Any soil structure, drainage or base fertility problems should also be addressed before sowing, or avoided through paddock selection.
“All high performance forage crops need adequate pH – 5.8 or above – to grow well.”
Low phosphate is unlikely to limit crops in a dairy situation but they are big users of nutrients so phosphate, as well as nitrogen fertiliser, is usually applied.
Fertiliser nitrogen requirement should be calculated from expected yield and soil supply. Cultivation releases a flush of nitrogen so crops sown in worked paddocks may need less upfront than those direct-drilled.
Whatever the establishment technique, with turnips and rape no nitrogen should go on after canopy closure to avoid raising toxicity risk at grazing, Nichol warns. For repeat graze crops, such as chicory or plantain, a little nitrogen immediately after each grazing is the best approach.
Where crops are going in straight after grass he recommends two burn-down sprays before direct-drilling. If cultivating, ideally spray-off then cultivate. A pre-emergent herbicide might be needed too.
“Once the crop is up weed control becomes a lot harder and more costly, particularly if you’ve got mixed species such as chicory or plantain with clover.”
Herbicides should be tailored to the local weed spectrum and the planned crop, and selected so they won’t compromise grass or whatever is to follow the crop.
Pest pressure at emergence is reduced by cultivation but protective seed treatment should still be considered to be sure of getting a good stand, and it’s a must when direct-drilling, Nichol says.
“You might want to include an insecticide in the second burn-down spray too.”
As for which crop to grow, he says forage rape, turnips, chicory, and plantain are the main options for milking cows, possibly laced with clover in the case of the latter two.
“If you want to multi-graze, then you default to the herbs because with cows, the brassicas are pretty much a one-hit crop. You might get repeat grazings of rape with sheep or young stock but it’s hard to manage the residual to get good regrowth after cows have been on it.”
Chicory or plantain are available for grazing earlier than the brassicas, but need grazing in a fairly tight rotation, every 12-15 days once ready, to avoid going to seed with consequent loss of palatability and feed quality.
Turnip and rape, on the other hand, can be used to carry a bulk of feed forward into a summer deficit. C4 grasses such as millet, sorghum or grazing maize can do a similar job but feed quality isn’t as good so they’re maybe not ideal for milking cows, and don’t suit cooler climates either.
Choosing between the brassicas, turnips are generally higher in soluble carbohydrate than forage rape, which is higher in protein. For summer dry climates Nichol says forage rape is a better option than turnips.
To decide when to sow, work out when the feed is most likely needed, look at crop time to maturity, and work backwards, he advises. Frosts should be avoided and soil temperature needs to be 10C and rising for the brassicas and slightly higher again for the herbs.
“It’s really important there’s no risk of frost because it can vernalise plants, especially brassicas, and they would go to seed earlier than expected.”
If crops are to be break-fed then good power in the paddock is important, with easy access to water.
All four crops have small seed so shallow sowing is critical.
“Seed shouldn’t be on the top but all too often it’s put in too deep with these crops: 10-15mm is the maximum.”
A common mistake is to set drills up in gateways or on headlands which are harder than the body of the paddock with the result that seed goes too deep when the machine hits softer ground.
Nichol says seek advice on crop, cultivar, and seed rate decisions.
“For example, forage rape cultivars vary in their time to feeding following sowing so it is important to select the appropriate cultivar. They need to ‘ripen’ as indicated by a reddening of the outer leaf prior to feeding to reduce the risk of photosensitisation.”
KEY POINTS
- Agronomic essentials
- Rectify or avoid paddocks with soil structure or fertility problems.
- Ensure paddock is set up for feeding, including internal fencing and water.
- Sow appropriate crop option at the correct sowing rate.
- Apply fertiliser as per plant requirements.
- Control weeds and pests before crops emerge.
- Sow after last frost – vernalisation risk.
- Don’t drill too deep – 10-15mm maximum.
- Monitor for weeds, pests and nutrient deficiencies post sowing: act promptly if required.
- Chicory, plantain and clovers: best for repeat grazing.
