It is amazing how manure means different things to different people. To many people, it is a waste that must be disposed of, reduced, treated, hidden quickly and efficiently. In India and China for centuries, human manure was a principal source of agricultural nutrients.
"Waste" is a verb, not a noun. It is what you do with manure that makes the difference. An organic farmer recognizes manure as a valuable resource, a reliable and persistent crop that one harvests every day. An organic farm is ideally a mixed farm, in fact the traditional farm of our grandparents and the farm imagined by most urban dwellers.
The organic farmer manages a nutrient cycle that flows from the natural resources (heat, light, air, water, soil, life) to the plants, to the animals and back to the soil again. Since the farm system entraps free energy from the environment, the farm can export food energy at key stages and reasonable amounts such as meat, milk, vegetables, and grain. However, the farm must digest and recycle critical nutrient reserves in the straw, garden residues, and manure. Hence, the farm is a balanced and self-sustaining energy conversion system that utilizes free inputs and earns revenues from the sale of produce. Otherwise, by selling the straw and giving away the manure, the farm becomes a net importer of energy in the form of expensive synthetic fertilizers from fossil fuels. The organic farm without animals is still feasible but requires an extra effort in the form of cover crops for green manure.
Agriculture is the human activity that has the greatest impact on our environment. It is up to us to determine how devastating or neutral that impact will be. There will come a time when environment protection officers will examine the discharge of your tile drainage; the leaching of synthetic or animal nutrients will no longer be tolerated. We already hear of regulations in development that will impose a nutrient management system with a mandatory balance of imported, exported and recycled nutrients. Thus, simply handling and disposing of manure will no longer suffice.
Contrary to popular belief, manure alone does not satisfy organic standards. Organic farmers do not apply raw manure to the garden patch nor to their fields. Raw manure is rather useless and dangerous. It is very volatile; gaseous nutrients will evaporate quickly and water soluble nutrients will run off or leach with the rain. Raw manure is quite toxic to the soil because of the PH imbalance and strong ammonia compounds. The bad smell comes from anaerobic bacteria that obtain oxygen from the sulphates and release sulphur gas. The raw manure will propagate weed seeds and pathogens. The farmer who follows conventional recommendations by incorporating manure quickly only solves part of the problem - complaints from the neighbours. But he/she is wasting resources and creating other problems.
Manure must be composted. Composting is an aerobic process by which microbes and insects digest organic material (manure, leaves, grass, wood, etc.) and convert it to humus. Humus contains the nutrients, especially nitrogen, that are readily available to the plant through microbial activity in the soil. Humus contains structured compounds that will not run off nor leach; it is also high in microbial life that is very beneficial to the soil and the plants. The heat produced in the compost pile will kill most pathogens and weed seeds. The resulting compost has a good soft odour, feels like soil, and looks black. you will hear no neighbours complain about a compost application in the neighbouring field as opposed to the liquid manure application down the road.
An organic farmer manages the manure crop like any other crop. As the corn crop needs heat, water, soil, air, microbial life, so does the manure crop. The farmer will use bedding under the animals to prepare a solid manure that contains the correct carbon-nitrogen ratio so critical to microbial life and decomposition. The straw also provides structure to the compost pile to absorb oxygen and hold the liquids. A manure compost pile is sheltered from the rain in order to manage the moisture level. It is turned periodically to introduce air. The farmer collects and manages the manure for 12 months and then applies the compost to the fields in the spring for maximum productivity. The only risk with good compost is over fertility that will promote pigweed and other weeds.
If you think of manure as a waste to dispose of, then stop wasting and harvest that crop properly - it is your most valuable resource. By the way, stinking manure and liquid manure may be common, but they cannot be described as normal agricultural practices.
A contribution by Tom Manley
President of Homestead Organics