Sewage sludge suppresses take-all

4 June 2001



Sewage sludge suppresses take-all

By FW staff

APPLYING sewage sludge before a second wheat crop can lift gross margins by suppressing devastating cereal root disease take-all, claims a crop consultant.

Peter Taylor, who operates in Essex and Herts, decided to investigate when clients reported surprising results after Terra digested sewage sludge was applied.

Second wheats treated this way yielded on a par with, and sometimes above, first wheats, despite mineral fertiliser rates having been slashed by up to 50kg/ha.

Yield benefits were even observed where the organic manure was applied earlier in the rotation, said Mr Taylor, an independent consultant.

This discovery followed the increased use of Thames Waters sewage-based Terra Cake as growers looked for cheaper sources of P and K, said Mr Taylor.

We were expecting to see a financial advantage from lower mineral fertiliser rates, but the yield benefits have been far greater than we imagined.

On our heavier soils there are limited slots for applying sewage sludge in the rotation, such as oilseed rape, hence our interest in applying it for second wheats.

Mr Taylor believes the use of organic sewage sludge counteracts the effects of take-all, although there is no scientific proof.

The most likely cause is the balanced and continuous nutrient supply to the growing crop, in particular the availability of phosphate and nitrogen, he suggests.

In 1999 sludge-treated second wheat on one Herts farm yielded on a par with first wheats.

The following year sludge-treated second wheat Rialto yielded 5% better than the same variety grown as a first wheat on an identical soil type.

Both results were despite second wheats receiving no mineral P and K and 40-50kg/ha less nitrogen.

• Sewage sludge a safe bet?, FWi, 20 October 2000
• Farmer loses in sludge scare fight, FWi, 01 June 2001
• Farm bodies fall out over sludge, FWi, 07 January 1999
  

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