How to Make Superior Compost
The Superior Value of Indore Compost
Howard said that finished Indore compost was twice as rich in nitrogen as ordinary farmyard manure and that his target was compost with a C/N of 10:1. Since it was long manure he was referring to, let's assume that the C/N of a new heap started at 25:1.
The C/N of vegetation collected during the year is highly variable. Young grasses and legumes are very high in nitrogen, while dried straw from mature plants has a very high C/N. If compost is made catch-as-catch-can by using materials as they come available, then results will be highly erratic. Howard had attempted to make composts of single vegetable materials like cotton residues, cane trash, weeds, fresh green sweet clover, or the waste of field peas. These experiments were always unsatisfactory. So Howard wisely mixed his vegetation, first withering and drying green materials by spreading them thinly in the sun to prevent their premature decomposition, and then taking great care to preserve a uniform mixture of vegetation types when charging his compost pits. This strategy can be duplicated by the home gardener. Howard was surprised to discover that he could compost all the crop waste he had available with only half the urine earth and about one-quarter of the oxen manure he had available. But fresh manure and urine earth were essential.
During the 1920s a patented process for making compost with a chemical fertilizer called Adco was in vogue and Howard tried it. Of using chemicals he said:
"The weak point of Adco is that it does nothing to overcome one of the great difficulties in composting, namely the absorption of moisture in the early stages. In hot weather in India, the Adco pits lose moisture so rapidly that the fermentation stops, the temperature becomes uneven and then falls. When, however, urine earth and cow-dung are used, the residues become covered with a thin colloidal film, which not only retains moisture but contains combined nitrogen and minerals required by the fungi. This film enables the moisture to penetrate the mass and helps the fungi to establish themselves. Another disadvantage of Adco is that when this material is used according to the directions, the carbon-nitrogen ratio of the final product is narrower than the ideal 10:1. Nitrogen is almost certain to be lost before the crop can make use of it"
Fresh cow manure contains digestive enzymes and living bacteria that specialize in cellulose decomposition. Having a regular supply of this material helped initiate decomposition without delay. Contributing large quantities of actively growing microorganisms through mass inoculation with material from a two-week-old pile also helped. The second mass inoculation at two weeks, with material from a month-old heap provided a large supply of the type of organisms required when the heap began cooling. City gardeners without access to fresh manure may compensate for this lack by imitating Howard's mass inoculation technique, starting smaller amounts of compost in a series of bins and mixing into each bin a bit of material from the one further along at each turning. The passive backyard composting container automatically duplicates this advantage. It simultaneously contains all decomposition stages and inoculates the material above by contact with more decomposed material below. Using prepared inoculants in a continuous composting bin is unnecessary.
City gardeners cannot readily obtain urine earth. Nor are American country gardeners with livestock likely to be willing to do so much work. Remember that Howard used urine earth for three reasons. One, it contained a great deal of nitrogen and improved the starting C/N of the heap. Second, it is thrifty. Over half the nutrient content of the food passing through cattle is discharged in the urine. But, equally important, soil itself was beneficial to the process. Of this Howard said, "[where] there may be insufficient dung and urine earth for converting large quantities of vegetable wastes which are available, the shortage may be made up by the use of nitrate of soda . . . If such artificials are employed, it will be a great advantage to make use of soil." I am sure he would have made very similar comments about adding soil when using chicken manure, or organic concentrates like seed meals, as cattle manure substitutes.
Control of the air supply is the most difficult part of composting. First, the process must stay aerobic. That is one reason that single-material heaps fail because they tend to pack too tightly. To facilitate air exchange, the pits or heaps were never more than two feet deep. Where air was insufficient (though still aerobic) decay is retarded but worse, a process called denitrification occurs in which nitrates and ammonia are biologically broken down into gasses and permanently lost. Too much manure and urine-earth can also interfere with aeration by making the heap too heavy, establishing anaerobic conditions. The chart illustrates denitrification caused by insufficient aeration compared to turning the composting process into a biological nitrate factory with optimum aeration.
Making Indore Compost in Deep and Shallow Pits
| Pit 4 feet deep | Pit 2 feet deep | |
| Amount of material (lb. wet) in pit at start | 4,500 | 4,514 |
| Total nitrogen (lb) at start | 31.25 | 29.12 |
| Total nitrogen at end | 29.49 | 32.36 |
| Loss or gain of nitrogen (lb) | -1.76 | +3.24 |
| Percentage loss or gain of nitrogen | -6.1% | +11.1% |
Finally, modern gardeners might reconsider limiting temperature during composting. India is a very warm climate with balmy nights most of the year. Heaps two or three feet high will achieve an initial temperature of about 145 degree. The purchase of a thermometer with a long probe and a little experimentation will show you the dimensions that will more-or-less duplicate Howard's temperature regimes in your climate with your materials.
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