An international soil health specialist has said that it is possible for farmers to improve soil health.
Prof. Mike McLaughlin, from Co. Antrim, is a research scientist with the University of Adelaide in Australia.
Speaking on the Tillage Edge podcast in relation to improving soil health, McLaughlin said: “It depends on the starting point. Obviously, the addition of nutrients will change the potential for crop production, where a specific soil is concerned.
“The addition of lime to an acidic soil will change its ability to produce crops. Nutrient availability and root growth are limited because of soil acidity.
“In countries like Australia, sodic soils create major challenges for farmers – primarily because they have a very poor structure.
“In these soils, we add gypsum in order to improve their physical quality. Soils that are very deficient in organic matter have both a very poor soil structure, but they are also very low in nutrients,” he said.
Improving soil health with organic matter
According to Prof. McLaughlin, adding organic matter to these soils will improve both structure and fertility.
“This approach will also help develop the aggregate composition of soils, which improves both aeration and water retention capacity,” he explained.
“Organic matter also has the ability to hold nutrients against the pressure of leaching.”
In China, human excreta has been added to soil for thousands of years while, in Europe, the addition of organic waste to soils has been the norm for centuries. These practices have been undertaken in order to boost crop outputs.
“All of this has changed dramatically over the last century, due to the development of artificial fertilisers,” Prof. McLaughlin continued.
“There are still fundamentals that must be addressed when it comes to improving soil structure that only the likes of organic matter can change.
“In some parts of England, for example, large quantities of clay were added to soil as a means of improving crop outputs.
“This is a process called marling. Clay is the most reactive component within a soil.”
“The specialist explained that it is difficult to change the overall clay content of a soil. It is a case of adding tonnes per hectare.
Where organic matter is concerned, large quantities would need to be added to soils if significant structural change is to be effected.
“Organic matter impacts soil quality at a physical, chemical and biological level. Aggregate stability is a key determinant of soil health,” McLaughlin said.
“However, this factor is significantly controlled by the organic matter content of a soil.”