The construction, irrigation and fertiliser nutrition of UK golf greens
A field trial was established of a mixed grass sward grown on three types of golf green construction. These consisted of a topsoil, a sand, peat and soil mixture, and a pure sand. Experimental treatments applied were three levels of irrigation, five of nitrogen fertiliser and two of phosphate. The trial was maintained as a golf green, and artificial wear was applied. Soil moisture deficit predictions by the Meteorological Office conformed with measurements from the soil construction, but the sand-based construction types showed higher deficits. The overall rate of evapotranspiration was around 65 % of predicted values. Pore structure of the sand-based rootzones changed slowly over time, but water infiltration rates fell markedly. The soil constructions showed a reduction in the proportion of larger pore spaces in the top of the profile, and infiltration rates were consistently low. Plant death was associated with both high and low rates of nitrogen fertiliser, low rates of irrigation, and was especially apparent on the sand constructions not receiving phosphate fertiliser. Ingress of the weed species Poa annua (L.) occurred mainly on the soil constructions and its rate of ingress was enhanced by increased nitrogen input. Golf ball roll and various aspects of their behaviour after impact onto the turf with simulated 5-iron flight characteristics were measured. Roll length declined with increasing fertiliser rate. Hard greens produced long, high bounces and shallow pitch marks. High rates of both irrigation and nitrogen produced deeper pitchmarks and were associated with the tendency of balls to "screw back". A multivariate method of classifying the quality of golf greens on the basis of a small number of objective measurements was developed. The classes of greens derived were described in terms of their average visual merit, green "speed", bail behaviour after impact, and the treatment factors which they had received.