It has been around since time began; valuable in ancient and modern times as a source of plant nutrients and soil organic matter. Valued for its use in the home garden arena, and on the farm where it can benefit output from crops, hayfields and pastures. It goes by many names but poultry producers generally call it litter'. Whether a scientific definition in the strictest sense or not, litter is a combination of bedding materials such as wood shavings, peanut hulls or recycled paper products with poultry manure. Strictly speaking, mammals produce urine and faeces but birds combine it into one dropping and it is called excreta'. By the way, the white cap is the urinary part of the excreta.
Many individuals participating in the poultry industry producers, corporate CEOs and professional engineers have attempted to quantify poultry poop'. Environmental impacts, concentrated production areas and regulatory considerations are all legitimate concerns and provide the poultry producer with the task and challenge of ensuring that the litter is properly handled, stored and applied as a valuable source of fertiliser. Unfortunately, the bird is a biological system and a certain amount of variation and unpredictability is often inserted into the equation. Mechanical systems are much more reliable and predictable than any biological system.
The quantity of litter produced
Estimating the amount of litter produced by broilers has been difficult owing to a large number of variables. Type of bird, market weight, number of flocks, field conditions, time of year and litter moisture are among the many variables that must be considered. Several years ago, field tests were conducted by Biosystems Engineering at Auburn University in the USA in co-operation with Alabama Co-operative Extension System country agents to determine the amount of litter generated on a typical Alabama broiler farm. In this setting, 2-kg broilers were grown in houses measuring 12 metres by 152 metres. Pine shavings to a depth of 6.4cm were used as the bedding material. Additional shavings were placed in the brood area of the house between flocks.
In the field test, eight successive broiler flocks were grown in the houses during the course of about one year. The amount of litter obtained from a single house was weighed during total clean-out to the ground, and litter removed between the flocks was also recorded. The total amount of litter produced from one house and its relationship to production parameters are shown in Table 1.
Producers are now faced with mandatory nutrient and waste management planning as a result of impending environmental regulations in many countries. Information obtained from this field test can be useful in the preparation of a nutrient management plan or for sizing a litter storage structure.
Chemical composition of the litter
Obtaining the fertiliser value of litter is another variable that the poultry producer must deal with. It also depends on a number of factors, including the type of bedding material used, the number of flocks grown between house clean-outs and moisture content. In the USA, producers are required to sample their litter and have it analysed at least once in three years, depending on location. The chemical analysis of the Auburn litter experiment is presented in Table 2, compared to average values for the region. Samples submitted to the Auburn University Soil Testing Laboratory have yielded a wide variation in average values for nitrogen, phosphorus and potassium, and this supports the need to test poultry litter samples for each farm. However, producers can do an acceptable job of land application assuming an average analysis of 3:3:2% for N, P2O5 and K2O, respectively, for fresh litter applied directly from the house.
Poultry manure is an excellent resource that should be used in a similar way to commercial fertilisers. Always test the soil to determine the amount of nutrients needed by the crop for your soil type. The best advice that can be offered to broiler growers is to estimate and record the amount of litter that is being spread or moved from the farm and to submit soil and litter samples regularly for analysis.