Nutrients for Growing Turnips

Soil

• Turnips generally prefer loose loam soil with good drainage, although they do well in many different types of soils. The ideal pH for turnip growth is in the 6 to 6.5 range. Soil pH is important because it affects turnip growth in many ways; excessively acidic or alkaline pH can make certain nutrients unavailable to the turnip and cause other problems. If the pH is just slightly outside of the optimum range, however, don't try to overcorrect -- you could easily overshoot the desired value and cause a more serious problem.

Nutrients

• Turnips are similar to many other leafy greens in terms of their fertilizer needs. Nitrogen fertilizer can improve both yield and the protein content of the vegetable, although it's important not to overdo it, because excess nitrogen can actually reduce root growth. If you're using turnips as a forage crop, be especially careful since the leaves can quickly take up nitrate from the soil, so the leaves may exhibit relatively high levels for a few weeks after application. High-nitrate concentrations can potentially be toxic to grazing cattle.

Fertilizer

• Another important nutrient is phosphorus, which is essential for healthy turnip root growth. Most fertilizers contain the three most important nutrients -- nitrogen, phosphorus and potassium -- in variable ratios. The percent composition for nitrogen, phosphorus and potassium, or N-P-K, is generally listed on the front of the bag in the form of three numbers separated by hyphens. Common garden fertilizer blends like 10-20-10 or 5-10-10 work well. If you use 10-20-10, scatter 2 or 3 lbs. across every 100 square feet after tilling and before planting. For 5-10-10, by contrast, 3 lbs. per 100 square feet is usually a good amount.

Considerations

• Since excess nitrogen can have undesirable effects on your turnips, have your soil tested before applying additional fertilizer, especially if you suspect your turnips are suffering from a deficiency of one kind or another. If your phosphorus levels are sufficient but nitrogen is low, you can use calcium nitrate instead of a combination fertilizer. Some people also prefer to use compost or well-rotted manure instead; both work well as a source of nutrients. If you use lawn fertilizer for turnips, make sure the brand you buy does not contain herbicides, because these will kill your turnips swiftly.