Relationship of Nitrate Accumulation to Yield Response of Wheat in Some Saskatchewan Soils

The capacity of Saskatchewan soils to accumulate nitrate, as determined by a laboratory procedure, was investigated as a method for evaluating the response of wheat to nitrogenous fertilizers. The correlation coefficient between the field yield ratios (which are a measure of the response to nitrogen) and nitrate accumulation for 31 stubble fields was 0.846** and for 30 fallow-soils was 0.830**. Greenhouse experiments with soil samples from 31 stubble fields showed a high correlation (0.874**) between nitrate accumulation and nitrogen uptake by wheat plants during a 30-day growth period.It is considered that a significant increase from the application of nitrogenous fertilizers can be expected when the nitrate accumulation value is below 50 p.p.m. N in soil from stubble fields or 40 p.p.m. N in fallowed soils.