Guideline Index

Chapter 2: Limits to Plant Growth

2.6 Soil Constraints

These can be any physical or chemical restriction to the normal root proliferation into the subsoil. Constraints can be naturally occuring; in the case of a dramatic change in layers or horizons, or as a result of pasture management in the case of pugging. Examples include a build up of chemical residues from herbicides; an increase in subsoil sodicity or salinity; an extreme soil pH – either acid or alkaline; a sudden physical change to soil structure due to compaction issues; nutrient imbalances – whether toxicities or deficiencies; or even just a lack of soil depth relative to the rooting depth of the pasture species.

Some soil constraints can be identified by soil testing, or a physical or visual examination. The constraint can often be minimised with the use of correct nutrition or the addition of soil ameliorants; be they organic (manures) or chemical (lime or gypsum). Managing soil constraints is covered in detail in Chapter 7.