Organics. A note of caution.

Over the past year or two a lot of allotment growers have had to deal with the problem of spreading stable or farmyard manure on their land only to find that the muck was contaminated with aminopyralid  herbicide. This herbicide is used by farmers to control weeds in pasture or in fields that are going to be cut for hay or silage. It does no harm to the stock who ingest traces of it in their feed but of course the aminopyralid is passed through the system of the beasts and acts as a growth suppressant when the manure is spread on the unsuspecting allotmenteers plot. The result can be a wasted growing season.
On the face of it this all looks like further evidence that the full organic method of agriculture is the only one that can keep us happy, healthy, safe and sound. If only it were that simple.
The discovery that nitrogen fertiliser could be industrially manufactured was to revolutionise agriculture and lead to a satisfying increase in productivity. Yields increased yet further with the introduction of compound fertilisers and the widespread use of pesticides. Of course everything comes at a price, and the price in this particular case was the environmental damage that is only too well known. But the reality is that while it's perfectly possible to produce food without resorting to "artificial" fertilisers and chemical pesticides (we have been doing it since Neolithic times after all) the yields are considerably reduced. It's also perfectly possible to keep livestock outside all year round; to have cattle tramping about in a sea of mud rather than over-wintered in barns, and some campaigners would like farmers to do just that,  but it's not the most efficient way of doing the job. This is not an argument in favour of the worst practises of agri-business but it has always seemed to me that growing crops and keeping livestock are areas of life where ideology is best left outside the gate and we just take with us a hearty dose of pragmatism.
Ecologists are fond of talking about an ecosystem being able to "support" a given species population. Thus an increase in snowshoe hare numbers will support a larger Canadian lynx population, farmers leaving wide field margins and hedgerows will support a bigger population of songbirds, and so on.
Before we are too dismissive of modern agricultural methods we would do well to ponder what happens to those members of a population that an ecosystem, or an agricultural system, can not support. They simply starve to death.