Do Turnips Put Nitrogen In The Soil?

Do Turnips Put Nitrogen In The Soil?

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Turnips are a versatile root vegetable that can be enjoyed in many dishes. But did you know that turnips can also play an important role in improving the health of your garden’s soil? Specifically, turnips have the ability to fix nitrogen in the soil. In this article, we’ll explore the science behind turnips’ nitrogen-fixing abilities, as well as other benefits of growing turnips and tips for maximizing their nitrogen-fixing potential.

What is Nitrogen Fixation?

Before we dive into the specifics of turnips’ nitrogen-fixing abilities, let’s first define what nitrogen fixation is. Nitrogen is an essential nutrient for plant growth, but atmospheric nitrogen gas (N2) cannot be used directly by plants. Instead, nitrogen must be converted into a usable form, such as ammonium (NH4+) or nitrate (NO3-). This process is called nitrogen fixation.

Some plants have the ability to fix nitrogen through a symbiotic relationship with nitrogen-fixing bacteria. The bacteria live in nodules on the roots of the plant and convert atmospheric nitrogen gas into ammonium, which the plant can then use for growth.

Do Turnips Put Nitrogen In The Soil?

turnips are capable of fixing nitrogen in the soil but to a limited extent. Turnips are capable of hosting nitrogen-fixing bacteria, but they are not as efficient at fixing nitrogen as other leguminous crops, such as beans or peas. However, every little bit helps, and turnips can contribute to the overall health of the soil.

Studies have shown that turnips grown in nitrogen-depleted soil can increase the soil’s nitrogen content by up to 100 kg of nitrogen per hectare per year. This may not seem like a lot compared to other nitrogen-fixing crops, but it can still make a difference in soil health.

Factors Affecting Turnips’ Nitrogen-Fixing Ability

Several factors can affect turnips’ nitrogen-fixing ability. One important factor is the type of bacteria present in the soil. Some strains of bacteria are more efficient at nitrogen fixation than others, so it’s important to ensure that your soil has a healthy population of nitrogen-fixing bacteria.

Another important factor is the health of the turnip plant itself. Healthy turnips with strong root systems are more likely to host nitrogen-fixing bacteria and contribute to the overall health of the soil.

Maximizing Turnips’ Nitrogen-Fixing Potential

While turnips may not be the most efficient nitrogen-fixing crop, there are still ways to maximize their nitrogen-fixing potential. Here are some tips for growing turnips that will help increase their nitrogen-fixing abilities:

  1. Plant turnips in nitrogen-depleted soil. Turnips are more likely to fix nitrogen in the soil that is lacking in this essential nutrient.
  2. Use inoculants. Inoculants are bacteria that can be added to soil to improve the soil’s nitrogen-fixing abilities. Look for inoculants specifically designed for turnips.
  3. Practice crop rotation. Planting turnips in a field that has previously hosted a nitrogen-fixing crop, such as beans or peas, can help increase the soil’s nitrogen content.
  4. Avoid excessive nitrogen fertilization. If you add too much nitrogen fertilizer to your turnip crop, it can actually inhibit the growth of nitrogen-fixing bacteria.

Other Benefits of Turnips

In addition to their nitrogen-fixing abilities, turnips offer several other benefits for gardeners. For example, turnips are a low-maintenance crop that can tolerate cooler temperatures, making them a great choice for fall and winter gardening. Turnips are also a nutritional powerhouse, containing vitamins C and K, as well as fiber and antioxidants.

Another benefit of turnips is their ability to improve soil health. As turnips grow, their roots break up compacted soil, allowing for better water and nutrient absorption. Additionally, turnips’ leafy greens can be used as a natural mulch, helping to retain soil moisture and prevent weed growth.

Companion Planting with Turnips

Turnips also make great companion plants. Companion planting is the practice of planting certain crops together to maximize their growth and health. Some companion plants that pair well with turnips include:

  1. Beans and peas: These nitrogen-fixing crops can help improve the soil’s nitrogen content and provide support for climbing turnip varieties.
  2. Brassicas: Brassicas, such as broccoli and cauliflower, can help deter pests that may feed on turnips.
  3. Carrots: Carrots and turnips make great neighbors in the garden. Carrots have long taproots that break up the soil, while turnips have fibrous roots that create a more aerated soil environment.


While turnips may not be the most efficient nitrogen-fixing crop, they can still contribute to the overall health of your garden’s soil. By practicing good crop rotation, using inoculants, and avoiding excessive nitrogen fertilization, you can maximize turnips’ nitrogen-fixing potential. In addition to their soil-improving abilities, turnips offer many other benefits for gardeners, including their nutritional value and versatility in the kitchen. So, the next time you’re planning your garden, consider adding turnips to the mix for a healthy and thriving growing season.

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