Until recently, the term ‘soil health’ has not been widely used. However, it has gained traction in the last few years by farmers, growers and the wider stakeholder community. No single set of on-farm management practices can put soils in good health. Good soil husbandry requires a flexible approach that is likely to vary from field to field, and season to season. The agricultural industry has a huge breadth of experience and depth of understanding of the practical issues involved in the management of soils within UK crop rotations. Recent research, including that funded by AHDB and the BBRO, has also advanced knowledge of sustainable soil management. This publication brings together such information. It looks at what makes soil and how it is classified. It outlines soil-related issues and how they can be addressed.
What is healthy soil?
The intricate web of relationships between physical, chemical and biological soil components underpins crop and livestock health and productivity. Protecting soil health is also critical to environmental sustainability, as soils: • Exchange gases, such as carbon dioxide and nitrogen oxides, with the atmosphere • Regulate the flow of water and rainfall in the water cycle • Provide nutrients for plant growth, by breaking down organic matter and altering chemical fertilisers • Transform and store organic materials, as part of the terrestrial carbon cycle • Degrade contaminants applied through human activities or left by floods and aerial deposition A healthy soil is able to sustain, in the long term, these important functions. In a healthy soil, the interactions between chemistry (pH, nutrients and contaminants), physics (soil structure and water balance) and biology (including earthworms, microbes and plant roots) are optimised for the conditions in that place.
Soils form over thousands of years through local interactions of climate, geology, hydrology and management. Physical and chemical alteration (weathering) break down parent materials (solid rocks and drift deposits). Finally, biological cycles of growth and decay produce the critical extra ingredient: organic matter (OM). Each field has unique soils. Underlying geology determines the soil parent material and its properties, including soil depth, stoniness, mineralogy and texture. Soil maps, therefore, often closely resemble geological maps. Parent material is the main determinant of whether soils are likely to have a shortage or an abundance of particular nutrients – phosphorus (P), potassium (K) and magnesium (Mg) or trace elements. For example, some clays release enough potassium to support moderate crop growth, without additional fertilisation. Potassium-releasing clays include: chalky boulder clay, Gault Clay, Kimmeridge Clay, Weald Clay, Oxford Clay, Blisworth Clay. Note: Carboniferous clays do not release much potassium.
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