized farming, the cost of machinery is high, and the associated
operating costs as well. There are modern methods, (also practised by the world record
tonnage producer), which reduce the input costs drastically. It was deemed as normal
for tractors and implements to pass over a particular field, up to 7 times in a growing
season. The revised methods cut that to 3 times, now that is a 50%+ saving, with
immediate effect, with improved results.