OCTOBER 2011 – WHAT’S UNDER YOUR GREEN?

Reading a soil profile

AS can be seen from the pictures, a soil profile has been removed from the green (picture 1, top) and illustrates the section down through the surface to approximately six inches deep with the cover removed as can be seen on the left of the picture.

Picture 2 shows a close up view of the soil profile. This provides a good example of the history of the green since the turf was laid. We can see what has been applied to the green from time to time and how the turf has risen from the original level of sea washed turf.

Starting at the bottom of the profile, which is below the silt layer, one can see there is not very good root zone material because it is composed of a mixture of clay and stones.

When constructed there was probably a very thin layer of sand all over and the sea washed turf, which should have been composed of sharp sand and the grass growing in it, was actually silt one inch thick.

The original problem was that the ideal sharp sandy soil that was used for the construction of bowling greens had been exhausted after more than one hundred years of cutting and supplying the country’s bowling greens.

So then the silt turf should have been top dressed with a suitable sharp sand material to integrate between the silt by the use of hand forks, hollow tine forks and solid tine forks. The aim of using the hollow tine would be to remove cores of the silt and integrate the top dressing of sharp sand to improve the structure.

However, we can see that in this instance no integration took place, with the top dressing forming later on the surface. Consequently, water couldn’t move through the surface of the silt because it is such a tight medium and almost waterproof. This meant that very little air and water were able to penetrate through for draining, resulting in a continuous moist surface for the bowlers.

As we move upwards from the silt layer we can see that for several years top dressing has been applied year after year and, as the different colours indicate, it has been sand from many different sources. There are also signs of composted materials and peat and seaweed mostly not decomposed due to lack of soil life.

I can only assume that they were led to believe that by adding top dressing at the end of every season they would attain a good playing surface, but as can be seen they were not solving the underlying problem, but just building the level of the green higher and higher.

As we get nearer the surface, say within two inches, there is very little sign of soil at all. It is mainly thatchy debris and sand from top dressings that would have been beneficial if integration had taken place.

Finally on the top there is mostly annual meadow grass with a few fescue and agrostis plants sitting on the thatchy debris.

Apart from the fact that there was a lack of spiking and aeration to integrate the levels of materials to form a good growing medium for fescues and agrostis, we can see the problems caused by insufficient cleaning out of the surface prior to seeding up and continuous top dressing for whatever reason.

A thorough cleaning out of the annual meadow grass (a weed grass) prior to over-sowing with the correct fescue and agrostis seed mix is essential for a good playing surface. To clean out the unwanted annual meadow grass and thatch debris you need to scarify without the blades touching the soil surface.

This scarifying will tease out the thatch above the soil and once the green has been cleaned out in one direction you need to change to a different direction and this can be done as many times as possible until you are satisfied that it is completely cleaned.

Only the annual meadow grass will be removed because its roots, which are thick and fleshy, mainly sit on the surface. All changes of direction of scarifying can only take place during the closed season. During the playing season all operations on the green must be undertaken on the diagonal only.

If inadequate cleaning out has taken place then an attack of fusarium is inevitable and the annual meadow grass seeds will have been scattered, easily germinate and if top dressing takes place the problem gets buried for another year.

If we wish to make a vast improvement to the soil profile shown we would firstly need to hollow tine down as far as the lower level of the silt to allow the water to penetrate below the silt into the original root zone.

Then during the winter carry out as much solid spiking and chisel tining as possible to aerate the soil and assist the water to move down to the lower levels of the green where it can be stored for later use in the summer.

The top surface should be kept clean by regular scarifying and unless there are undulations on the surface it should not be necessary to top dress at all.

Sisis Dart hitting bullseye for bowls club

THE Sisis Dart is hitting the bullseye at the Goodwood club in Leicester. Purchased at the end of last year to replace an older aerator that was so cumbersome the greenkeepers were reluctant to use it, the Dart’s ease of handling and vertical action have proved highly popular.

The club is one of the leading bowls venues in the county, benefitting from an excellent social programme, and as greenkeeper Tony Taylor points out, a top quality green.

“When we felt that the green needed some remedial work three or four years ago, we decided that the best course of action was to improve aeration and encourage healthy turf growth,” he explains. “We hired in a Verti-Drain and purchased a new Dennis FT510 mower that has interchangeable cassettes allowing it to be used for turf maintenance as well as grass cutting.”

The club also resolved to spike more often to tackle dry spots on the green, but the existing aerator made this difficult, so the greenkeeper approached the committee to put the case for a new machine.

Capital costs such as machinery have to be agreed by the committee so it was my job to persuade them,” he points out

A couple of different machines were considered, but another leading local club had a Sisis Dart, so a demonstration was arranged.

“It seemed to do the job, but, more importantly, it was so easy to use that I proposed that this was the machine to purchase,” he explains.

Powered by a 6.5hp engine, the Dart has a working depth of up to 100mm which can easily be adjusted from the operator’s position using the balanced depth control lever.

The unit can be fitted with a wide range of tines to meet the operator’s requirements. It gives clean, vertical penetration and withdrawal without surface disturbance – vital on the fine turf of a bowls green.

“We like the plunge action of the Dart – it works in a similar way to a tractor-powered aerator, and we use it either with pencil tines or with hollow tines from the old machine which also fit. It makes a really good, tidy hole,” adds the greenkeeper.