Nitrogen and Herbage Production*

A plot experiment is described in which the direct effects of and the interactions between two of the main sources of nitrogen for grassland, namely clover and fertilizer nitrogen, were measured. The results demonstrated the value of both clover and fertilizer nitrogen in raising yields and showed that these two sources of nitrogen had a marked additive effect on yield in at least the first two years of the experiment. The practical implications of these results are discussed with reference to the results obtained on a field scale on the Institute's farm. Possible methods of combining the use of clover and fertilizer nitrogen within a fanning system are considered.