It is essential to maintain healthy soil to ensure vigorous plant growth and crop yields. Yet, over time, soil naturally is depleted of nutrients.
The soil will lose nutrients due to crop removal and regular farming practices. Nutrients are also lost to leaching, oxidation, soil erosion, and pH imbalances in the soil. In addition, many contemporary farming practices and chemicals are to blame for many soil deficiencies.
However well you maintain your garden or fields, if your soil lacks essential nutrients, your plants will not thrive. Keep reading to learn the common and unavoidable ways soil loses its nutrients and what you can do to maintain the healthy soil needed for optimal plant growth.
6 Common Ways Soil Loses Its Nutrients
1. Annual Planting and Harvesting Depletes Soil of Nutrients
When people use soil for farming, they often leave the soil depleted of nutrients after the harvest season because the crops use the nutrients in the soil to grow and develop. This nutrient loss is relatively quick compared to soil recovery rates, and annual cropping can do serious damage rather quickly.
Even traditional farming techniques such as tilling can compromise soil structure. For instance, breaking up the soil can destroy essential fungi and bacteria, which risk washing away with the next rainfall.
2. Soil Drainage Leaches Nutrients
Water draining through the soil can also cause nutrient loss. Critical nutrients often get pulled from the topsoil, such as:
These primary nutrients leach away from the roots of plants, resulting in soil deficiency and accumulation of elements in the soil, such as hydrogen and aluminum. This accumulation will turn the soil acidic if left unaddressed.
3. Oxidation Reduces Nutrients
Some elements in the soil are subject to oxidation, turning them into gasses that emit from the soil, lowering nutrient content. Nitrates also are lost this way, as these radicals are affected by denitrifying bacteria.
Unfortunately, these are natural, often unavoidable occurrences that you may not be able to prevent and, in some cases, won’t want to. The best you can do is correct the imbalances when you notice them.
4. Heavy Rains and Winds Erode Soil and Reduce Nutrients
Another natural, unavoidable occurrence that causes soil to lose its nutrients is the weather. Specifically, heavy winds can erode topsoils, blowing nutrients away and resulting in an imbalance. Similarly, heavy rain can flood soil and carry nutrients away from the plants.
5. pH Imbalances Result in Inaccessible Nutrients
Soil that is too alkaline or too acidic impacts the nutrients available to your plants. Markedly, if your soil has too much of a particular nutrient, this can prevent other essential nutrients from being absorbed by the roots.
In some cases, the soil doesn’t lose its nutrients—they’re still there. Yet, as far as your plants are concerned, they’re gone.
For example, high phosphorus and nitrogen concentrations prevent plants from getting the potassium they need for proper growth. If you’re lucky, it will only stunt growth and lower yields. Unfortunately, this is likely to kill your plants.
Acidic soil with a low pH breaks down and leaches aluminum, calcium, and iron. It also causes any living organisms in the soil to slow their activity, which leads to decomposition.
Alkaline soil with a high pH has an excess of magnesium and calcium, leading to root development and plant growth problems.
Should pH levels reach 8.0 or above, these levels block essential nutrients from reaching plants’ roots. Namely, magnesium and iron fail to get absorbed by the roots, which causes many plants to develop diseases.
To learn more about why soil ph is so important, check out my other article: 5 Reasons Why Soil PH is So Important
6. Harmful Contemporary Farming Practices
Unlike conventional farming techniques, many modern farming practices employ chemicals and heavy machinery in the fields because they allow farmers to produce much higher yields and faster rates. However, the production of such heavy farming is often at the expense of soil health.
Unfortunately, most fertilizers, pesticides, and other chemicals are incredibly harmful to the soil and the environment.
The Role of Arbuscular Mycorrhiza in Reducing Soil Nutrient Loss
Mycorrhizae are essential for providing nutrients to plants. These fungi-root associations are known to help transfer hard-to-absorb nutrients, such as phosphorus, to the plant’s roots to support proper plant growth.
However, a recent publication from the Trends in Plant Science journal discusses the largely overlooked role that arbuscular mycorrhizae may play in reducing soil nutrient loss.
According to the study, they not only help to reduce nutrient loss in soils but may also enhance the entire ecosystem’s efficiency in nutrient use. Indeed, this is encouraging news, as arbuscular mycorrhizae could be the key to increasing global food production sustainably.
This enhanced sustainability is also a significant conclusion for home gardeners and family farmers, as the implication highlights mother nature as the best remedy to nutrient deficiencies.
Markedly, this means that you may wish to think twice about how and how often you feed or condition your soil, as you might be creating different problems while trying to correct others. Instead, letting nature gradually do the work for you may be more advantageous.
Nutrients Commonly Lost in Soil
Your soil may suffer from the loss of various nutrients, but the most common nutrients missing in depleted soil are:
- Calcium – Significant to plant development and structure
- Carbon – Critical to the survival of microbial life
- Manganese – Necessary for photosynthesis and other plant functions
- Nitrogen – Essential macronutrient needed for proper growth
Some Soils Are Naturally Deficient in Certain Nutrients
Some soils are just naturally acidic, while others are more alkaline. For instance, soils made from limestone contain calcium carbonate, which helps to neutralize acid, and are usually less acidic than those of sandstone or granite.
Acidic soil is typical in places with heavy rainfall, as all the alkaline elements, such as magnesium, calcium, and sodium, seep out of the soil with the water, raising soil acidity.
Replacing Nutrients in Your Soil
Numerous amendments are available to help correct soil imbalances. Some work to raise pH, others lower pH. Typically, adding specific organic material or compost can replace what was lost.
For instance, many people know that lime is effective for lowering pH and sweetening soil—and it has little competition in that area. Other people also consider Gypsum and phosphogypsum to contain calcium elements, yet experiments show that they aren’t very effective on their own in altering pH levels.
Conclusively, lime and lime mixed with gypsum or phosphogypsum were the most effective soil amendments for lowering aluminum, the primary cause of acidic soil.
It can also benefit larger areas used for farming to grow cover crops between seasons to help restore nutrients. You should also consider rotating crops to help prevent further nutrient loss.
Can You Sweeten Soil Without Lime?
You can sweeten soil without using lime. The most popular alternative is wood ash, a natural lime substitute that provides calcium to neutralize acidic soil and potassium to support vigorous plant growth. You can also opt for compost or bone meal to maintain sweet pH levels.
If you’re interested in learning more about alternative liming options, check out my other post: How To Sweeten Soil Without Lime (6 Tips)
What Are the Benefits of Using Soil Conditioners?
The benefits of using soil conditioners are increased nutrition, aeration, and water retention in soil. Yet, benefits are only measurable and sustainable in containerized plants. Native soil receives immediate and short-term benefits from conditioners, yet over time, plant health declines.
Several soil conditioning services are available from a myriad of companies, as these treatments have grown popular over the decades. However, just because they’re trendy doesn’t mean that they’re the best course of action. Depending on the soil type, the plant life, or the landscape, some soil conditioning treatments can have negative consequences later on.
Before you make any decisions, check out my post about the efficacy of soil conditioners: Is Soil Conditioner Worth It? How To Decide
While nutrient depletion is unavoidable, you can easily supplement your soil with what it needs using composts and other soil amendments. Test your soil regularly to ensure it has all the nutrients your plants need to stay happy and healthy.