Benefits of clay in the soil

Clay, because of its density, retains moisture well. It also tends to be more nutrient-rich than other soil types. The reason for this is that the particles that make up clay soil are negatively charged, which means they attract and hold positively charged particles, such as calcium, potassium, and magnesium.

Perth soils are often depleted of any clay and only consist of sand, therefore adding 1-5% of clay to soil mixes mix has numerous benefits:

• Proven that water content of clay amended soils were double that of unamended soils in low irrigation areas;
• Added clay increases soil moisture retention rates;
• The clay can disperse with wetting and reacts with other soil components;
• The clay has high cation exchange capacity which helps the positive and negative ions in the soil to work together;
• You only need a small percentage 1-5% to make a huge difference to the soil profile.

With water allocation rates and costs of water used on council parks, gardens, lawns, golf courses and so on, this is becoming quite an issue for all the parks managers and superintendents of sporting grounds.

Richgro adds Bentonite clay to mixes which is a high-grade calcium bentonite clay mined from an area 250kms north of Perth. Mixing in or adding small percentages of clay to the Richgro range of landscape and turf products makes the soil so much more beneficial to the end user.

Case studies:
City of Bayswater – have a turf mix with added Bentonite clay to help the turf and recover from stem nematode damage.

Deep Green Landscaping – use Bentonite in their rooftop and garden mixes to give the soil the best chance of holding onto water and nutrients, especially new plantings.

Environmental Industries – adding a small percentage of Bentonite clay to their landscape mixes have proven a winner for them in newly planted areas with fewer plant losses.

Wetting agent with Bentonite clay
Richgro supplies a commercial granular wetting agent that has 50% granulated Bentonite.This provides much more than just holding water and nutrients longer in the soil profile; it is a huge benefit in the long term and the clay will be there forever.

Richgro also make many special mixes for clients for use in landscaping, rooftop gardens, turf topdressing, supressing of nematodes, horticulture and general garden use.


When planting in sandy soil, it is essential to incorporate a clay amendment such as Bentonite. Clay based amendments make the soil more friable and help to hold on to both moisture and fertiliser, thereby saving you money and preventing our precious rivers from excess nitrogen pollution which may cause issues in the waterways.

It goes without saying that our nutrient depleted soils need soil conditioning. Usually a ratio of between 30 and 50% soil conditioner to 70-50% soil is recommended; the amount varying depending on the quality of your soil. Soil improver comes in bags or bulk quantities from Richgro. Manure is also often added to the planting hole, of which I would recommend our Blended manure because of the 3 types of animal manures in the bags incorporated with composted sawdust.
Always thoroughly mix soil conditioner and clay amendments with the existing soil, using water to achieve a chocolate-y loam texture. Never plant straight into a hole with unmixed soil conditioner or compost. Your plant roots will burn and most likely it won’t be long before the plant dies.

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