Brassicas are better for one-hit quantity and quality in bulk. Even with a low payout forecast there’s still a place for summer crops if a summer feed deficit is likely, DairyNZ financial modelling shows.
However, they’re not for everyone and even in the forecast El Nino-induced dry summer it’s a close call between crop, silage or palm kernel to fill a summer deficit, says the levy body’s farm systems specialist Chris Glassey.
“Even at $3.85/kg milksolids (MS) it is still better to do something to reduce a summer feed deficit than nothing. Ensiling a true spring (pasture) surplus to feed later comes out top in terms of feed, then nitrogen applied to generate a surplus.
“Crops, then palm kernel (assuming $220/tonne landed on farm) rank next, but it’s by no means cut and dried and individual circumstances could change that ranking.”
DairyNZ plans to put the modelled information on its website so farmers can input their own figures to see which works out best under different scenarios. If relying on palm kernel, contracting a proportion as a precaution against shortage and price hikes is advisable.
An advantage of silage or crop is they remove or reduce a spring surplus and shift feed supply to later in the season when deficit is more likely. Silage is more flexible, in that it can be used at any time, but crops typically have a fairly tight use-by window, Glassey points out.
“This is a weakness with the crop approach. Often you can’t predict when the deficit will occur or when it’s at its strongest, so there’s a potential mismatch with when your crop’s ready and when the feed’s needed.
“The choice of crop can help with that. A one-off grazing crop like turnip has a fairly narrow window when it should be grazed and if that doesn’t coincide with your deficit then you’ve got a problem, but with a crop like chicory or forage rape there’s more opportunity to graze it over a range of dates. The problem with those though is you don’t have the same volume of feed available at any one time and you are reliant on regrowth to give you the same amount of feed overall.”
A crop can be part of a pasture improvement process, and might be used to redistribute nutrients from an area of high fertility, such as the effluent block, to outlying, less fertile pasture.
“Location of the crop on the farm in relation to the farm dairy needs to be carefully considered too. If it’s too far away there can be too much walking for the herd out to the crop, then back to grass, and in for milking.”
Whatever the crop grown, achieving a good yield is paramount for profitability.
“From sowing to regrassing, there’s probably not a lot of difference in total yield between the best chicory, turnip and forage brassica crops. They can all do about 16t DM/ha, but the average achieved on farm is more like 11-12t DM/ha. At that they’re more marginal.”
Chicory can be made to last a second or third season but needs careful management in autumn and winter to ensure good second-year yield. If feed is short in autumn, it can be tempting to put the cows on a lush crop of chicory, with potential damage to yield in the second year. So more often than not farmers choose a one-season crop, Glassey says.
Plantain should be considered a two- or three-year crop, so isn’t really in the same category.
KEY POINTS
Summer crop considerations
Climate: suit summer dry areas of Northland, Waikato and Bay of Plenty best.
Use to meet summer feed deficit.
Helps reduce spring surplus by taking pasture out for crop.
Decide on one-off high yield, eg turnip, or moderate repeat grazings, eg rape or chicory.
Paddock location relative to dairy and effluent areas.
