Turnip

Six to ten weeks from sowing to a usable root lets turnip occupy ground that would otherwise be bare: after an early cereal, before a spring crop, or in a gap left by a failure. Almost every agricultural use of the crop follows from that window rather than from yield per hectare.

Fertilizer rates, timing, and forms should follow local soil tests and regional guidance. AgricultureID does not publish universal fertilizer recommendations.

The Norfolk four-course rotation put a root crop between cereals, and turnip was the root: it produced winter feed on land that had carried grain, it was grazed in place so the manure stayed in the field, and it broke the cereal disease and weed cycle. That is a rotation argument rather than a crop argument, and it is still the argument for growing it.

Management combines resistant varieties, rotation, monitoring, and — where justified — locally authorized control products applied according to their labels.

Stubble turnips are commonly eaten in the field by sheep or cattle behind an electric fence rather than lifted, which removes harvest and haulage entirely. The costs move to fencing, water and the risk of poaching wet ground, and the crop is chosen partly because those costs are lower than a harvest.

Turnip is biennial and flowers after vernalisation, so a crop sown too early into cold conditions can run to seed instead of filling a root. Sowing date is therefore bounded at both ends — late enough to avoid vernalisation, early enough to bulk before winter — and the window is narrower than the crop's speed suggests.

Swede is Brassica napus, an amphidiploid of B. rapa and B. oleracea, with a longer season, a denser yellow flesh and far better storage. Turnip is faster and does not keep. English usage confuses them and Scottish usage reverses the names, so a record naming either has to be resolved before it can be used.

Clubroot swells and distorts brassica roots and its resting spores persist in soil for many years, so a turnip crop is a decision about a field's brassica history and its future. In rotations that already carry oilseed rape or brassica vegetables, adding turnip concentrates the pressure rather than diluting it.

Brassica rapa also carries chinese cabbage, pak choi and the oilseed turnip rape, and the infraspecific classification of the species is contested between treatments. What is not contested is the agricultural forms: a turnip is a turnip whether the treatment calls it a subspecies or a cultivar group.

Turnip leaves are eaten as greens across the American South, southern Europe and East Asia, and in fodder systems the tops are a substantial share of the feed value grazed. A yield figure for roots alone understates what the crop produces.

The crop wants a firm, moisture-retentive seedbed and does poorly on cloddy ground where the root forks. Where it is lifted rather than grazed it is handled like any thin-skinned root: bruising shows, and storage life is short compared with swede.

Soil suitability should be assessed with local soil survey information and, where available, field testing.