Based on the data shown in Table 2.13.1, the annual production of livestock waste in Japan was calculated to be 60.7 million tons of feces and 27.7 million tons of urine (Table 2.13.2). Livestock waste in Japan contains 670 thousand tons of nitrogen and 108 thousand tons of phosphorus. Those amounts are very large considering that the amounts of nitrogen and phosphorus used as chemical fertilizer in Japan are 480 thousand tons and 250 thousand tons, respectively. Statistics for the total amount of slaughterhouse residue are not available, but the quantity (about 1.5 million tons) is less than 2% of the total amount of animal waste.

2.13.2 General treatment and usage of animal waste

Dr. Haga (National Agriculture and Food Research Organization) summarized the main systems used for treatment of major livestock waste in Japan (Fig. 2.13.1). According to the results of an investigation by the Agricultural Production Bureau of the Livestock Industry Department, solid parts of manure were just piled or operated by a simple composting process and liquid parts of manure were stored and used on their own fields as fertilizer in most dairy cattle and beef cattle farms. In the case of pig breeding, composting with a forced aeration system was the main method used for processing of solid parts and wastewater purification systems were used on most farms for treatment of liquid parts. Moreover, after drying treatment, layer and broiler manure is sold and used in other farms in many cases. Generally, dairy and beef cattle farmers have their own land for cultivation but pig and poultry farmers do not. This is thought to be the major reason for the differences in livestock waste treatments. The slaughterhouse residue and other by-products of meat processing are treated by a process called “rendering”, and most of them are used as edible fat and oil, feed, or an industrial source.

2.13.3 Animal waste value and total amount in the world

To calculating the value of livestock waste as resources, consideration should be given to its value as 1) a source of plant nutrition (nitrogen, phosphorus, etc.), 2) a source of organic compounds with favorable effects on crop growth and 3) a source of energy. Because of the differences in breeding conditions, it is difficult to accurately calculate the amount of nutrients such as nitrogen and phosphorus in manure of all livestock throughout the world. Based on FAO statistics, total amount of nutrients in manure of all livestock in the world is estimated to be about 140-150 times greater than those in Japan.