Soil acidification is increasing worldwide, which has serious consequences for agriculture and the fight against hunger. This is also a significant problem in Germany, as the first nationwide soil condition survey in 2018 showed: only around a third of the arable land analysed had an ideal pH value, while the majority of soils were over-acidified.

Acidity problems in agriculture

The pH value has a direct influence on the growth potential of crops. It determines the condition of the soil and influences the availability of nutrients for the plants. Most crops develop optimally at a neutral to slightly acidic pH value between 6.2 and 6.8, where nutrients are soluble, soil organisms are active and the soil structure is ideal. Soil that is too acidic, on the other hand, loses its looseness, retains less water and is poorly aerated. As a result, plants absorb fewer nutrients and the activity of microorganisms decreases. As a result, important biological processes are severely restricted or do not take place.

Causes of soil acidification

Natural decomposition processes, the use of lime-depleting fertilisers and acid rain contribute to soil acidification. However, adding lime can partially neutralise these effects. Lime significantly improves the soil environment: it dissolves nutrients, forms bonds between the clay particles in the soil and thus promotes a stable structure. It also optimises the supply of air, water and heat to the soil, increases the activity of soil organisms and thus supports various biological processes such as humus formation and mineralisation.

Optimising yield efficiency through pH regulation with humic acids

Humic acids have similar soil-improving properties to lime, as they balance the pH value of acidic soils and increase their buffering capacity. This means that acid rain has less damaging effects on the soil. Furthermore, humic acids promote root growth and stimulate microbial activity in the soil, which in turn increases the nitrification rate. In acidic soils, where aluminium and heavy metals are present in dissolved form, humic acids act by binding and immobilising these elements. They support the formation of stable clay-humus complexes and thus reduce soil erosion. As an alternative to lime, humic acids offer advantages especially in highly acidic soils and are characterised by their long-lasting effect, which improves the soil-plant system for up to five years.

Versatile pH regulation through humic acids

Humic acids play an important role not only in acidic but also in alkaline soils. They act as natural chelating agents for metal ions, which facilitates nutrient uptake by plant roots. Humic acids also dissolve phosphate-bound calcium and other nutrients and trace elements, forming complexes with them and making them available in a form that can be utilised by the plants. 

Deepen your knowledge of the use and effectiveness of humic acids in agriculture and horticulture.