Some advice for dealing with the Valley’s hard soil

Acommon problem with soil in the Antelope Valley is that the soil can be really hard. Water will not soak into the soil and when digging a hole, the shovel seems to bounce off the ground.

It is more important today to make sure that when you water, the water can soak into your soil and not run off. Some people blame the problem due to having clay soil. However, the soil in the urban areas of the Antelope Valley has very poor soil structure.

In tract homes around the valley, there may have been good soil prior to building. In the process of building homes, the soil is graded, packed, watered and packed some more. This reduces the pore or air space in the soil from the normal 50% to less than 10%.

This makes the soil denser and harder.

Removing air space from the soil prevents the soil from expanding and contracting. When the soil cannot soak up water, the water pushes against the soil particles, making the soil expand, and the soil shrinks when it dries. This shrinking and swelling of soil can cause your house to crack. Reducing the pore space lowers the shrink-swell potential. This is great from your home and very bad for your garden and landscape.

Many sources suggest adding gypsum to your soil to improve soil structure. This improvement helps the water to move into your soil. Gypsum will not break up soil compaction. A rototiller or turning your soil with a shovel is the only way to break-up compaction. Gypsum is used to improve the soil structure when the problem is caused by too much sodium in the soil.

Soil structure is the arrangement of sand, silt and clay particles into small groups. This smallest group is called a ped. Several peds may arrange into a larger structure called an aggregate. Several aggregates may combine into a larger structure called a clod. Most of you are familiar with clods, because you have probably thrown one or two in your lifetime. The key to forming these structures is organic matter. Organic matter is often called the glue of the soil, because it ‘’glues’’ the sand silt and clay together into the different structures.

As important as the structure of the particles (sand, silt and clay) is for the soil, the spaces between the particles are more important. When your soil has poor structure the spaces or pores are very small. As structure improves, the total pore space stays the same, but the size of the pores increases. The larger the pore space the easier water and fertilizer can be absorbed by your soil.

Since organic matter is the glue of the soil, it is a very important component. If your soil lacks organic matter, it cannot form peds. The clay particles move toward the soil surface, followed by silt with sand on the bottom. With clay on the surface it forms a barrier that is hard for water to penetrate. Because of the clay surface many people feel they have clay soil, but in fact just have poor structure.

If you have a lot of organic matter in your soil and still seem to have poor structure, it could be caused by high sodium levels in your soil. There are areas in the Antelope Valley that have high sodium levels; most are in low areas (old ponds/lake beds) of the valley. Some may be causing their own sodium problems by dumping their spa water on their garden or landscape. Most spa chemicals are high in sodium.

Just like laundry detergent, the sodium in the soil breaks down the organic matter, not allowing the organic matter to form structure. If your soil is high in sodium you need to add gypsum or gypsite. These products help replace the sodium in your soil, allowing the soil to form structure.

The other problem is that the soils of the Antelope Valley are very low in organic matter. No or low organic matter means no soil structure, again gypsum or gypsite will not help this soil.

Adding compacted soil together with no organic matter and you have very poor structure. Adding gypsum or gypsite again will do very little to improve these soils. Gypsum will help improve a sodic soil, however for most soils in the Antelope Valley a good dose of organic matter rototilled into your soil is the answer to improve your soil structure and improve water going into your soil.