The value of calcium nitrate for spring-sown cereals

Abstract

1. Seven experiments on spring barley and five on spring wheat carried out in 1955–7 compared dressings of ammonium sulphate and calcium nitrate applied to the seedbeds at 0·3 and 0·6 cwt. N/acre. The fertilizers were tested both when broadcast and when drilled with the seed.2. Consistently higher yields of barley were produced by drilling than by broadcasting ammonium sulphate. Drilling calcium nitrate at 0·3 cwt. N/acre was superior to broadcasting for barley but when applied with the seed at 0·6 cwt. N/acre this fertilizer retarded germination and early growth and gave smaller yields than were obtained by broadcasting. Broadcast dressings of both fertilizers gave higher yields of wheat than combine-drilled dressings. There is a considerable risk of fertilizer ‘scorch’ when compound fertilizers containing all their nitrogen in nitrate form are combine-drilled at rates sufficient for maximum yield. This risk may be discounted when adequate rain follows drilling but the check to germination may be sufficient to reduce yields in dry springs, on light soils, and on badly prepared seedbeds. Fertilizers containing all their nitrogen in ammonium form appear to be quite safe at the rates of dressing tested in this work.3. Calcium nitrate and ammonium sulphate gave similar yields and nitrogen contents of both crops when the fertilizers were broadcast on the seedbed. Nitrates applied at sowing-time to cereals grown in the drier parts of the country do not appear to be leached out of the root-zone before they can be taken up by crops.