Soil pH and its importance for soil

The key to healthy, fertile land

The quality of soil – our most fundamental resource – directly affects crop yields, plant health and the profitability of farming. Among the many factors that determine its fertility, soil pH is particularly important. Its level affects nutrient availability, microbial activity and soil structure. Soils that are too acidic or too alkaline can hinder healthy plant growth and lead to lower yields. In the context of climate change and rising agricultural production costs, maintaining the right pH is not only a matter of caring for soil quality, but also an investment in the farm’s future.

What is pH and why does it matter for soil?

pH is a measure of how acidic or alkaline soil is. The pH scale ranges from 0 to 14, with 7 being neutral.

If soil pH is below 7, it is acidic, and if it is above 7 – alkaline. For farmers, it is important that the soil has the right pH for the crops being grown, as this affects nutrient availability and the health of the whole soil ecosystem.

Very acidic soils, with a pH below 4.5, struggle to retain important nutrients such as phosphorus, magnesium and calcium. Worse still, under such conditions aluminium and manganese toxicity increases, which harms root development and limits the uptake of water and nutrients by plants. As pH rises to slightly acidic levels (5.5–6.5), plants can take up phosphorus and other micronutrients more easily, and more beneficial micro-organisms develop in the soil, improving its fertility.

Soils with a pH close to neutral (6.6–7.5) are the most favourable for most crops, as they provide optimal conditions for plants and soil organisms. It is under these conditions that micro-organisms break down organic matter most efficiently. However, if the soil is alkaline (pH above 7.5), deficiencies of zinc, copper and iron may occur, which can lead to yellowing leaves and lower yields.

The right soil pH is the foundation of healthy, productive crops, so it is worth checking pH regularly and responding to any changes.

How do you test soil pH?

To manage soil pH effectively, it must be monitored regularly. Ideally, tests should be carried out at least once every two years, and optimally every season before sowing. Various pH testing methods are available, from simple tests to advanced laboratory analyses.

The most basic method is to use soil testers available from agricultural shops. They are easy to use and allow a quick estimate of pH. Another method is indicator strips, which change colour depending on soil pH. This is an inexpensive option, but considerably less accurate. Electronic pH meters give much better results, allowing fast and precise measurement without complicated tests.

The most accurate method of soil pH analysis, however, is laboratory testing. In addition to pH itself, it provides a complete picture of soil composition and structure. This knowledge makes it possible to tailor fertilisation and other agronomic practices more precisely.

How do you change soil pH?

If tests show that the soil pH is unsuitable, corrective action is needed. Depending on requirements, various methods can be used to lower or raise pH.

To raise soil pH – that is, to reduce its acidity – liming is used. The most common products are calcium fertilisers such as chalk, ground limestone (calcium carbonate) or quicklime. Liming improves soil structure, supports the development of micro-organisms and increases the availability of phosphorus and other nutrients. However, it is important to lime in moderation, as too much lime can make soil excessively alkaline, which is also unfavourable for plants.

Lowering pH – that is, acidifying the soil – is less common, but necessary in some cases, especially if the crops grown prefer acidic conditions. Elemental sulphur, sulphate fertilisers and acidic peat are used to acidify soil.

The impact of soil pH on agriculture in an era of climate change

Climate change, increasingly frequent droughts and extreme weather events make managing soil pH even more important. Maintaining the right pH improves the soil’s ability to retain water, which is especially important during periods of low rainfall. Soils with the right pH bind nutrients better, which translates into more efficient fertilisation and reduced financial losses.

Greater profitability of agricultural production is directly linked to soil pH management. At the right pH, plants can absorb macro- and micronutrients more efficiently, which means farmers can reduce the amount of mineral fertilisers they apply and thus cut production costs. In the long term, improving soil quality leads to more stable yields and better crop resilience to adverse weather conditions.

In addition, maintaining the right pH supports soil regeneration and improves soil structure. Soil micro-organisms, which play a key role in breaking down organic matter and cycling nutrients, thrive best in soil with the right pH. This means that the right pH promotes natural biological processes, reduces the need for chemical plant protection products and improves the health of the entire ecosystem.

Maintaining optimal pH is one of the simplest yet most effective steps a farmer can take to ensure the long-term fertility of their land and the profitability of their farm.