“... the Latin name for man, homo, derived from humus, the stuff of life in the soil.” - Dr. Daniel Hillel
Composting at Holme Lacy College
The importance of compost is much debated in organic circles, considered by some to be central to soil fertility for others it barely gets a mention. The generally agreed position in the UK is that aerobic composting is important if green waste or wood chips are to be made suitable for applying to the soil. It is worthwhile doing some degree of composting of farmyard manure if soil organic matter levels are low, to control disease and weed seeds and to make the material more friable and therefore more easily incorporated by soil organisms. The composting process itself may vary from turning 2 or 3 time with a foreloader to multiple turning with a specialist turner, inoculation and carefully controlled temperature and carbon dioxide levels. For more information see
http://www.organicmeasures.co.uk/To%20compost%20or%20not%20to%20compost.pdf Good quality farm-yard manure may not need composting if the main aim is to provide more readily available nutrients to the soil.
Christine Jones instead proposes that anaerobic compost is the most effective way of stimulating soil biology. Edwin Blosser made the case at the ACRES conference for the use of very precisely managed aerobic compost and Sandy Syburg argues that compost and its products are invaluable to farming to build soil organic matter and contribute nutrients and the only way of effectively using organic “waste”.
Composting Made Simple – conference presentation
Edwin Blosser http://midwestbiosystems.com
In Edwin’s view compost is central to organic soil management in order to effectively utilise green waste and stimulate soil biological activity.
The basis of his composting technique is the Luebke Controlled Microbial Compost (CMC) system, which has been adopted by some farmers in the UK following the workshops that I organised in 2003 at Holme Lacy College.
His experience is that through aerobic composting following a system of closely controlled temperature, carbon dioxide and moisture (45%) that organic waste can be rapidly converted into high quality compost.
Apart from the mix of organic materials of the correct C:N ratio, some clay is added to help stabilise the product. Edwin also thinks that inoculation is essential, not only that but Edwin uses 3 different inoculants during the rapid composting process, completed in 8 weeks. This is rather at odds with my experience, which is that good quality compost can be made without the need for inoculation. But is the end product the same?
Well made aerobic compost will help build soil organic matter, provide a home and substrate for microbial activity, counter drought, requires less fertiliser, help prevent disease, produce a more friable material, reduce moisture in plants and add and balance minerals.
Anaerobic compost can burn roots, loose nitrogen as gases, and loose energy in the form of carbohydrates.
Edwin gave an example of a farm that increased soil organic matter (SOM) from 2.6% to 2.8 % over 10 years with standard compost. Over the following 10 years SOM increased to 16% with CMC type composting with inoculation. Is this possible? In my experience such rapid increases to such a high level can only be achieved by exceptionally high compost application rates.
Edwin gave another example where after 30 years of 4 inches green waste applied annually the SOM was still only 2%. Replacing the green waste with compost made from the same material the SOM increased to 5.9% over 5 years.
Experiences of a farmer and compost producer
Sandy Syburg farms 300 acres of organic arable crops in South Wisconsin, however his principle business is composting municipal green “waste”, 100,000 tones a year using an aerobic composting process. While perhaps not as controlled as Edwin Blosser’s system he does monitor temperature and carbon dioxide and uses top of the range turning equipment to produce a high quality compost https://www.purplecoworganics.com/farmers/full-cycle-ag-system/
Our discussions at Oconomowoc focused on soil management and the role of compost to supply nutrients and organic matter, stimulate biological activity and make nutrients more available. The basis for compost use is soil analysis; the company offers a free soil analysis service to customers and again they rely on Albrecht analysis undertaken by Mid West Labs. There is no use of plant tissue analysis. The company offers a wide range of compost products to commercial farmers including straight compost and with added rock phosphate, calcium, sulphur, trace elements and humates, liquid products and non-peat growing media for plant raising. Interestingly by adding rock phosphate towards the maturation stage of the composting process, which is enhancing phosphate availability, which contrast with the lock-up that we sometimes experienced in the P Link trials.
Food quality and the health of animals and people underlie the objective of soil management expressed by Sandy and many other organic farmers that I met. The small but significant difference between organic and conventional food in the UK (Reference Quality and Low Input Food, Newcastle University http://www.qlif.org ) is multiplied many times over by the very poor production methods of conventional farming in the US. Washington University have food quality data and Sandy’s view is that soils which have had any mineral deficiencies rectified with minerals of compost will be of higher nutritional value than those that have not.
The common experience of the organic farms that I visited is that soil mineral monitoring is excellent, there is little or no soil biology monitoring except occasionally for earthworms on a few farms, and that inputs of macro and micro elements and stimulants in the form of inoculants and humates, as soil and foliar applications on an annual basis is general. None of the farms that I visited focused on a closed system approach, relying entirely on biological fixation of nitrogen.