Corn with FAO 140 hay in June. How does it compare to the rest?

Kukurydza o FAO 140 siana w czerwcu. Jak wypada na tle pozostałych?

The FAO number gives flexibility

Corn varieties available in Poland range from FAO 130 to just above 300. The higher the FAO number, the later the variety is, and therefore the longer its growing season. Each "ten" more in the FAO number means approximately 10 days longer vegetation for a given variety.

The FAO number of corn varieties is related to the sum of effective temperatures, i.e. "heat accumulated" during plant vegetation. Depending on the earliness of the variety, the sum of effective temperatures necessary to move to subsequent development phases differs. Earlier grain and silage varieties require a smaller sum of temperatures to reach ripeness for harvesting, and later "grain" varieties – a higher sum. Hence the differences in the number of growing days – it is necessary to "accumulate" the appropriate sum of degree days.

The regionalization of corn cultivation in Poland is related to the number of FAO. In areas with better climatic conditions, more favorable for corn, such as the southwestern part of the country, you can afford to grow later varieties, which are also more fertile. In the north of the country or in a mountainous region, less suitable for growing corn, it is safer to choose varieties with a lower FAO count.

As mentioned, later varieties of corn yield better, but they reach maturity later, which may prove problematic in unfavorable autumn. In turn, early varieties are usually less fertile, but they provide greater certainty of reaching maturity at the appropriate time and allow for a relatively quick harvest of grain with optimal moisture content or silage with the desired dry matter content.

Early and very early varieties can be used when corn sowing must be delayed for various reasons. They are often used when screening a damaged plantation (e.g. after a hailstorm). Thanks to the shortened growing season, they can be harvested within a standard time. Extremely early varieties (FAO 130-140) can also be used, for example, as a catch crop for silage.

When to mow corn for silage?

Very early corn from late sowing in Greater Poland

We encountered the situation described above on one of the corn plantations in the province. Greater Poland. Unfortunately, the previously established crop required liquidation and reseeding. Due to the date – the beginning of June – it was decided to sow corn with FAO number 140, i.e. a very early variety. Probably slightly later varieties, e.g. FAO 180, would also be able to cope with this sowing date, but they were simply no longer available for sale at that time.

Greater Poland as a region is characterized by low average annual rainfall and repeated periods of severe droughts. In such conditions, late, June sowing of corn carries a high risk of failure. In 2024, however, the weather was more favorable, which worked to the plantation's advantage. From sowing the corn through the next stages of development, it rained quite regularly.

Most plantations in this location were established in the traditional period from the end of April to the first days of May. Therefore, the low FAO maize we examined was sown a month later than the standard date. Importantly, however, it quickly "balanced" its development phases to corn sown in May. This was facilitated not only by the availability of water, but also by heat, thanks to which the plants quickly accumulated the necessary sum of effective temperatures to achieve subsequent development phases. To illustrate how the very early variety "caught up" in development – despite the monthly difference in the sowing date, it flowered about 10-14 days later than the plants on the other plantations. This allows us to predict that it will be suitable for harvesting for grain at a similar date to other corn, without the need to delay mowing and, therefore, without being exposed to unpredictable weather conditions.

Is this very early variety from June sowing different from other plantations? Despite the universal use of this variety, the plants have slightly less leaves, have quite low-set cobs and are lower than other corn plants, although their height is satisfactory and exceeds 200 cm. These properties may not only be the result of the sowing date, but also result from individual characteristics and the genetics of the variety. It can be assessed that pollination has taken place properly, cobs and kernels are developing. Unless conditions deteriorate dramatically, the cob should be filled with well-developed kernels. Compared to other plantations, in this case there are slightly fewer rows of grains in the cob and fewer seeds per row.