Does adding sand improve soil drainage?
Written by
Paul Reynolds
Reviewed by
Prof. Samuel Fitzgerald, Ph.D.In heavy clay soils, the addition of coarse sand provides excellent drainage by breaking up the particles. On sandy soils, the sand causes a concrete-like packing and is detrimental. I have improved clay beds by adding sand, but I have also seen sandy gardens fail due to improper sand application. The main thing is to match the type of sand and the amount to the constitution of your soil.
Clay Soil Solutions
- Use coarse builder's sand with particles larger than 0.5mm
- Mix at 40-50% sand to 50-60% soil volume
- Combine with 20% compost for nutrient balance
- Work amendments 12 inches deep with garden fork
Sandy Soil Alternatives
- Avoid sand - worsens drainage further
- Add coconut coir at 30% volume for moisture retention
- Incorporate compost to build soil structure
- Use cover crops to add organic matter naturally
Application Techniques
- Test soil texture before adding amendments
- Blend sand thoroughly to prevent layering
- Moisten soil before mixing to reduce dust
- Retest drainage after 48 hours with trench method
Coarse sands fracturing the clay and creating drainage holes while fine sands fill gaps. Always use the sand marked 'coarse or builder's grade' with grains visible. Avoid play sand, as it contains fine particulate matter that cements soil together. I specify #2 grade sand for clients, which has the correct particle size of 1-2 mm.
Apply the 1:1 ratio rule with organic matter. To each shovel of sand, apply the same amount of compost. This preserves fertility and improves structure. Apply compost wherever sand is used, because otherwise sand-treated land loses its richness of nutrient. I measure amendments in barrows so as to do easily and accurately on large beds.
Track results by plant response and by drainage tests. Good results will be evident in healthy root development, accompanied by proper sand application, within three to four weeks. Noted decrease in water diameter indicates areas of soil having good drainage. The former seasonal variations must be acknowledged to control future amendments. The methods used in this case will yield lasting results, ensuring a life without inaccuracy.
Read the full article: 10 Essential Raised Bed Drainage Fixes
