Establishment Studies. I. The effect on spring oats of undersowing with a one-year ley

Abstract

A field experiment was carried out to study the effect on spring oats of undersowing with broad red clover, Italian rye-grass and a mixture of both. Two levels of nitrogen were used, namely, no nitrogen and 3 cwt. per acre of ‘Nitro-Chalk’.1. Oat shoot weight was reduced by undersowing, Italian rye-grass having a greater effect than red clover, particularly where nitrogen was applied.2. In the absence of nitrogenous fertilizer undersowing did not reduce oat plant height, but where nitrogen had been given, Italian rye-grass either alone or in a mixture with the clover, reduced the height; the legume alone had no effect.3. Undersowing generally reduced the number of oat panicles. Italian rye-grass had no effect when nitrogen was not applied, but a marked reduction was observed when nitrogen was applied. The legume had the greater influence where nitrogen was not applied.4. Red clover increased the number of whorls, and the number of single-grained spikelets per panicle. Grass sown alone or with clover reduced the number of single-grained spikelets per head.5. The total number of grains per panicle, 1000 grain weight, percentage husk and the percentage of saleable grain were not influenced by undersowing.6. No lodging occurred but there was an indication that resistance to bending of the straw was affected by undersowing with Italian rye-grass.7. Seeding herbage under the oats had a bigger influence on the yield of straw than grain. Italian rye-grass sown alone or with clover reduced the yield of straw where nitrogen had been applied. The legume alone had no effect. Grain yields showed a similar trend.8. Yield and percentage crude protein in the straw were reduced by Italian rye-grass alone or in a mixture with clover when nitrogen was applied, but there was no effect where nitrogen was withheld. The grass had a greater effect than red clover while a mixture of both was intermediate to the legume and grass sown separately. Italian rye-grass greatly reduced the recovery of applied nitrogen by the cereal.9. The percentage moisture in the oat sheaves was increased by undersown herbage and red clover had a bigger influence than the grass. The application of nitrogen reduced the bulk of clover under the cereal and its adverse influence on the harvesting of the oats. In the absence of undersowing, nitrogen had no effect on the percentage moisture in the sheaves.