Soil Types & Weeds

Soil Types

• Different soils have different percentages of certain sized particles. The percentage of sand, silt and clay that a soil contains determines its texture. A soil with lots of sand will be loose and well drained. It will have poor structure and a low water holding capacity.

  Soils with lots of clay are dense, have a high water-holding capacity and well developed soil structure. Soil structure is how soil particles cling together. Good soil structure is not compacted and is full of small aggregates of soil which plant roots can cling to.

  Levels of organic matter also define soil types.Organic matter is the material from decayed plant and animals. The amount of organic matter in a soil is the main indicator of soil fertility. Soils with poor soil structure and low organic matter are more likely to be difficult to grow plants in. Soil types that become bare are more likely to have weeds.

Compaction

• Natural soils are loose. Organisms like worms and ants are constantly lifting and borrowing into the soil. Plant roots separate soil particles and allow water to drain into the ground. Good soil structure is important for a healthy exchange of gasses into and out of the soil. When a soil is subjected to any vertical pressure it becomes compacted. Human activity is the main cause of damaging soil compaction. Foot traffic destroys soil structure when it is concentrated over a certain area.

  The most damaging compacting is caused by vehicles. A compacted soil is less able to support the normal types of plants you would like to grow. Weeds are adapted to growing in adverse conditions. If you have lots of weeds growing on your soil it may be compacted. Aerate the soil to make it less compacted.

Soil pH

• When the pH of a soil is imbalanced certain plant nutrients become unavailable to the plants. When plants become weak from poor nutrition the soil they are growing is more likely to become dominated by weeds. Weeds are designed to have deeper roots than most of the plants you are trying to grow. The malnourished plants provide bare spaces in the soil where weed seeds can start. Weeds get more nutrients from their root system and reach areas of the soil that may not have an imbalanced pH. By keeping your soil and the right pH level for your region and the plants you are growing you can keep your plants strong so that they can resist invasion by weeds.

Water

• Make sure the plants you are growing have sufficient water. If your lawn is not getting enough water bare spots can develop which are ideal places for weeds to begin growing. Well drained soil types with lots of sand will need watered more frequently. Water longer and less frequently. For example, instead of watering twice a day have one watering that lasts twice as long. This will make the plant roots grow deeper and help keep weeds from getting started.