Sustainable fertilisers for food crops

Composting to save the planet. 2.  It is about £ money?

Mycorr 2.

Mycorrhiza, the soil fungi with the secret of recycling agricultural and urban waste to land.

Did you know that 1 tonne of Nitrogen nutrient (equivalent to 3 tonnes of ammonium nitrate), made in a modern USA factory, will take 21,000 kW h to manufacture and deliver?  (Yes, no mistake, twenty one thousand “units” of electricity.) Most of that electricity will have been produced by burning hydrocarbon fuels.  Now, farmers can make their own fertilisers.

Generally speaking, if the material is of plant or animal tissues, it will have enough nutrients to react reasonably naturally in a compost process. In most environments, there are plenty of micro-organisms and of a wide enough range of species to operate the process. If there is not enough Oxygen, the process will go anaerobic, become odorous and slow down. If there is not enough water, the material may well go dark in colour but the process will be incomplete and will start up again when the material is incorporated into the soil after spreading(8)(9). This may not matter unless there is a shortage of Nitrogen and, in such a case, the micro-organisms in the soil may preferentially use the easily available Nitrogen in the soil to build their own bodies in order to attack the energy source (the Carbon) in the added compost. Farmers sometimes call this “Nitrogen starvation”. The Nitrogen is not lost and will be available to the crop at a later date when the biological activity of the soil catches up with balancing the Nitrogen status of different fractions of the soil. This was described in a composite form in “The Straw Manual” (1). Previous to this date, farmers in the UK faced a ban on burning straw behind the harvester and it was necessary to find out how farmers could incorporate unwanted straw into the soil without high costs and/or loss of yields. That book collated the available research from world-wide sources and showed that the soil will live quite well with what might appear to be enormous imbalances (as with the high Carbon content of cereal straw) provided it is given a little help and time. The basic rule when changing to a system which involves putting large amounts of organic Carbon into a soil is to add enough Nitrogen fertiliser in the first year to allow the soil micro-organisms to build the protein of their own bodies, allow a little less Nitrogen in the second year and less or none by the third or fourth year. After that the soil system will cope because the added Nitrogen does not leach out and the soil micro-organism population has changed in species and population numbers to give the biological activity required to deal with the new regime.

A compost process is basically the same. It is worth going back to the basics of composting for a moment; the four needs of feedstock, micro-organisms, moisture and Oxygen. It might help to add “time” at this point. If one of these basics is either not there, or not in the right quantity, then the process will change or slow down. For example, if there is not enough air, the process will slow down and either stop or go anaerobic which will give off a bad smell. If there is no change of gases, the process will eventually stop. Similarly for water; lack of it will slow the process eventually to the point of cessation. Exactly the same applies to the other two inputs of feedstock (obviously) and micro-organisms (less obvious but quite interesting).  Want to make your own from urban wastes and make cash out of it, try the second book (2) listed below.

  1. “The Straw Manual” was written by myself and published by Spon, 1985 but still available from Amazon.
  2. Similarly, I wrote “How to make on-farm composting work” and published it through MX Publishing, 2009.

Bill Butterworth 28 Oct 15

P.S.  I plan that every mid-week Tuesday or Wednesday depending on appointments away from base, I will run a blog piece on sustainable agriculture, farming, wastes and environment.

“The Straw Manual” was written by myself, published by Spon, London, 1985.