Assessment of disturbing layers
A compacted layer often has a negative effect on yield. A disturbing layer limits rooting and leads to water stagnation. In ruts or on headlands, you can quickly see what compaction can look like. A plough sole or disturbing sand layer in the plot is often less noticeable. A disturbing layer or resistance can be felt by cutting down with a blade along the side of the profile pit. Even when assessing a clod, disturbance quickly becomes apparent due to the presence of sharp-blocky structural elements. To take the right measure, it is important to know how thick the disturbing layer is and how deep it is.
Image 1: no disturbing layers, good structure.
Image 2: moderately disturbing layer, palpable resistance, but some roots still penetrate.
Image 3: severely disturbing layer, compact (no pores or worm passages), palpable resistance, rooting stagnating.
Instead of sharp-blocky elements, a disturbing layer can also be a peat, sand, loam or shell layer.
Disturbing layers can be addressed by tillage operations such as (deep) turning or (deep) spading. Before deep tillage, map the soil thoroughly and, if in doubt, always involve a soil expert. After deep tillage, it is essential that the soil regains its structure. Therefore, immediately after deep tillage, you should grow a deep-rooting crop such as cereals, reed fescue or alfalfa. The root passages create a new pore structure in the subsoil.