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Rehabilitating former orchard
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Rehabilitating former orchard
My wife and I have acquired an active apple farm acreage of 1.9HA in NZ. We have decided to remove the existing apple trees and return the environment to its original condition with native trees, grasses etc. The farm has been used as a commercial apple farm for the first 40-50 years and has been sprayed with commercial sprays, the soil is of clay nature and near an estuary. What would be the best treatment for the land to help remove the toxic chemicals, and help restore the land - eg herbal ley? Is there a preferred method and time for removing apple trees? What do you need to take in to account once the trees have been removed, eg moisture retention etc. Are there any uses for the existing trees, apart from firewood. eg, can you grow another type of tree using the existing root structure?
Charlie Lewis

For nearly a century pesticidal sprays have been used in apple orchards.

Some of them are inorganic chemicals such as the copper containing Bordeaux mixture and copper oxychloride or there are others like lead arsenate.

Others belong into the group of synthetic chemical sprays such as chlorinated hydrocarbons (including DDT) or organophosphates.

Anything of a synthetic/organic nature can potentially, eventually be broken down or decomposed in the soil as a result of biological activity. The main principle is to provide plenty of food for microorganisms in the form of organic matter. Fresh, green material seems to be the most efficient form. Of course, it is also important to generally maintain soil conditions at an optimum for biological activity: keep soil moisture between 50 and 100 % of field capacity, pH between 7 and 7, avoid compaction/drainage problems.

Residues originating from the inorganic chemicals used in the past are a different story. They don't break down, can accumulate and be taken up by crop plants. The plant uptake of copper and lead appears to increase with increasing acidity. Increased biological activity can also help mobilise these heavy metals. In order to reduce this risk it was found that liming decreases plant concentrations of these toxic elements (maintain the pH as high as the crop allows).

However, arsenic uptake is mainly unaffected by acidity changes.

Normally copper, lead and arsenic contents in vegetables grown on former orchard soil wouldn't exceed established standards. But if you are highly self sufficient and have a badly contaminated former orchard soil there could be a problem (especially for children who might be playing on this and may eat some dirt).

A soil test analysis to establish the exact load of contamination is recommended.

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