MATERIALS AND METHODS

Trial construction
The experimental area was originally constructed in 1981 and consisted of 250 mm medium-fine sand, overlying 50 mm coarse sand which formed a blinding layer above a 100 mm deep gravel drainage carpet. Full details of the construction are given by Canaway (1983). Since 1981 the area had been used for turf trials, the rootzone sand being periodically renewed to remove unwanted residual treatment effects. On 14 March 1990 the existing perennial ryegrass turf was stripped. On 15-16 March 1990 the upper 100 mm of the existing sand rootzone was removed and replaced with New Platt Wood sand. This was again a medium-fine sand with 91 % of the particles between 0.125 mm and 0.5 mm in size. The sieve analysis of the sand is given in Table 1; its pH was 5.6 and it contained 36 mg/l of P2O5 and 23 mg/l of K2O (0.5 M acetic acid extraction) indicating low levels of available nutrients.

TABLE 1

Category	Diameter (mm)	%
Stones	>8	0
Coarse gravel	8-4	0
Fine gravel	4-2	Trace
V. coarse sand	2-1	Trace
Coarse sand	1.0-0.5	4
Medium sand	0.5-0.25	53
Fine sand	0.25-0.125	38
V. fine sand	0.125-0.05	4
Silt + clay	<0.05	1

 

Particle size distribution of the rootzone sand (% by weight in each size fraction)

Seed bed preparation
The sand was allowed to settle for one month before final firming and levelling on 18-20 April 1990. 'Alginure' soil conditioner (a powdered seaweed extract) was applied at 50 g/m2 to aid moisture retention and also provide a supply of micronutrients. A proprietary fertiliser of analysis 20:5:8:2 (N:P2O5:K2O:MgO) was applied at 50 g/m2 to the seed bed. The fertiliser contained a slow-release form of nitrogen (IBDU) to reduce the potential leaching losses of nitrogen from the seed bed. Both Alginure and the fertiliser were raked into the upper 50 mm of the seed bed.

Experimental treatments
The experimental treatments, together with their abbreviations used in the subsequent Figures were as follows:
[1] Normal seeding (NL); [2] High rate of seed application (HR); [3] Coronet turf (CO); [4] mature turf grown on sandy soil (TSS); [5] turf grown on heavy soil (THS); [6] washed turf (WT).

The Coronet turf was delivered and laid on 23 April 1990 and the remaining plots laid or sown on 24 April. The experimental treatments were laid out in randomised blocks with five replications.

Trial maintenance
The aim was to encourage the turf to establish as quickly as possible with a target date for the start of wear c. four months after initial sowing or laying. Mowing was initially at a height of 25 mm and this was gradually reduced to the final height of 5 mm by 3 September.