than a fork

31 January 1997

Probes more accurate

than a fork

UNTIL nearby Rendlesham Estate started using the neutron probe technique seven years ago the only way manager Harry Brown determined irrigation need was with a fork and his instinct.

"It was obvious a more precise approach was needed, although a fork is still a valuable tool for assessing water need," says Mr Brown.

"We did not use a potenti- ometer and felt the Irriguide system was not for us, as it involves too many subjective assessments of crop and conditions with many variables to go wrong. The probe seemed to be a step forward."

Main crops on the 360ha (900 acres) of arable on the light land estate are potatoes, sugar beet, oilseed rape and cereals. Over half the land can be irrigated by the three hosereels, and there is an extraction licence for 64m gallons. Crops irrigated include potatoes, beet, apples, blackcurrants and cereals on the sandiest soil.

"I use the probe in wheat and barley on the poorest land to provide the baseline for my cereals irrigation policy. Any deficit is corrected in April, so in May I can concentrate on scab irrigation in potatoes. There are four sites in the crop, which are checked weekly from before tuber initiation to the end of the season.

"The aim is to make the best possible use of water and apply just what the crop needs, I do not want to flush any fertiliser down the soil profile so it is beyond the crops rooting zone and out of reach," Mr Brown says. &#42


&#8226 Test sites in each field.

&#8226 Soil water content checked regularly.

&#8226 Computer calculates irrigation needs.

&#8226 Installation charge £60-70 a site, then £20-30/ha (£8-12/acre) for full service.

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