First Things First
As a result of past geological events, the soils of Yorkshire are so diverse that a soil scientist can study more soil types in the county than in any other in Britain. They range from soils derived from the hard limestones and millstone grits of the Dales and Pennines, through to the pure white chalk of the Wolds and everything in between. Much of North Yorkshire was covered by ice during the last Ice Age, and the underlying rocks were covered by sediments laid down by glaciers. And since then, this skin of deposits – drift – has been further sculpted by rivers, lakes, wind and ice. Here in the Vale of York, the underlying rocks are cloaked in drift from glaciers, which has been carved and shifted by rivers, such as the Derwent and Ouse, laying down fertile mixtures of clay, silt and sand on their flood plains.
Too much information? Not really. Knowing your native soil is important because it is the main influence on the type of plants that can be expected to thrive in it; it also has implications for the way the soil can be managed. So when Beilby began this Jubilee Wood project, at the back end of 2010, one of the first things he initiated was an in-depth analysis of the soil in the area where we will plant Three Hagges Wood.
At depth, here, there are deep bands and pockets of occasionally pebbly sand, interspersed with bands of silt, clay and silty clay across the site. (There was even a sand pit at the southern boundary in 1851.) There are surface drifts of pure orange-red sand, and a rather fine silty grey soil that does not stick to the boots – so no clay there then. By contrast, in other places, there is dark brown sandy clayey topsoil that’s very sticky.
And beneath it all, there is a high level of groundwater that falls gradually into drainage dykes, eventually to find its way into the River Ouse. Even during the summer months, before this autumn’s heavy rains, soil water could be seen just inches below the surface in our inspection pit at the southern end of the site. We were convinced that such sandy, silty soil would be acidic, and prepared to adapt our plantings accordingly. But no, it’s actually near neutral, ranging from pH7 to a more alkaline pH 8, possibly because of the abundance of calcium compounds gypsum/ anhydrite in the parent rocks. That’s good news, it means it will suit a far higher range of plants than an acidic soil.
Perhaps it was too much to hope that we would be dealing with a soil that was the same right across the site. But then again, once we discovered the diversity of conditions, it seemed too good a chance to miss the opportunity of fine-tuning the planting to create several different habitats.
At the southern end of the site, where the land slopes slightly to the south/southwest, the ground is much wetter. So much so, that it will be eminently suitable for the birch and alder carr that will form our first planting. Just to the north of this stand, we will sow a grassland seed mix that will tolerate the wetter soils .
The remaining two-thirds become progressively drier, and better drained, and here we will plant sinuous stands of native trees and shrubs. The field layer on open ground between them will be sown with a grassland mix that will thrive in the floodplain soils are so characteristic of much of the land in the Ouse-Derwent catchment.