Turnips for summer milk production

Abstract

Recently many dairy farmers have sown turnips as a summer feed for lactating cows. This paper reports on a national survey of turnip crops in 1994-95, an experiment on turnip yield responses to N fertiliser and two short-term supplementary feeding trials. Farmers had on average 4.3% of their farms in turnips with a mean yield of 7.4 t DM/ha (range 0 to 15.2 t DM/ha) (n = 328). Barkant was the highest yielding cultivar and mixtures yielded significantly less than Barkant alone. Rainfall in November and December but not January was positively associated with turnip yield. Fertiliser N after sowing increased turnip yield by 13.2 kg D/kg N, but fertiliser N at sowing or P fertiliser in the three months to sowing had no effect on yield. In contrast to the survey, application of 25, 50, 100 or 200 kg N/ha after sowing at TARS gave no significant increase in total DM yield. Supplementing pasture with 3.6 and 5 kg turnip DM/cow/day at DRC and TARS gave milksolids responses of 26 and 18% respectively compared to pasture only. The survey highlighted the variability of turnip yield, and although many growers reached the economic break-even point of 8-10 t DM/ha, there are less risky alternatives to summer turnips such as purchased maize silage and pasture from N-boosted spring pasture. Keywords: Barkant turnips, brassica, dairying, farm survey, milksolids, nitrogen