Forage Turnips (Brassica rapa) Common names: A brassica root crop commonly used as a fast-maturing single-graze crop to bridge a feed gap and maintain milk production. The higher-yielding, faster maturing soft, white fleshed turnip varieties are more commonly sown in dairy systems. This type of bulb turnip offers a high- quality feed to supplement pasture and maintain milk production. Testing shows high energy with ME of up to 12-13MJ/kg DM and leaves are a valuable source of proteins. Turnips need a minimum of 60-70 days and have no ripening requirements. The proportion of leaf to bulb varies with individual variety. Land Preparation and Planting • Turnip seeds are very small, and need a fine compact, clod-free seedbed to germinate and establish well. Cultivate paddocks well to a fine tilth. Where soil type and moisture is appropriate, it is recommended to roll the paddock twice before sowing, and once more after sowing, to ensure the seeds have good soil contact. • Critical for a good yield is sowing early while there is good moisture available. Plant the Management crop well before conditions get dry. • Turnips are sensitive to moisture stress • Soil tests should be carried out on paddocks especially at establishment. where turnips will be sown and if required, • Should be sown 70 days before they are fertilizer and lime should be applied the needed to get maximum feed quality. season prior to sowing. . • Crops grown in high fertility will have less • The seed can be sown by broadcasting or weed and pest problems. drilling. Drilling equipment will distribute the • The following are the recommended fertilizer seed more evenly, but still requires rolling rates 70-80kg/ha of phosphate, 60-70kg/ha after sowing. of potassium, and 30-40kg/ha of nitrogen. • With broadcasting, it is generally suggested • Three to four weeks after emergence, apply to sow twice the sowing rate. Typical 75kg N/ha; this ideally done before bulb sowing rates are 0.5 to 1.0kg/ha if drilled, formation. and 2-3 kg/ha if broadcasted. Use treated • Perennial weeds cannot be controlled once seed protect against springtails and the turnip crop is sown, as there are no damping-off diseases. herbicides that can do this economically. Harvesting Pests and Diseases • Turnips cultivars are classified based on a • The main disease threats are club root and “typical days to grazing” basis, with most dry rot. cultivars needing around 60-100 days to • Main insect pests are springtails, leaf mature. In cooler conditions growth and miner, diamondback moth, white butterfly, maturity is slower. aphids, and when direct-drilling, slugs. • Early maturing types take between 60-90 • Inspect young crops regularly by walking days to mature and are those most well into the paddock and, if necessary, commonly grown to boost milk solid apply the appropriate insecticide. production. Medium maturity types take Potential animal health problems between 80-100 days, and late maturing types can take up between 90-100 days to • Most animal health issues occur in the first reach grazing maturity. day or two of feeding, as animals adjust to • Late maturing cultivars have better frost the crop. tolerance and winter keeping properties • Ideally, cows should be fed alternative than the early maturing types. feeds (e.g. pasture or silage) before • Turnip crops can yield over 15 t DM/ha. accessing the crop to minimize the risks. Given summer turnips are usually grown in • Milking cows can lose condition when summer dry areas, a more typical yield to eating turnips if pasture is short. work on is 11.5t DM/ha. • The extra protein in the turnips can lift milk • In dry seasons turnip crops may only yield production at the expense of cow condition; 7-8 t DM/ha. this can be corrected by feeding grass or Conservation and Feeding maize silage at 2-3kg DM silage/day. • Bloating has been reported in cows grazing • Like all supplementary feeds, introduce cows turnip crops. Drenching, or grazing cows on gradually to your turnip crop. turnips after they have eaten some grass • It is recommended you offer a maximum of are ways to overcome this. 2kg DM/cow in the first five days, and • Rumen acidosis can occur if turnips are increase feeding level gradually over the next introduced too rapidly. five days, up to 5kg DM/cow/day. • Introduce them slowly over 5-7 days to • Turnips should make up no more than 1/3 of allow rumen microbe populations to adjust. cow diet to minimize potential milk taint. • In some years, on some farms, • Make breaks long and narrow, to minimize photosensitivity can be seen in stock due to wastage by cows treading on the turnips. the glucosinolates in turnips. Remove • For grazing, begin grazing early maturing affected animals from the crop and give varieties around 70 days from sowing. Later shade, good quality feed and water. maturing varieties, such as, should be ready to graze from 100 days. Acknowledgements “This factsheet was developed with funding from Dutch government (NOW) through the project “Feed and Forage Seed Business Models to support further professionalisation of the dairy sector in Kenya and Uganda”, registered under W 08.240.106, coordinated by KIT Royal Tropical institute and implemented by the Alliance of Bioversity International and CIAT, ILRI and NaLIRRI.”