In recent years, consistent yields of 20-30t DM/ha were achieved in most areas, with best practice agronomy, in some areas, well above this.
Bulb growth generally occurs in late summer to autumn when the full leaf canopy can use warm, sunny conditions.
The crop grows and stays at a consistent feed quality for approximately 400 days.
Like all crops, FB yields are dependent on available water, but there are several features of the crop that provide excellent water use efficiency.
In most circumstances yields have been maintained at approximately two-thirds of the typical expected yield, even in extended summer dry intervals.
The original beet was a Mediterranean seashore plant, with a long (c.3m) taproot to draw moisture up, providing reasonable tolerance to drier soils and summer dry once established.
FB crops often 'hold on' better than winter crop alternatives such as brassicas, proved by the past few dry years on the Mainland, and when other feed stocks are depleted, FB can be used in summer and autumn.
While dependent on the sowing date and growing environment, yields of 15-30t DM/ha in late summer 2015 were measured across New Zealand, and available DM is clearly a valuable 'green feed' source when other feed is unavailable. FB has been used for this for some years here.
While FB is suitable feed for all cattle and sheep in summer and autumn, there are several considerations to effective use.
First, grazing the crop early will obviously 'cost' some potential yield.
There is limited data on peak growth rates, but 150-250kg DM/d summer growth was measured on the Mainland, and back calculations of measured crops in the North Island give similar values.
Note grazing the leaf with lambs also reduces potential yield by removing canopy to use the sun, requiring bulb stores to regrow leaf tissue first.
FB is high-energy feed and has an absolute requirement for a transition period to adapt stock. The process takes 14 days, and detailed information is widely available and should be carefully enacted.
Effective use of FB requires a fibre supplement. The crop does not provide sufficient fibre for normal rumen function, so grass, hay or straw is required.
The benefits to drought-affected farms are the provision of a hardy feed when other feed is scarce, the low cost and high energy supply of the crop, and the high yields that allow high stocking rates on crop, which pulls stock off scarce pastures in autumn to bank feed.
The flexibility of FB in holding good feed for use in summer, autumn, winter and the following spring give it a place in drought mitigation in most areas of New Zealand.
