Results from two sets of experiments with spring barley, the first comparing injected with broadcast nitrogen granules, the second comparing injected and combine-drilled NPK solutions with broadcast NPK granules

Summary

Six experiments from 1969–71 compared yields of, percentages of N in, and removals of N by barley given 63 or 126 kg N/ha either as urea or as ‘Nitro-Chalk’ which were either broadcast or injected into the seed bed. Both fertilizers were equally effective and each gave a slightly larger yield when injected.

Eleven more experiments compared yields of, percentages of N in, and removals of N by barley given either NPK solution fertilizers or NPK granules supplying 63 or 126 kg N/ha. One liquid (14–6–8) supplied the whole of the N and was either sprayed, combine-drilled or injected mid-way between the seed rows (15 cm apart). The other liquid (4–10–10) supplied one-fifth of the N and was either combine-drilled or injected; ‘Nitro-Chalk’ supplied the remainder of the N. The granular fertilizer (20–10–10) was broadcast.

The 14–6–8 solution always gave a smaller yield than comparable granules. Yields with injected dressings were no larger than with sprays, but each was safe. Combine-drilled dressings were harmful and often killed the barley and decreased yields especially when 126 kg N/ha was given.

The 4—10–10 solution was harmless when combine-drilled and gave a larger yield than the granules when 63 kg N/ha was given and the same yield when 126 kg N/ha was given. It gave a smaller yield than the granules when it was injected.

Grain percentage N tended to be larger with the injected liquids and smaller with the sprays than with the broadcast granules though the amount of N recovered by the barley from the injected liquids was no larger than from the granules.