Experimental Investigations into the Mineral Nutrition of Several Grass Species: Part II. pH and Calcium Level

Abstract

In two previous papers (Bradshaw et al. 1958, 1960) investigations have been described of the response of several grass species with contrasting ecological preferences to calcium level and pH in sand and water culture. Considerable differences in the nutrition of these species have been shown, throwing light on their ecology. The investigations have been continued in order to determine the effect of variations in phosphate level both alone and in combination with varying calcium level, using the sand-culture technique described by Bradshaw et al. (1958). Besides the seven species previously used, an eighth, Festuca ovina, was added in the hope that its behaviour might be compared with that of Agrostis tenuis, with which it is normally associated. It has recently been shown (Bradshaw & Snaydon 1959) that there is marked differentiation within Festuca ovina with respect to its calcium nutrition. Material was therefore taken from an acid upland area, Mynydd Llandegai, near Bangor, Caerns., whose nutrition is known to be similar to that of the acid population previously studied, and thus comparable with Agrostis tenuis. In order to compensate for the considerable differences in growth rate of the species, and to attempt to ensure a more uniform quantity of plant material per pot, Nardus stricta, Festuca ovina and Agrostis canina were represented by three plants per pot, while the other species were represented by two. Phosphorus is an essential plant nutrient, the amount and availability of which varies considerably from one soil to another. It is well known that species differ considerably in their reaction to the supply of soil phosphorus. It appears that the reaction of species depends either on their overall phosphate requirements or on their ability to obtain phosphorus from the less soluble forms of phosphate in the soil. These two characteristics are not necessarily correlated (Russell 1950). A considerable amount of work has been carried out on interspecific differences in the ability to obtain phosphorus from the less accessible phosphate (Thomas 1930, Black 1957, Russell, Russell & Marais 1958 and others). Although it seems