Typically, chicken litter is considered a livestock manure requiring periodic removal. Litter from broiler operations usually is taken out of the barns at the end of each flock cycle. The litter is then sold “fresh” or composted. At A & J Farms, a low-rate method of composting chicken litter within the barns is putting a new twist on manure management.
Jeff Weisel, the managing partner in A & J Farms, oversees the total farm property, including litter management, farming the crop land, and environmental quality. Before the start of a new growing cycle, barns at the 14 farms are carefully cleaned out and pressure washed. The clay floors are so hard packed that cleaning does not disturb them. Cleaned floors are covered with a mixture of sawdust or fine chips from kiln-dried oak and poplar, and a remainder of ten to 15 percent of the composted litter from the previous litter cycle.
The birds then are introduced as peeps. The barns at the 14 farms are initially subdivided so that the peeps take up only the first 100 feet. After they grow a bit, the entire barn is opened up for the chicks to wander. After seven weeks, the chickens reach their finished weight and are removed for processing. At this time, the litter is not removed as would happen on most farms. Instead, it is rotary tilled and carefully leveled. The litter has to be very level throughout the barn so that the distance between the litter and the automatic waterers is uniform.
The cycle of raising a flock and then rotary tilling and leveling the litter is continued for a total of five to seven times, when the litter is finally removed and a new cycle is initiated. Throughout the entire cycle, the litter is managed by a low-rate composting process. Temperatures in the litter are generally in the range of 37° to 44°C. During the first few flock cycles, the litter increases in volume and nutrient content. By the finish of the fourth flock, the sawdust is fully broken down and is no longer visually apparent. After the fifth flock, nitrogen concentration in the litter reaches its highest value, and with subsequent flocks, the nutrient concentration actually decreases while the litter volume continues to increase. (This occurs because the rate of litter decomposition starts to reach an equilibrium with manure addition, whereas the ash content continues to increase on a constant basis. The ratio of ash to organic matter rises, so while total nutrient values in the barn litter increase, the concentrations decrease.) At the end of seven flocks, litter depth reaches eight to nine inches.
To support the low-rate composting process, litter moisture contents are maintained in a 19 to 25 percent range. While this seems low for composting, it has been demonstrated that such moisture contents are well able to supply the microbial population’s physiological need for water, and only slow composting down by limiting substrate colonization via water films. Colonization limitation at low moisture contents can be alleviated by mixing, which is carried out in the barns by rotary tilling and by the continuous scratching of the litter by the chickens. One could think of the chickens as an army of small compost turners.
Water and feed are provided for the birds through automatic lines. Management of flock watering is crucial. As the birds grow, the watering lines are continuously raised above the floor so that the birds need to reach up to get a drink. This prevents the birds from touching the waterers and releasing water onto the litter. As peeps can’t reach up very well, a compostable paper is used underneath the watering lines to prevent water from dripping into the composting litter. The paper disappears into the litter after a few days.
Compost Quality And Utilization
Quality of the composted litter when it is removed from the barns is highly uniform. Values of N:P:K run close to 5:4.5:4. Such high nutrient values permit this litter to be considered as an organic fertilizer. Having a high nutrient concentration in a fairly stable composted material is unusual, but then again, the composting process at A & J Farms is rather unconventional. In Ohio, which has a large poultry industry, Ohio State University researchers are looking at poultry litter as an agricultural fertilizer and developing usage recommendations.
A & J Farms is selling its composted chicken litter for agricultural land application, and getting a farm gate price of $12/ton. Finding buyers for the composted litter has not been a problem.
A & J Farms also has used the composted litter to reclaim strip mine soils. A good portion of the farm in 1989 was barren strip mine spoils. So far, over 200 acres of those areas have been reclaimed and now are very productive cropland.
It was found early on that chemical fertilizers were not good for reclaiming the spoils areas because they introduced too much salinity. In fact, chemical fertilizers are not used on any part of the farm. Nutrients and organic matter are added to the field soils through an application of composted poultry litter every two or three years, three to five tons to the acre. No more nutrients are added to the soil with the compost than the total amounts required for a particular crop. Weisel believes that this natural approach to soil management has led to very productive crops, a reduced incidence of crop diseases, and an absence of nutrient contamination of ground and surface water. Soil amendment with compost has not only improved overall crop economic returns, but also continues to improve the soil’s ability to produce good crops.
Nitrogen management in litter can be troublesome in that microbial activity releases a good deal of nitrogen as ammonia. High levels of ammonia can harm chickens, and the loss of nitrogen reduces the fertilizer value of the litter. Although common at other chicken operations, A & J Farms does not use any chemical control for ammonia reduction in the litter. Levels of ammonia are not a problem, since the composting litter does not release as much ammonia as single-cycle litter systems. Analyses indicate that less than half of one percent of the nitrogen in the finished compost is in the ammonium/ammonia form. Finished compost absorbs ammonia, and the litter may be held long enough for significant development of microbial populations that can convert the ammonia to organic forms. The deeper litter may become more chemically suited to undergoing reactions wherein ammonia and carbohydrates form organic nitrogen compounds.
There are other grower advantages to in-barn composting litter. Composting litter gives young chicks a warmer floor in the winter, and a drier floor all year around. Chickens stay very clean. Much less new litter has to be purchased. Composting litter also provides nutrients such as vitamin B-12 to chickens.
As a result of its system, odors related to litter are not a problem at A & J Farms. The only real odors in the barns are the body odors of the chickens and the smell of ammonia. The composting litter does not attract flies or other insects, and there are no screens to keep them out of the barns.
Good Hygiene And Healthy Birds
Of course, major goals of litter management are maintaining good hygiene and raising healthy birds. The rationale for removing litter at the end of each flock cycle is to decrease pathogen levels and prevent disease spread to subsequent flocks. Yet research has demonstrated that composting litter suppresses various diseases in chickens, and that chicks raised on composting litter suffer significantly less mortality than those on fresh litter. In 1959, a study at the Ohio Agricultural Experiment Station demonstrated that a number of chicken pathogens had much shorter survival times in composting litter compared to fresh litter. Pathogen kill was attributed to higher levels of ammonia and higher temperatures.
We know now that pathogen reduction in composting materials is more complex. While high temperatures or ammonia concentrations obviously can kill pathogens, biological antagonisms also can have a strong effect on pathogen survival. For example, Salmonella is repressed in compost by antagonistic bacteria and actinomycetes, and actinomycetes suppress Shigella. Compost nutritional factors also can have a significant effect on pathogen growth and disease (see side bar).
At A & J Farms, it has been observed that the highest chick mortality is always in the flock raised during the first litter cycle, which they refer to on the farm as “new litter syndrome.” Normal mortality at A & J Farms is a remarkable 1.5 percent, which is significantly lower than the commonly accepted rate of five percent for broilers. Weisel states that at A & J Farms, there has never been a disease epidemic in the chickens raised on composting litter.
Overall, Weisel notes that his goal is to leave A & J Farms more productive and profitable while having only a beneficial impact on the environment. The composting litter system fits right into his philosophy by lowering production costs, raising healthier chickens, and promoting beneficial reuse of chicken manure nutrients. By Frederick C. Miller.