Manure, rotation, and pathogens

22 Jul 2013

At ... Europe's first farmers, some 8000 years ago, used manure on their fields. It has always been assumed manure was not used until the Iron Age/Roman period but enriched levels of Nitrogen 15, a stable isotope abundant in manure, has been found in charred cereal grains and palaeo seeds (peas, beans, lentils) from 13 different Neolithic sites across Europe (including Britain) between 6000 and 2400BC. Manuring is a long term process - it takes several years for the land to benefit fully from manure. It is not a quick fix (although it does improve soil structure on a shorter timescale). This discovery upturns some previous assumptions about the first farmers to enter Europe as it is commonly said, and read, that they used slash and burn methods (producing wood ash that quickly provided nutrients, but washing out quickly and therefore requiring a search for new land to colonise). This is how the archaeological record, at the time, was interpreted. Evidence of landscape fires and rapid migrations of people were found, especially from the Balkans and up the Danube Valley. The movement was in a series of leaps rather than just piecemeal recolonisation of the loess soils. It was always a rather tortured theory - why would people set themselves, on a regular basis, the task of chopping down and burning large swathes of virgin forest? What else might have caused the landscape fires and in turn, caused people to migrate in a series of stages? Landscape fires can be caused by other means - and we have been banging on about this as evidence of Tunguska like episodes in the past - but on deaf ears. The message has not yet reached mainstream but it is relevant. Archaeologists need to think outside the box. Glib and unimaginative explanations are not necessarily the right ones.

Another firmly held idea also found wanting as Nitrogen 15 found in human skeletons has always been attributed to a diet high in meat and dairy products - which turns out to be another fallacy (or exaggeration). A connection made with cereals and pulses suggests very strongly that early farmers were primarily practising arable - and not consuming their herds at the rate imagined in earlier deliberations. The consumption of cheese and milk depended on lactose tolerance and may again be highly exaggerated. Modern diets are very high in dairy products, and cheese is a staple of the sandwich and the salad, of pizzas and welsh rarebit (a Welsh pizza but tastier if you use the right kind of bread), and numerous chef concoctions. Peasants lived on vegetable gruels for thousands of years, with just the rare piece of meat. No doubt they did eat cheese which was more readily available to them - and wild game. Interesting subject - what is healthy in the eyes of one kind of researcher is anathema to another. In the 18th and 19th centuries roast beef or lamb became a weekend staple of the dinner tables of the middle classes, and this was adopted by the former peasants, the new working class working in the factories of the industrial revolution. Meat became a major item of diet to everybody - not just the wealthy. People's longevity increased with a better diet, and they became bigger and stronger. I wonder what a diet of pizza and chips will produce over time, or tofu and mung beans?

At ... an interesting post from a paper in The ISME Journal (Nature) on crop rotation - which again is supposed to go back to Roman times (but again this is only an assumption and may be an older practise). Changing where specific types of crop grow year by year in order to avoid a build up of pests and disease is a well known organic farming (and gardening) method - and the research was done by the John Innes science centre (so is not particularly green and organic as in wonky carrots). Crop rotation, it has been found, appears to enrich the soil with bacteria, fungi, and protozoa (microbes in the growing medium, the upper layer of soils) which help plants aquire nutrients, and grow, and also protect them against pests and diseases. Confirmatory science - confirms an old wives tale, or the beardie gardener with the best plot on the alottment site, and the biggest leeks.

At ... we learn that the pathogen that caused the Irish potato famine is still around - and potentially a problem (in wet summers) (published in Nature Communications).

At .... French scientists report in the journal Science that two newly found viruses are twice as large as previous big ones. These represent a new life form as they are quite different from the average virus. However, viruses do not necessarily make people sick - there are good ones as well.

Lastly, at ... the EU has ganged up with dodgy NGOs (you know who) to encourage healthy diets - or what they see as healthy (and sustainable) and that means eating less red meat (where is all the manure going to come from to grow the veggies nice and fat and plump). According to some of the research (by big brother, no doubt) peoples dietary habits will have to radically transform - as 'we have ways of making you' change. Meat and dairy products are on the way out we are confidently told by the sons and daughters of wealthy westerners (meanwhile, the Chinese are grabbing all the steaks). Cheese and tomatoe sandwiches will become bean salad baguettes. No egg and cress but you can have some lettuce with your tomato in a nice wrap around thingie - dripping with sauces. The question is what are they going to do about all that meat as burnt offerings at barbecue suppers?