We are all familiar with the need for regular soil testing which normally only includes the major nutrients, ignoring the importance of soil texture and organic matter. The introduction of a Soil Quality Index seeks to readdress this issue. Looking as it does at the relationship between soil organic matter (soil carbon) and the clay content of the soil.
Researchers at Rothamsted have devised an index which combines soil carbon (taken to be 58% of soil organic matter) and the soils clay content to give an index where anything above 1 is deemed as very good, anything below 0 as degraded with figures in between being deemed moderate or good. The researchers used 3,800 soil samples to devise the index and determined that 38% of English arable soils and 7% of grassland soils were degraded. Look at fields 2 and 4 below both with the same level of organic matter but the one with a higher clay content is moderate compared to the medium loam which is deemed as good. Likewise look at field 1 and 3 which have similar clay content but differing levels of organic matter rating one as moderate and the other as degraded.
The major benefit of this system is that it is a relatively simple soil texture analysis that only needs doing once. It is relatively cheap and then one only needs to monitor organic matters. By using an index it is possible to directly compare fields and allows comparisons between farms and monitoring changes.
If you would like to discuss monitoring your soils, please contact William at email@example.com or your local FCG Office.