WASTES IN RELATION TO AGRICULTURE AND FORESTRY 



41 



it contains would cost more than six times as 

 much as was expended for commercial fertilizers 

 in 1936. Its organic matter content is double 

 the amount of soil humus annually destroyed in 

 growing the Nation's grain and cotton crops. 



How times do change ! 



In 1966, animal excrement was considered by 

 some to be the bete noire of agricultural wastes. 

 Waste production by our domestic animals is 

 equivalent to that of a human population of 1.9 

 billion. Sewage treatment facilities for this live- 

 stock are infinitesimal. 



The change in view towards manure has oc- 

 curred because livestock and poultry production 

 in the United States is becoming concentrated in 

 large scale, confinement-type enterprises. These in- 

 clude multihundred-cow dairy operations, multi- 

 thousand-head beef or hog f eedlots, and enterprises 

 with many hundreds of thousands of birds. Such 

 large concentrations of animals or birds have 

 greatly magnified the problems of handling wastes, 

 including health hazards and esthetic nuisances. 

 Economic studies indicate that the costs of han- 

 dling manures make them no longer competitive in 

 price with chemical fertilizers. Table 1 provides 

 an indication of the amount of solid wastes pro- 

 duced by livestock in the United States. Domestic 

 animals produce over a billion tons of fecal wastes 

 a year. Liquid effluent amounts to over 400 million 

 tons. Used bedding, paunch manure from ab- 

 batoirs, and dead carcasses make the total annual 

 production of animal wastes close to 2 billion tons. 



Possibly half of this waste is produced under 

 concentrated conditions. Cattle in a feedlot for 

 fattening, or dairy cows maintained for high milk 



Table 1. — Production oj wastes by livestock in the 

 United States 





U.S. 





Total pro- 





Total pro- 



Livestock 



popu- 



Solid 



duction of 



Liquid 



duction of 





lation 



wastes ' 



solid waste 



wastes 



liquid 





1965 









wastes 



Cattle 



Horses - 



Hogs 



Sheep 



Chickens. . 



Turkeys 



Ducks 



Total. __ 



Mil- 

 lions 



107 



3 



53 



26 



375 



104 



11 



G.lcap./ 

 day 



23, 600 



16, 100 



2, 700 



1, 130 



182 



448 



336 



Million 



tons i/r. 



1, 004. 

 17.5 

 57.3 

 11.8 

 27.4 

 19.0 

 1.6 



1, 138.6 



e./cop./ 



day 



9, 000 



3,600 



1,600 



680 



Milium 

 Inns i/r. 



390. 



4.4 



33.9 



7. 1 



435.4 



production, may produce double the daily amount 

 of wastes shown in the table. 



Table 2 shows the population equivalent of the 

 fecal production by various kinds of livestock in 

 terms of biochemical oxygen demand (BOD) . For 

 example, a feedlot carrying 10,000 head of cattle 

 has about the same sewage disposal problem as a 

 city of 164,000 people. The city will be using 8,200,- 

 000 gallons of water a day to carry off the sewage. 

 Such amounts of w 7 ater are never used and are 

 seldom even available at the feedlot. 



BOD is an important measurement in determin- 

 ing the quality of water. BOD indicates the amount 

 of oxygen required for the oxidation of the organic 

 matter present in a sample of water. It is ex- 

 pressed by the amount of oxygen the water will 

 absorb when it is incubated for a 5-day period at 

 68° F. 



In such tests, water absorbing not more than 1 

 p.p.m. of oxygen in 5 days can generally be con- 

 sidered very pure; 3 p.p.m. suggests fairly clean 

 water; but water absorbing 5 p.p.m. or more of 

 oxygen is of doubtful purity. 



BOD demand of a waste acts to deplete dis- 

 solved oxygen in water. Fish depend upon this 

 dissolved oxygen in order to breathe. Most fish 

 should have 5 p.p.m. of dissolved oxygen — brook 

 trout should have 6 p.p.m. or more. However, a 

 sluggish stream during the summer may have its 

 dissolved oxygen lowered to 1 to 3 p.p.m. 



A primary problem in handling animal waste 

 involves coping with its high BOD. A sample of 

 concentrated liquid waste from a pigpen has been 

 reported as having a BOD as high as ,*>0,000. This 

 undoubtedly is an unusually high value. 



Untreated municipal sewage has a BOD of about 

 100 to 400 p.p.m. This moans that such sewage 

 entering a stream already low in dissolved oxygen 



Table 2. — Population equivalent of the heal pro- 

 duction by animals, in term* of biochemical 

 oxygen demand (BOD) 



Biotype 



ve Population 



BOD per equivalent 

 unit of waste 



1 Geldreich and others (47). 



2 Horses and mules on farms as work stock. 



:'.lday Lb. 



M:\n 150 1.0 1.0 



Horse 16,100 0.105 L1.3 



Cow 23,600 .103 16.4 



Sheep 1,130 .325 2.45 



Bog -.700 .103 1.90 



Ben is- .115 ll 



