Soil and drainage in a cider orchard

Apple roots respire, and respiration needs oxygen. In a saturated soil the pore spaces that normally hold air are full of water, oxygen diffuses roughly ten thousand times more slowly through water than through air, and the roots suffocate. A few days of saturation in the growing season will damage fine roots; prolonged winter waterlogging will kill them outright and leave a tree that leafs out weakly in spring and dies back over the following two seasons.

The visible symptoms are unhelpfully vague — poor extension growth, small pale leaves, early autumn colour, dieback — and they are easily mistaken for nutrient deficiency, which leads growers to fertilise a tree that is drowning. The diagnostic step is a hole: dig a pit in the wettest part of the orchard in late winter, look for a water table, look for grey-blue mottling in the subsoil, and look at where the roots stop.

Waterlogging also invites Phytophthora species, which cause collar rot and root rot and are far more damaging on wet ground. MM106, the workhorse rootstock of English bush cider orchards, is notably susceptible to collar rot, which makes the drainage question specific rather than general: on a wet site MM106 is a poor choice regardless of how well it performs elsewhere.

Rooting depth sets drought resilience. A tree with a metre and a half of usable soil will ride out a dry summer that stresses a tree on sixty centimetres over rock or a compacted pan. In an unirrigated cider orchard — which is most of them — that reserve is the whole of the drought strategy, and it is the argument for planting standards on deep ground and treating shallow soils as bush-orchard land where irrigation is at least conceivable.

Texture governs both drainage and workability. Sandy and loamy soils drain freely but hold less water and less nutrient; heavy clays hold plenty of both but drain slowly and compact badly under machinery. Most of the classic English cider ground is a medium loam over permeable subsoil, often over sandstone or river gravels, which is exactly the combination that gives both depth and drainage.

Compaction is the modern version of the drainage problem. A bush orchard alley carries a tractor many times a season, and repeated traffic on wet ground produces a pan that stops water moving and roots growing. It is a manufactured drainage failure on soil that was originally fine, and it is much easier to avoid than to remedy.

Apples tolerate a fairly wide pH range and are usually content between about pH 6 and 7 in mineral soils. Extremes matter more than the precise figure: strongly acid soils lock up phosphorus and calcium and mobilise manganese and aluminium, while strongly alkaline soils induce iron and manganese deficiency and show it as interveinal chlorosis. Liming and its opposite are slow corrections and should follow a soil analysis rather than an assumption.

Nitrogen is the nutrient with the most direct consequence for the finished drink, and it works in both directions. Too little and the trees grow poorly and the juice arrives at the mill short of assimilable nitrogen, which is a leading cause of sluggish and stuck fermentations and of sulphidic aromas in the vat. Too much and the trees make vegetative growth at the expense of fruit bud, the fruit is larger and more dilute, and the canopy is denser, wetter and more disease-prone.

Low-input traditional orchards sit firmly at the deficient end. This is one of the clearest cases where an orchard decision reappears at the fermentation bench: a maker pressing fruit from an unfertilised grazed orchard should expect low nitrogen in the juice and plan for it, rather than discovering it when the ferment stops at a third of the way down.