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Let's grasp the GM nettle
2:13pm Friday 23rd September 2011 in Farming
With most harvesting now completed, the race is on to get the fields prepared for the planting of next year’s crops.
It is a hectic period of the year as hedges are trimmed, the ploughs or cultivators are hard at work and basic fertilisers are applied.
Whether plants are being grown organically or conventionally, in the garden or in the field, they need food.
Fertilisers are used to enhance general fertility and to replace chemical elements removed by previous crops.
Chalk is used to correct soil acidity, but the main food elements required are nitrogen, phosphate and potash.
Phosphate and potash are generally derived from rock deposits and, being fairly insoluble, they can be applied at this time of year and will last for two years or more.
With the world’s farmers trying desperately to increase production, fertiliser prices have rocketed and almost any industrial byproduct is now being sold as fertiliser.
Basic slag, bone meal, waste paper, sewage sludge, and even ash from power stations is being spread on fields at present.
Most of the nitrogen used today is “synthetic” or “artificial” ammonia. In this form, it has the great advantage that it can be spread accurately as granules or liquid and, to avoid leaching from the soil, it can be applied at exactly the time plants require it.
More traditional forms of nitrogen fertiliser are farmyard manure, or sewage sludge. Nitrogen is released much more slowly in this form, so it can be applied in the autumn and it improves overall fertility, but it is not so easy to apply and, of course, it smells, so it needs incorporating into the soil.
The most interesting source of nitrogen comes from plants themselves. Some 80 per cent of the air we breathe is nitrogen, but it is not available to plants until converted to nitrates or ammonia.
One group of plants, called legumes, has an extraordinary liaison with some bacteria which live in their roots and convert nitrogen from the air into nitrates.
Legumes, therefore, need no artificial nitrogen and when they are harvested and the roots return to the soil, its fertility is enhanced.
For centuries, farmers grew clover, peas and beans for this purpose.
This truly is a sustainable source of fertiliser and scientists now think that, by using GM technology, they can breed leguminous strains of grasses and cereals.
Surely it is time for the UK to set outdated prejudice aside and instigate proper GM crop trials.