How do you decide whether it is getting too late to sow beet in southern regions?
While it is true that yield potential of fodder beet decreases as planting date increases, the yield achieved from planting a late crop of fodder beet can still be more profitable than switching to another option.
Research by DLF Seeds has found that a delay of one week in planting reduces yield by an average of 1.2 tonnes of dry matter per hectare (t DM/ha) (see graph below). If a farmer would normally achieve a 28 t DM/ha yield by planting on 25 October, they could expect a yield of 23.2 t DM/ha if it is planted on 22 November. If the costs to grow are the same, the cost of producing that feed has increased from 10 to 12 cents per kilogram of dry matter (c/kg DM).
If the paddock has been sprayed out or partly cultivated, a decision to no longer plant the beet crop will mean something else needs to be planted. Of course, if an alternative crop type is chosen, its yield will also be less than normal due to the late planting. Some crop species are quite quick to reach their full yield (e.g. turnips, rape and forage brassica), but that final yield will not be anywhere near that of a fodder beet crop, even if it is planted later than normal.
Other brassica crops with a longer time needed to reach final yield could be considered (e.g. swedes or kale). However, they will also have lower yield potential by being planted late. For example, a kale crop planted on 22 November may reach 8 t DM/ha by winter, but with average growing costs of $1000/ha the cost of that feed is 12.5 c/kg DM. As fodder beet is utilised at a higher rate than kale when grazed and has higher feed quality, fodder beet will still be a more profitable crop than kale when planted late in the spring season.
Also, many farmers will require a large amount of feed from a paddock in winter, so switching to a lower-yielding crop type will make feeding animals next winter very difficult.
If December is also wet, there may still come a point in time where the beet crop is not worth planting. Fortunately, the loss in yield potential for each week of delay in December is less than that in November due to warmer temperatures, which accelerates the growth of beet crops. A fodder beet crop planted on 20 December would be expected to yield about 8 t DM/ha less than one planted 25 October, achieving a typical yield of 20 t DM/ha by winter, at a feed cost of 14 c/kg DM. This is still cheaper than most other ways of feeding animals over winter.
Therefore, in most cases, farmers are advised to still plant their fodder beet crops through to at least the end of December.