A field experiment was commenced in Bedfordshire during 1937, when soil infested with cysts of Heterodera schachtii was treated with very heavy dressings of calcium cyanamide. For comparison, a treatment with ammonium sulphate and lime was included. The lay-out was in the form of four randomised blocks of five treatments: control, calcium cyanamide 40, 60 and 80 c.p.a., and ammonium sulphate 80 c.p.a. plus hydrated lime 63 c.p.a. The last dressing contained the same amounts of nitrogen and lime as 80 c.p.a. of calcium cyanamide.