Field Emergence

Emergence is the reality check on everything else in this category. It is measured after the fact, by counting what came up and dividing by what went down, and it is the single most valuable number a grower can carry from one season into the next — because it is the term in the seeding-rate equation that nobody else can supply for your field.

Sow 400 seeds per square metre, count 320 plants at the three-leaf stage, and emergence is $320/400 = 80\%$. That is a good but ordinary result for a spring cereal; 85 to 95% is what a firm, moist, warm seedbed returns, and 60% or less says something went wrong that a higher seeding rate will paper over rather than fix. The count has to be of established plants, taken late enough that the stragglers are up and early enough that nothing has died, which in practice means the two-to-four-leaf stage.

The classic mistake is counting stems. A cereal plant at tillering carries three to six stems, and a count of stems divided by seeds sown returns a number above 100%, at which point the arithmetic is telling you something is wrong with the count rather than something remarkable about the crop. Dig a few up if you are unsure — tillers share a crown, and the difference is obvious once you have seen it. The second mistake is comparing a plant count against the seeding rate in kilograms rather than in seeds, which reintroduces the thousand-kernel weight as an unstated assumption and buries whatever the seed lot actually was.

When emergence disappoints, the causes come in a fairly reliable order. Seeding depth is first and is usually too deep, because a drill set for 25 mm in a firm seedbed runs at 45 mm in a soft one. Seedbed moisture at the placement depth is second. Soil temperature is third, and it acts by lengthening the time the seed spends vulnerable rather than by killing anything outright. Crusting after a hard rain on a fine, bare seedbed is fourth and is the most brutal, because a crop can be lost between germination and emergence with no visible seedling to explain it. And seed-placed fertiliser is fifth, entirely avoidable, and the one that catches growers who moved to a narrower opener without recalculating the safe rate.