Summer Brassicas

Using summer brassicas to secure your summer feed supply

Brasiccas are a great way to bridge the gap before maize is ready to be harvested, providing a bulk, high protein feed. Summer turnips have always made a valuable contribution to pasture renewal programmes. After this season’s experience, Owl Farm, St Peters School’s demonstration farm near Cambridge, has a better understanding about how important summer turnips are, particularly in a tough, dry season.

Owl Farm planted both Cleancrop™ Bulb Turnip (80-110 days maturity) and Cleancrop™ Toto turnip, a new variety from PGG Wrightson Seeds, which has been bred to be an early maturing, high yielding summer turnip (55–90 days maturity). Planting both turnip cultivars on the same day gives a variation in spread of maturity, whereby the turnips can be grazed over a longer period. This also reduces the need to drill turnips a few weeks apart, as there already is almost a 3-week difference in maturity.

Owl Farm also planted their first kale crop this season at just under three hectares (ha). Cleancrop™ Firefly kale was planted midOctober, not as a winter feed for dry cows, but rather to provide milkers with a high-quality feed in March after they had finished the turnips.

Dairy cows were moved straight from turnips onto kale, since no transition period is required between brassica types. “The use of kale greatly extended our brassica-feeding ‘window’ with cows staying on brassicas for a longer time than if we relied on turnips alone” says Tom Buckley, Farm Manager at Owl Farm.

Owl Farm staff are pleased with the results from their summer brassicas. “We wanted to get the best value out of the crop,” says Jo Sheridan, Owl Farm’s Demonstration Manager. “Producing a good crop costs as much as a poor crop, so it was important we looked after the crops to maximise yield. In this extremely dry year we have discovered how important it is to select the paddocks that are most suited to the crop, rather than just focusing on the paddocks that we are going to renew.”

Maximising yield is important to dilute the fixed costs (for example, drilling, fertiliser and crop protection etc.). Growing a cultivar that maximises yield in a short timeframe, such as Cleancrop™ Toto, that maximises yield in a short period of time is a great way to reducing the cost per kilogram of dry matter (kg/DM). The crops were yielded on the 17th of December 2019, 55 days after sowing, and interestingly Cleancrop™ Toto had yielded just over 10 tDM/ha, while Barkant turnip had only yielded around 8 tDM/ha (in the same paddock).

“Even with the extremely dry conditions this summer the crop was valuable”, says Tom. “We managed to get eleven weeks of feed out of our eleven hectares of crop, that was 3 kgDM/ cow/day from crops that yielded, on average, 10 tDM/ha.”

Kyle Gardyne from PGG Wrightson Seeds mentioned the combination of turnips and kale have proven a good choice for Owl Farm, “you can use brassicas to build a feed bank coming into January/February/March when you require extra feed. Using the two turnip cultivars to spread maturity, then getting an extra few weeks of feed from the kale has been a great way to push summer brassicas out into mid-March”.

“Other crops, such as chicory, can be a little more reliant on moisture for post-grazing regrowth, so even though the turnip and kale yields were a couple of tDM/ha less than Owl Farm’s previous season average for turnips, and lower than our expectations for yield from the kale, this crop combination still proved to be better off in terms of bulk feed during this extremely dry season.”

Owl Farm carried out further research into the cost per kilogram DM of this season’s brassica crops. It was found that to establish and grow the turnip and kale crops cost 15.9 c/kgDM.

An additional step to this analysis was the opportunity cost of removing pasture from the feed supply.

“We lost the productive potential of growing pasture in the crop paddocks between October

Cleancrop Toto Turnip (Left) vs. Barkant Turnip (Right)