Wednesday, March 17, 2010

Soil Myths 1: Turning the Soil

Spending time reading, working, researching vs spending time in various gardens can make me anxious. Watching the destruction of soil structure, loss of nutrients, and degradation of backyard soil is frustrating. Especially when you know it is all through a few misunderstood tips! To dispel some backyard soil myths, I will be undertaking special blogs on Backyard Soil Myths. The first Myth is brought to you by some ex-landlords.

Soil Myth 1: It is best to turn your soil regularly

Spending 4 hours in my garden turning every sod over was not my idea of fun. Not only was it 35 degrees C that day, but watching my careful soil restoration being destroyed with every fork-full was nearly making me cry.

I am a soil rehabilitation expert. That means, I fix soil for a living. Why? To get plants to grow in it for food, oxygen and other ecosystem services. How? I add organic mulches, fertilisers, gypsum, lime and dabble in other soil conditioning arts.

My yard was a mess when we first moved. The soil had poor structure, small water holding capacity and not very good for plants.  The whole area had been mistreated; hard soil from compaction + no water = no plants. So, I came to the rescue and did some soil rehabilitation work. I added all different types of mulches and got some great soil and plants!

Beautiful Healthy Soil = Healthy Plants

I felt so proud having achieved beautiful soil and plants from a bare earth. I was also able to try-out some of my own research ideas. However, when my landlords asked me to 'pull out the plants and turn the soil' when I moved out, my heart fell.

Why? Turning soil exposes soil structure, biology and nutrients to the environment, and causes soil degradation.

Disturbing the soil through turning, cultivation or other practices exposes it to the weather and causes degradation. Soil forms a surface to protect itself from the weather. This surface regulates water, nutrient losses and protects soil biology. Turning the soil destroys this layer, and exposes soil to the environment.

What can happen when it is exposed to the environment?

Soil that is exposed to the environment will erode, loose nutrients and biology, and be less suitable for plant growth. Exposure of soil to rain may cause poor soil structure and erosion. Instead of having nice friable soil that is crumbly and holds lots of water, you will end up with soil that is hard and has little water. Nutrients in the soil will become exposed, and will either be lost as gases into the atmosphere, run off with water or be eaten up by all the soil bugs. Soil biology will eventually die without more nutrients, and there will be no more soil animals regulating soil structure or nutrient cycling. With loss of structure, less soil water, nutrients and biology, the soil becomes less suitable for plants. It becomes degraded, like a dessert landscape.

I must turn my soil!

So, if you have healthy soil, do not turn it! If you do need to turn it for a new crop, make sure you plant immediately after and cover the surface with a mulch (hay, straw, shredded paper). This will limit exposure of soil to the environment and keep it healthy.