Phosphate uptake and dry-matter yield from unfertilized pots and relative yield (ratio of unfertilized to fertilized yield) of Rhodes grass were used as plant indices of P supply from twenty-four soil samples from long-term manurial trials in Nigeria. Although measurements of the soil P quantity factor were generally the more important, intensity measurements also made a highly significant independent contribution to the P supply. Inorganic P (a quantity measure) combined with the log of P concentration in a saturation water extract (an intensity measure) gave a multiple correlation coefficient of R = 0·954*** with relative yield, accounting for 91% of its variation. The best single measure was resin-extractable P, which gave r =0·930*** for correlation with relative yield. Organic P did not appear to contribute to plant growth.

Seven commercial barley varieties were inoculated with mycelial suspensions of different isolates of Gescosporella herpotrichoides. There were significant varietal differences in eyespot susceptibility. There were significant differences between isolates which originated from both wheat and barley. The yield of the varieties was reduced between 30 and 50% depending upon the isolate used. Significant interactions between isolates and varieties were found for the incidence of disease, its effect on tiller number and upon total yield.

An experiment was carried out over a 5-year period on a grass/clover sward at North Wyke to compare three methods of experimental management—individually grazed plots, communally grazed plots and cutting with removal of herbage. Responses to phosphate and potash fertilizers under each management were measured.

P fertilizer increased grass yields in the first 4 years and decreased clover yields in the last 2. In almost all respects cut and grazed sward responded similarly to P. Fertilizer K had no effect on grass yield but markedly increased clover yield and raised herbage K content. Grazed swards developed a higher herbage K content than cut swards, and K fertilizer increased it more in the fourth and fifth years on the individually grazed than on the communally grazed plots. Thus communal grazing resulted in appreciable transfer of K from plot to plot in animal returns.

It is concluded that whilst cutting management may be used for short-term experiments, its use in long-term experiments gives different results from grazing. Communal grazing can lead to the transfer of N and K effects from plot to plot, so that plots must be grazed individually except perhaps where P is the only variable nutrient.