15 March 2002

MAPPgets a thumbs up

"MAPP", the Management Advisory Package for Potatoes,

was launched a year ago. Andrew Swallow asks two

growers who have bought the system what they think of it

A WORTHWHILE investment is how two growers describe the Management Advisory Package for Potatoes, a computer package which predicts and tracks potato crop development throughout the season, having bought into the system shortly after its launch last spring.

In Scotland, Sandy Bayne has used the package to track development of his 85ha (210 acres) of seed and pre-pack ware crops.

"We have used it to predict burndown dates and as an irrigation scheduling service. It tracks crop development well, but is very hungry for weather data," he says.

However, tapping into SCRI weather data from Dundee saved him having to record or make up his own figures for factors such as relative humidity or hours of sunshine.

"We learnt to copy and paste whole pages off the web-site into MAPP, then update the rainfall figure with our own."

Once seed rate, soil type, sowing date and variety data is entered the model predicts emergence date and crop development. Actual emergence date, if different, can be entered and the model continually updates crop development according to the weather experienced.

"Its ability to predict the start of tuber initiation, and when scab control irrigation should begin and end, is very useful," says Mr Bayne.

Tolerances for soil moisture deficit can be set according to the stage of crop development, for example maximum 18mm during tuber initiation and 25mm thereafter, he adds.

As crops approach burn-down dates test-dig data can be entered to make sure it is on track. If prices for different size fractions are entered it will calculate the economic optimum burn-down date.

"That is especially helpful as a seed grower. We might be selling four different grades of Maris Piper with a different price for each fraction, so it is a very complex calculation.

"The more effort you put into test digging the better result you will get," he adds.

Suffolk-based grower David Cargill also used the model to help target harvest dates with his 60-80ha (150-200 acres) of processing crop last autumn.

"Our sole objective was to use it as a financial guide as to how early we could start lifting – one day at the start of lifting is worth three at the end. It has been a good guide to do that."

Agronomists may use MAPP to model crops for clients, but Mr Bayne believes a hands-on approach is to growers advantage.

"To get the best out of it as a grower you want to have your own fingers on the keyboard, then you can run all sorts of "what ifs?" with it."

With eight different varieties on the farm that is helping fine-tune management crop by crop and it should easily pay for itself through increased output, he says. "An irrigation scheduling service for two crops alone would be over £300." &#42

&#8226 Improved irrigation scheduling.

&#8226 Helps target burndown date.

&#8226 Hungry for weather data.

&#8226 Hands-on use best.

&#8226 Worthwhile investment.

MAPPs original price package, a minimum 10-crop licence costing £1000 in the first year, has been made more flexible this spring, says project manager John Marshall of Mylnefield Research Services, the commercial arm of package developer Scottish Crop Research Institute.

The minimum package is now for three crops, costing £300 in year one and £150 a year thereafter. Each extra crop up to a total of 10 adds £100 in year one. Above 10 crops extra models cost £50 a crop and above 20 price is by negotiation.

"There is no limit to how many times you can put the data into the model and take it out again in what-if scenarios, but if you want to follow the crop through the season that is when the crop limit comes in." Another development is the provision of regional reference weather data from Dundee, Cambridge, Leeming in N Yorks, Shawbury in Shropshire, and Morley St Botolph, Norfolk, but local data is preferable, notes Mr Marshall.

Could a computer crop modelling package help tighten your potato management? Two growers who bought the MAPP package last year say it can.

More flexible pricing and reference weather data are new features for MAPP this spring, says John Marshall.