Here’s What Happens When Fertilizer Gets Wet

Fertilizer is a necessary soil amendment that adds nutrition to the soil and supports plants and crops, making their yields bigger and healthier. There are many different ways in which fertilizer is activated after application. 

There are several good and bad things that happen when fertilizer gets wet. Fertilizer needs to be diluted in water, so it doesn’t burn the plants. Water helps disperse the fertilizer and activate inorganic fertilizers. However, too much wetness can lead to degradation, fertilizer burn, and runoff.

In this article, I’ll explain the pros and cons of fertilizer getting wet in more detail. I will also explain what you can do to prevent or fix the disadvantages of wet fertilizer, so read on!

Pros of Fertilizer Getting Wet

Often, fertilizer needs to get wet to be effective, especially if it’s a regular, inorganic fertilizer. Organic and other slow-release fertilizers tend to be adversely affected by water, but they still need moisture to ensure the dispersal of nutrients through the soil. 

Here are some of the benefits of fertilizer getting wet:

Dilution of Fertilizer

One of the primary benefits of fertilizer getting wet is the dilution of its components. Diluting fertilizers lowers the concentration and results in a liquid that is easy to apply evenly to your plants. 

Most fast-release inorganic fertilizers are water-soluble, which means they can be diluted for ease of use. Dilution offers more control over the amount of fertilizer applied to plants and helps prevent fertilizer burn or stunted growth caused by excessive fertilization.

Fertilizers should always be used at less than or at the recommended dilution level and only in the recommended amounts on the package to ensure that your plants are not overfertilized.

Diluting fertilizers is also a great way of making starting solutions for seedlings and newly repotted plants. These starter fertilizers made by diluting the necessary single nutrient fertilizers in the correct blend help plants receive the nutrients they need at the earliest stages of growth.

The dilute nature of starting solutions delivers the nutrients to fragile seedlings and repotted plants with pruned roots in a way they can process them. Wetting the fertilizer and diluting it ensures that the fertilizer application will not lead to desiccation and subsequent fertilizer burn. 

Fertilizer Dispersal Through the Soil

Fertilizer dispersal refers to how fertilizer travels deeper from the soil’s surface to the roots to ensure that the plant receives the nutrients. 

The availability of water determines the effectiveness of fertilizer uptake. Without water, the fertilizer will simply sit on the soil’s surface, especially if it is a solid, inorganic fertilizer. If the fertilizer concentration is high, it could adversely affect soil quality and the plant parts that are in contact with it. 

Most inorganic fertilizers are also water-soluble because they rely on the moisture in the soil to dilute them further and disperse them among the roots of the plants. Moisture moves through the soil, carrying nutrients from the fertilizer to the deepest roots of the plants. 

Activation of Fertilizer Leading to Nutrient Release

We know plants need water to support their nutrient uptake. If they have insufficient water, they will suffer from fertilizer burn when trying to absorb nutrients from the applied fertilizers. 

However, water is also important for nutrient release from fertilizers. For most inorganic fast-release fertilizers, getting wet is necessary so they can start breaking down. This breakdown releases nutrients into the soil, which the plants can absorb. 

Slow-release and controlled-release fertilizers are specially coated to protect them from the influence of moisture. Their water-solubility is limited, which ensures that the nutrients like nitrogen and potassium are released slowly into the soil.

However, if you want the nutrients to be immediately available for your plants like you might for young seedlings or repotted plants, you need to ensure that the fertilizer gets wet.

How Much Rain Does It Take To Activate Fertilizer?

Rainfall is an important source of water for a lot of farms and gardens. What is important to note is that the availability of rainfall is necessary to ensure the effectiveness of fertilizers. 

About 0.5 inches (1.27 cm) of rain is all it takes to activate fertilizer and disperse it. Light rainfall soaks the ground without forming puddles. Light rainfall and irrigation break down the fertilizer applied to the soil, release nutrients, and disperse them to the deepest roots. 

When there is no rain or irrigation, the applied fertilizer loses nutrients like nitrogen to the air in a process called ammonia volatilization

Cons of Fertilizer Getting Wet

Moisture is necessary to dilute fertilizer, disperse it to the roots, and activate it to ensure nutrient release. But nothing is good in excess, and that is true for moisture as well. If your fertilizer gets too wet, a number of adverse effects can occur.

Here are the cons of fertilizer getting wet:

Degradation of the Fertilizer and Nutrient Leaching

As mentioned earlier, gardeners need fertilizer to get wet to break it down and release the nutrients. While this can be a good thing after you’ve applied your fertilizer to the soil, it is not good if your fertilizer has gotten soaked in an unexpected shower. 

If rainwater soaks through your fertilizer, it will result in nutrient loss as the water starts breaking the fertilizer down and carrying the nutrients away. Another problem in this situation is when the rainwater carries the nutrients to nearby lawns, risking fertilizer burn on plants it gets in contact with or fertilizer runoff.

Most fertilizers can’t really go bad, but their effectiveness will be impacted by excess water. When it comes to fertilizers that introduce microbes to the soil like compost, water is extremely dangerous as the waterlogging could kill the microbes resulting in a smelly, anaerobic mess. 

Even after you’ve applied your fertilizer, too much rainfall can be as bad as no irrigation at all. About 0.5 inches (1.27 cm) of rain will irrigate your garden and carry the nutrients deeper into the roots. However, excess rainfall will simply leach all the nutrients out of the fertilizer and carry it off with the flow of water. 

Is It Better To Fertilize Before or After the Rain?

Seeing as water is necessary but can be harmful in excess, it is important to time fertilizer application in a way that the rainfall supports the fertilization process.

It is better to fertilize after the rain. If the rain is heavy, wait a few days to ensure that most of the waterlogging has receded and your fertilizer won’t be washed away as runoff. After the rain, the ground will be moist enough to activate fertilizer and disperse it to the roots. 

Fertilizing before rainfall can also lead to volatilization or loss of nutrients if the rains are delayed. The fertilizer might end up sitting on the surface of the soil for too long and degrade in the air. 

Excess Water Leading to Fertilizer Runoff 

Excess rainfall or irrigation leaches the nutrients and can even wash off the fertilizer entirely. The soil structure can’t hold on to the water, which runs off, and takes the applied fertilizers along with it. 

This runoff then enters groundwater reservoirs or freshwater supplies, polluting the water with the fertilizers and the excess nutrients. This is especially dangerous when it comes to inorganic fertilizers, as they can cause oxygen depletion, algae blooms, and ammonia toxicity in water bodies, among other concerns

Managing the irrigation and timing of fertilizer application around rainfall patterns is crucial to preventing fertilizer runoff. 

Leaf Burn Caused by Foliar Application to Wet Leaves

Foliar application of fertilizer is a good way to provide supplemental nutrients in addition to fertilizers added to the soil. However, correct application is crucial to ensure that there is no leaf burn. 

Some amount of moisture is necessary, especially in the soil, to ensure that the leaves are turgid and can absorb the fertilizer. However, if fertilizer is applied when the leaves are dried on the inside and wet outside, the fertilizer salt will further draw moisture from the leaves. As water is removed from the leaves, they experience desiccation, leaf burn, and eventually, death. 

The only moisture that leaves need to ensure absorption of foliar fertilizers is as much is offered by dew, mist, or fog. 

How Do You Dry Out Wet Fertilizer?

Wet fertilizer doesn’t go bad but will be less effective. Nevertheless, you can still try to save it and apply it to your plants, as long as it isn’t mixed with pesticides of any kind.

To dry out your wet fertilizer, lay out a tarp and spread it out in the sunlight. If the fertilizer has clumped up too much to be spreadable, you can try mixing it with limestone or gardening sand first. Once it’s dry, break it up and sift it till the particles become fine again.

Limestone can affect the pH value of your fertilizer, so be careful when mixing it in. Remember that the fertilizer may have degraded, but you still need to be careful about applying it because you don’t want to over-fertilize your plants. 

Final Thoughts

Fertilizer needs wetting to ensure dilution, activation, and dispersal into the roots, but the amount of water must be controlled. 

If fertilizer gets too wet, it leads to degradation of the fertilizer due to the leaching of nutrients by the water and even leads to leaf burn. The fertilizer can also get washed away due to excess rain or irrigation, flowing into water bodies and polluting them. 

You can read my other article on fertilizing indoor and outdoor plants here: How to Fertilize Indoor & Outdoor Plants (Ultimate Guide)

Alexander Picot

Alexander Picot is the principal creator of TheGrowingLeaf.com, a website dedicated to gardening tips. Inspired by his mother’s love of gardening, Alex has a passion for taking care of plants and turning backyards into feel-good places and loves to share his experience with the rest of the world.

Recent Posts