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The influence of fungi isolated from perennial ryegrass roots on the germination and development of seedlings of perennial ryegrass was investigated. The basic procedure employed was to sterilise the seed surface and then inoculate with fungi and plant in non-sterile soil. It was realised that the fungal isolate inoculated on to the sterile seed surface would not remain dominant in the root region of the host and would have an influence on the host which would decline with time from when the seed germinated. This was because it would have to face antagonism from the normal components of the root microflora present in the non-sterile soil. Trichoderma viride delayed the emergence of the seedlings and reduced the production of herbage, an observation consistent with results of some other investigators. A sterile hyaline fungus stimulated the emergence of the seedlings, but subsequent tests showed that the presence of the microflora of the seed coat, or the soil microflora, or the sterile hyaline fungus was effective in promoting the rate of germination of seed that had been surface sterilised. Leaching seed in water brought about an increase in the rate of seed germination, and it is suggested that there might be a germination inhibitor soluble in water present in the seed coat, which might be inactivated by saprophytic micro-organisms. [ABSTRACT FROM AUTHOR]

The effects of applications of urea and ammonium nitrate on the growth and foliage yield of maize were compared in a series of pot experiments. The factors studied were; rate, form, method and time of application. It was concluded that above a threshold value (approx. 300 mg N/pot) urea was inferior to ammonium nitrate and that the factors affecting the efficiency of urea were soil type and also rate, method and time of the application. Physical form of the urea had no effect. [ABSTRACT FROM AUTHOR]

The inefficiency of base-dressing applications of urea relative to ammonium nitrate was examined in a series of pot experiments using a sandy-loam soil (pH 7.4) and maize as a test crop. The results of the experiments demonstrated: [ABSTRACT FROM AUTHOR]

In a series of pot experiments the effect of soil applications of urea on the aerial growth of various crops was compared with that of ammonium nitrate and ammonium sulphate. When the nitrogen sources were uniformly incorporated in the soil at the time of sowing the pattern of response was essentially the same for the twelve crops examined. Applications of urea, ammonium nitrate and ammonium sulphate at the lowest rates gave similar yields. At the intermediate rates, yields from urea were considerably lower than from the other nitrogen sources and were often equal to or less than those of the no-nitrogen controls. At the highest rates of application, urea gave much lower yields than the other sources. In most crops these smaller yields were associated with urea-induced damage which was followed by the death of established plants. Topdressing applications of urea and ammonium nitrate caused very slight damage and increased the yields of all five crops. The responses from urea were lower than those from ammonium nitrate, especially at the higher rate of applied nitrogen. However, within each method of nitrogen application, the pattern of response to urea was similar for all the crops tested. Maize was selected as a suitable indicator plant for potential investigations on the effects of urea as a fertilizer. [ABSTRACT FROM AUTHOR]