KindHarvest summary: Clay soils have strong water- and nutrient-holding capacity, but small pore spaces can restrict oxygen, root growth and rainfall infiltration. Agronomist Dale Strickler argues that improving aggregation is the central task in making clay soil easier to manage and more productive.
Why clay can behave poorly
Water and nutrients held in clay are only useful when roots can reach them. Poor aeration can keep roots shallow, while a sealed or compacted surface sends rainfall into runoff. The result can be waterlogging when wet and drought stress when dry.
Three areas for improvement
First, support aggregation by building organic matter, maintaining suitable calcium and pH, encouraging root growth and protecting microbial and mycorrhizal activity. Stable aggregates create larger spaces for air and water between groups of fine particles.
Second, keep the surface covered with living plants or residue. Cover softens raindrop impact, reduces surface sealing, moderates temperature and slows evaporation. Third, protect earthworms and other soil organisms that create larger channels through the profile.
Practical caution
Clay soils vary, and amendments should follow soil testing rather than a generic recipe. Avoid working wet soil and assess drainage, compaction and sodicity separately. Reduced disturbance and continuous roots improve structure over time, while rapid physical fixes can damage aggregation.
Related KindHarvest reading
For a broader framework covering soil chemistry, structure and biology, read the KindHarvest soil-health brief.
Source and credit
This KindHarvest Team practice brief is based on an article by agronomist Dale Strickler, published by Green Cover on 27 June 2022. Read the current Green Cover article.