Agriculture Reference
In-Depth Information
Some on-farm systems are linked on a network basis (e.g., PLANT-Plus, Raatjes
et al
., 2004), supplementing the regional weather forecasts. It is the scale of the
network required that is worthy of investigation, particularly in areas like the UK
with its varied topography and weather systems when compared with countries like
the Netherlands, with a more uniform weather system. Bourke (1953) was sceptical
and commented “However, it is unfortunately true that even an expensive network
of special weather observations from every potato field in the country would not
fully cover the local variations in susceptibility to blight”. It should, nevertheless,
not prevent us from trying.
Whether an individual station or a network is appropriate will largely depend
upon the pathogen. Forecasts of pathogens that build up rapidly and spread long
distances, such as potato blight, may respond better to a network of stations while
splash-borne pathogens, such as
Septoria
, can be covered from a single station
within the field.
9.9.3 User
The second and potentially major constraint is the farmer. Will he use a forecasting
system? Farmers are keen to produce their crops as economically as possible and
any system that will enable them to save money will be favourably received. Also,
farmers are coming under increasing pressure from their customers, particularly
the large supermarket chains, to justify pesticide use. Forecasts provide this
justification.
There are various degrees of providing the farmer with the necessary information
on the actions that should be taken. Some systems are passive, in that data are
obtained from a synoptic meteorological station, interrogated by the meteorological
service for the appropriate criteria and the information fed to an extension service
for interpretation and dissemination. Other systems may require farmer input,
weather recording, monitoring crops for the presence of disease and identifying a
threshold. The farmer may be prepared to do this himself or contract it out to a
specialist consultant. Where computer-based systems are used, the latter is the most
likely scenario. Where computer-based systems are required, it is obviously
necessary not only to possess the hardware but to commit the time and effort to run
the models.
A further constraint are farmers' concerns about the reliability of forecasting
systems. Generally, a farmer's measurement of the success of advice is the
appearance of his crop and whether the yield expectation is realised. For a
commercial consultant, where repeat business is essential, it is likely that crop
appearance is all important. This pushes consultants towards insurance and
scheduled spraying rather than timely forecasts. There are also practical difficulties
to overcome, scheduling being one, particularly when repeat spraying is required, as
with potato blight. The ability to get round all fields at risk is a major logistical
constraint and it is often easier, once started, to maintain a 7- or 10-day schedule
rather than one varied according to risk. The increasing use of contractors for spray
operation also means that they have to be reserved in advance and this imposes
