Monday, November 17, 2008

Soil simplified - Q&A


Can you give some background information on soil chapter? What is soil made out of? Why do we talk about soil health?

Many thanks,


Thanks Kane.

Sustainability in reference to soil…

Sustainability is protecting and improving what’s there - so leaving the soil after 10 years of farming in better condition than what it was when you began.   Obviously if the opposite takes place then you’re only able to farm for a short period of time before you exhaust that soil’s ability to farm.

Measuring soil health is complicated. The McLaren Vale Sustainable Winegrowing Australia programme asks questions about soil organic matter, pH, salinity and erosion. All of these are component factors defining and monitoring a healthy soil.

Soil is a mixture of organic matter, air, water and minerals.

Your soil is made up of 4 materials.

1) Minerals - Clay or sand particles weathered down by various processes.
2) Air - Nitrogen, Oxygen, CO2 and other gases.
3) Water.
4) Organic matter - living things and their waste products.

Bacteria - microbes that live in the soil. Bacteria don't help soil structure as they stick onto the sides of minerals in the soil.

Fungi - also microbes that live in the soil. Fungi are very beneficial to soil as they bind the minerals in your soil together. Some types of fungi also join with plant roots and help extend your vines root system.

Biota - all of the living insects in your soil, earthworms, dung beetles, slaters to name a few.

In drought years you have little control over the water your soil holds. Even with irrigation the vine mid row is now dry and your vine roots in this part of the soil are not active. What you do have an influence on is the amount of organic matter in your soil. The activities of these microbes help by building humus.
Humus is organic matter which has reached a point of stability, where it will not break down, and if conditions do not change, remain as it is for many years.
Many of the key processes in BioDynamic farming / Sustainable farming are designed to boost the amount of organic matter (chiefly humus) in your soil.
Organic matter can be measured by the amount of organic carbon is in your soil. Level of 2% are common in McLaren Vale. Ideally growers should aim to double the amount of carbon in their soil as a start. This soil will benefit you by holding more water and will need less fertilisers because what is already present in the soil will be more available.

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