VAT on labour for self employed

Hi ,

      I have been advising a self employed friend on whether or not to register for VAT .

      This would be a voluntary registration as he is currently below the threshold .

      His prime business is Hedge cutting , usually around farmers fields but this also includes other

      general farming work , for example , sowing and harvesting .

      The work can involve using his own tractor but sometimes not .

      My question is , if he did register for VAT , and the fact that most of the invoice would be "labour time" ,

      would the labour element be chargeable for VAT ?

      Thanks Kevin