Water hardness plays a crucial role in the application of fertilizers, especially when they offer their ingredients separately depending on the water hardness. But what exactly is water hardness, how is it determined, and what impact does it have on the substrate? In this blog post, we will address these questions in detail.
Water hardness refers to the amount of dissolved minerals, particularly calcium and magnesium salts, in the water. The higher the concentration of these salts, the harder the water is. Soft water contains only small amounts of calcium and magnesium ions, while hard water contains a high concentration of these minerals. Water hardness affects various aspects of horticulture, such as nutrient availability and the pH value of the soil or substrate.
For Germany, water hardness can be determined on the website Water Hardness Germany and is usually measured in degrees of German hardness (°dH). This value indicates how many milligrams of calcium oxide (CaO) are dissolved per liter of water. Depending on the hardness level, water is divided as follows:
- Soft Water: 0 to 8.4 °dH
- Medium Hard Water: 8.5 to 14 °dH
- Hard Water: 14 to 21 °dH
- Very Hard Water: over 21 °dH
Water hardness has a direct influence on the substrate and nutrient availability. In particular, the ratios of calcium, magnesium, and other trace elements can change, thereby affecting plant growth. The following points are particularly important:
- Nutrient Absorption: Hard water can limit the availability of important nutrients like iron and phosphorus because these elements are more likely to form insoluble compounds.
- pH Value: A high calcium and magnesium content in water can raise the pH value of the substrate, which may be problematic for certain plant species that prefer a lower pH.
- Substrate Structure: Very hard water can also negatively affect the structure of the substrate over time, as minerals can accumulate and cause the substrate to crust over.
Choosing the right fertilizer and adjusting irrigation to the water hardness are crucial for healthy plant growth. Many fertilizer manufacturers now offer specialized products for soft and hard water to meet different needs. By knowing and understanding the water hardness and how it influences the substrate and nutrient absorption, the best possible conditions for the plants can be created.