The comparative value of calcium cyanamid and ammonium sulphate on the yield of Irish potatoes on Bladen Fine Sand

Summary

• 1. Calcium cyanamid produced no injurious effects on potatoes when mixed with the soil two, four and six weeks before planting, even when applied at the rate of 492 pounds per acre. An application of 900 lbs. per acre produced no injury under greenhouse conditions.

• 2. Calcium cyanamid produced better yields of potatoes (20 bushels per acre) than did equal amounts of ammonia from ammonium sulphate. Moreover mixtures of calcium cyanamid and ammonium phosphate gave better yields than did mixtures of calcium cyanamid, sulphate of ammonia and superphosphate.

• 3. Dolomite and gypsum used in conjunction with ammonium phosphate mixtures increased the yield of potatoes with virgin soil under greenhouse conditions, but had little or no effect on the yield in fields which had previously been fertilized.

• 4. An increase in calcium cyanamid increased the yield of potatoes, also the pH value and replaceable calcium in the soil, while an increase in ammonium sulphate decreased the yields, pH values and replaceable calcium.