An investigation into the absence of sulphur and phosphorus responses in the dryland lucerne at Ashley Dene : a dissertation submitted in partial fulfilment of the requirements for the degree of Bachelor of Agricultural Science (Honours) in the University of Canterbury [Lincoln College]

In recent years, attention has been focussed on the efficient use of fertilisers in New Zealand. Superphosphate has become an expensive farm item as a result of continuing demand and higher production costs. In terms of the correct supply of nutrients required by pasture species, the use of superphosphate has been inefficient on many soils. This has been indicated by recent fertiliser trials in New Zealand as reported by During (1972). The continual application of superphosphate to many soils has increased their level of plant available phosphorus (p) to the extent that superphosphate could possibly be withheld for several years, provided sulphur (S) requirements are met. The efficient use of S and P fertilisers therefore demands a sound knowledge of the S and P status of the soils and the pasture requirements. The key to improvement of shallow stony soils in Canterbury has been the introduction of lucerne. This has been associated with the continual application of superphosphate for several years, resulting in a build up of the S and P status of these soils. However, little is known of the residual effect of these continued applications of superphosphate on the available S and P pools. The present study attempts to achieve this objective in a dryland lucerne situation on an Eyre soil. The effects of different rates of S and P on plant parameters were recorded and related to the levels of S and P fractions in the soil