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It is good to remember the analogy between deep litter and a compost heap when choosing litter materials. In the compost heap, carbon and nitrogen sources must be in balance. (A ratio of 30:1 is recommended when the pile is assembled). If there is too much carbon, the heap remains “cold”—that is, the microbes have insufficient energy from nitrogen sources to thrive. If there is too much nitrogen in the mix, however, the microbes cannot utilize it fast enough, and much of it converts to ammonia (a volatile gas of nitrogen and hydrogen) which is lost to the atmosphere rather than being converted to more stable forms usable by plants.
The major difference in the initial composition of litter is that the proportion of carbon in relation to nitrogen should be much, much higher—indeed, the higher the better. Poultry (especially chicken) manure is a potent source of nitrogen, so we must ensure that the initial mix has enough carbon to absorb a great deal of nitrogen (poops) before the ratio gets low enough to start spontaneous generation of ammonia. As in the compost heap, ammonia production signals a decomposition process out of balance.
When choosing organic materials for the litter, physical as well as chemical (percent carbon) properties must be considered. Materials that will “fluff up” easily by chickens’ scratching are preferable to those that mat down and resist aeration. We should use what is easily and cheaply available to us. Almost any non-toxic, high-carbon organic material is suitable. I have a neighbor who prefers to rake up and dispose of the abundant “harvest” of leaves from the many oaks on her place—she’s even willing to haul and dump them at my place, so that is my preferred material for litter. It may be that litter materials available to you are byproducts of crops grown in quantity in your area—rice or buckwheat or peanut hulls, for example, or chopped corn cobs.
Wood shavings make excellent litter, so long as they are cheap enough and we avoid black walnut and aromatic woods such as cedar. Wood chips are good (and often free for the taking from tree and brush clearing companies), so long as they are well aged—they should not be used “green.” An excellent example of successful use of wood chips is Joel Salatin’s “raken” (ra-bbit and chic-ken) house: Cages for the breeding rabbits are suspended over a 12-inch litter of coarse chips. The chickens work the urine and droppings of the rabbits, as well as their own, into the litter. With such a deep, high-carbon litter, Joel only has to clean out once a year.
As for sawdust, it too must not be used fresh, though well-aged sawdust is a possibility. I have used sawdust from time to time in the past, though it is not my preferred material. It tends to pack down and resist aeration more than coarser materials. If mixed with looser materials, however, it will remain better dispersed and aerated in the litter, and will contribute abundant carbon. (The C:N ratio is as high as 500:1.)
I prefer to avoid straw, which in the slightly moist conditions of litter over earth can support the growth of Aspergillus molds, the spores of which are not good for either birds or us to breathe. I’ve received reports from a number of poultry keepers, however, who use straw over earth with no problems. I do use straw in a wood-floor building I use for my breeders during the breeding season. In this case, the litter remains dry, and does not support the growth of molds.
Please note that certain organic materials do not make effective litter, usually because the nitrogen content is too high to effectively balance the manure being laid down. Examples are hay and the plant residues from threshing soybeans.
The great thing about deep litter is that the chickens do most of the work of manure management. However, a few management practices are required of us as well.
A litter outgassing ammonia is essentially poisoning the air our flock is breathing. Breathing ammonia damages the sensitive mucous membranes of the lungs, and leads to vitamin imbalances in the system and toxic reactions in the liver. Thus that first whiff of ammonia must not be ignored—it is our signal either to clean out the litter, or to add more high-carbon materials.
If you are not building your chicken shed from scratch but using an existing building with a wood or concrete floor, that’s okay. A deep, loose, organic litter is still the best manure management choice—it will still absorb all the poops the chickens incorporate into the litter. In this case, however, you don’t get as much “composting” effect because the litter is so much drier, and microbial populations not as diverse and active. You may find that you get that whiff of ammonia sooner than in an earth-floor litter, and have to clean out or add more carbonaceous material a bit more frequently. Also, since the litter has not had as thorough a decomposition, such a dry litter should be processed in a compost heap before use, to avoid “burning” crops with forms of nitrogen they cannot use.
When cleaning out the litter, it might be a good idea to leave a bit in place, in order to introduce active microbe populations into the fresh litter material. (Such “inoculation” is probably less needed in the case of an earth floor, which serves as a reservoir of microbes.)
Be generous with the amount of space you allow your birds. Joel Salatin observes—and my own experience bears this out—that five square feet per mature chicken is ideal. At this stocking density, all manure laid down will be incorporated by the chickens themselves. At four square feet, there will be some “capping” (build-up of a solid layer impervious to the flock’s scratching), usually under the roosts. At three square feet (still two or more times the space alloted in commercial operations), there may be capping over most of the litter surface. You should break up capping as soon as it occurs, using a spading fork. Once you have broken capped material into chunks and turned them over, the chickens can scratch them apart.
The litter should never be wet. Wet litter is anaerobic (lacking oxygen), a condition conducive to certain pathogens, in contrast to decompositional microbes, who thrive with abundant oxygen. Should wet spots develop—for example, around the waterers—again use your spading fork to disperse the soaked material out over the rest of the litter, where the scratching of the birds will dry and aerate it. (Don’t be concerned about a little water, however. I often swish out the rims of waterers onto the litter in order to rinse. The resulting increase in moisture, if not excessive, actually benefits the microbial processes in the litter.)
Waterfowl are a special case. Since they do not scratch, they lay down an accumulating layer of quite wet droppings. Either bring the spading fork into play again (only this time doing all the work of turning and dispersing yourself), or—my usual choice—simply allow the chickens and waterfowl to share the same space, and the chickens will provide the service of turning in the waterfowl’s droppings.
In the best of circumstances, waterfowl are pretty sloppy with their water. The best choice is to water them outside the poultry house. Since they are quite cold hardy, you can do this even in winter. If you have to water them inside the winter house, prevent soaked litter with the sort of catch basin described and illustrated in “The Homestead Waterfowl Flock”.