- What are heavy metals and why are they toxic to us?
- Which fertilizer does the heavy metal get into the garden?
- Which soils are particularly at risk from heavy metals?
- How can I reduce heavy metals in my crop?
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Heavy metals can accumulate in private gardens in particular. We explain here whether this is dangerous & how you don't get a problem with heavy metals.
Many people are aware that food sources such as fish are increasingly contaminated with toxic heavy metals such as mercury. But we can also ingest harmful heavy metals through plant food, since plants absorb these substances through the soil and the roots. In the home garden in particular, incorrect fertilization in connection with unfavorable soil can lead to increased heavy metal levels in your own harvest. But you shouldn't panic right away: There are simple and uncomplicated solutions that prevent the problematic heavy metals from getting into the soil or being absorbed by the plants - find out more here.
What are heavy metals and why are they toxic to us?
When we hear the term heavy metal, we usually think of a toxic metal that should not get into our bodies. However, this prevailing opinion is only half the truth. Because the group of heavy metals also includes vital minerals such as copper, manganese or zinc. These minerals are often referred to as trace elements. As the name suggests, humans only need very small amounts of these substances for everything to function smoothly in our bodies. On the other hand, higher amounts can have negative effects and cause illness.
In addition to the vital heavy metals, there are also heavy metals such as lead, cadmium, chromium and mercury, which really have no place in our bodies. Depending on the heavy metal, even the smallest amounts are sufficient to cause symptoms of poisoning. For example, cadmium poisoning can lead to kidney failure, and excess lead intake can make a person literally stupid. For example, increased lead intake in childhood causes damage to the brain, which translates into a lower IQ andexpress lack of concentration. Heavy metals are also problematic because they accumulate in the body and are only excreted very slowly. A long-term increase in heavy metal intake can therefore only lead to problems such as liver and kidney damage after years.
Which fertilizer does the heavy metal get into the garden?
After reading the above heading, every hobby gardener will probably ask how heavy metals can get into our fertilizer and thus into our food chain. You have to know that mineral fertilizer components such as phosphate are naturally contaminated with heavy metals. In the case of phosphate, it is primarily the heavy metal cadmium. Unfortunately, nowadays there are almost exclusively phosphate deposits with an increased cadmium content, because the cadmium-poor mines are already almost completely exhausted. So if you regularly fertilize with mineral fertilizers that have a high phosphate content, you can enrich the soil with heavy metals in the long term. Interestingly, private gardens, which are often fertilized with a compound fertilizer such as blue grain, are much more heavily contaminated with heavy metals than the discredited field of a commercial farmer. Because a farmer only ever fertilizes as much as the plants really need and absorb - if only for economic reasons.
But the whole truth also includes the fact that heavy metals are not only to be found in mineral fertilizers. Compost can also have high levels of heavy metals. The decisive factor here is the raw materials from which the compost was made. But before you completely lose the desire to garden in your own garden, it should be said: Heavy metals are actually found everywhere and even without fertilization, small amounts of heavy metals can be detected in your garden soil. At this point, a quote from Paracelsus fits very well: “All things are poison, and nothing is without poison; it's the dose alone that makes a thing not poison."
Which soils are particularly at risk from heavy metals?
Just because heavy metals get into the soil doesn't mean they have to be absorbed by the plants. Soils have a so-called buffer capacity. Explained somewhat simply, the buffer capacity ensures that the soil can bind certain substances so that they cannot be absorbed by plants, for example. The amount of buffer capacity depends on thecomposition of the soil. The following components and properties in the soil have a positive effect on the binding of heavy metals:
- High tone content
- Humus is also able to bind heavy metals
- The soil pH should not be below 6
In summary, it can be said that a heavy soil containing humus and clay is able to bind many heavy metals. If the soil is sandy, the heavy metals are more easily absorbed by the plants and washed out into the groundwater. But even heavy soil can only bind heavy metals effectively if the pH value is not too acidic.
How can I reduce heavy metals in my crop?
Reduce heavy metal input through choice of fertilizer
At this point it would be wrong to demonize mineral fertilizers per se. However, there are some problems with mineral fertilizers that do not occur with organic fertilizers. The overall nutrient content of mineral fertilizers is quite high, and the phosphate concentration in particular is often far too high for long-term fertilization. Because most plants only need a little phosphate. In addition, the slowly progressive weathering in the garden soil releases phosphate in a completely natural way. In principle, soil components, which are mostly minerals, are slowly broken down by external influences such as rain. When crushed, other plant nutrients such as iron are released in addition to phosphate. So in our beds there is a natural, albeit light, phosphate fertilization that shouldn't be forgotten.
Unfortunately, the fertilizer declaration often gives a higher value for the application than is actually necessary - just to ensure that fertilizer is bought again quickly. In addition, we usually know far too little about our soil and its composition. So it remains a mystery to us how much fertilizer is really needed at which point. However, we want to garden sustainably and increase soil organisms instead of adding heavy metals to the soil. The organic fertilizers from Plantura are ideal for this. You can trust our quantities and should you mean well: Plantura fertilizers do not increase the entry of heavy metals by 100 percent.
With the tips listed below, you can very practically reduce the amount of heavy metal in your bedsreduce significantly:
- The principle "a lot helps a lot" definitely does not apply to fertilizer
- Biological fertilization is always an advantage due to the natural nutrient ratio
- In the case of an acute nutrient deficiency, fertilizers with only one nutrient can also be purchased (e.g. nitrogen)
- Study the nutrient needs of the plants you grow, then only feed what the plant needs
Reducing heavy metal pollution from tillage
To ensure that heavy metals remain stored in the soil and do not get into our plants and thus into our food, we have two tips for you: The most important measure is to control the pH value. Because even a heavy soil with a lot of clay and humus cannot absorb large amounts of heavy metals if the pH value is acidic or even very acidic. If the soil turns out to be too acidic, it should be limed. This increases the pH value again. In addition, the soil can be enriched with humus in the long term. By incorporating humus, more heavy metals are bound and, by the way, you are also doing something good for your plants.
In summary, it can be said that the heavy metal problem will probably become more important in the coming decades. Even if the pollution in Germany is very low compared to that in developing countries, for example, a rethinking of fertilization is relevant. After all, who would want the soil in their own garden, which has been cultivated with so much love and effort, to be contaminated with heavy metals?