Farm animal wastes manures

Waste heat from farming, animal manure, crop production, and municipal solid residues could also be used for power generation. 

The U.S. Department of Agriculture s 1938 Yearbook of Agriculture contains these statements One billion tons of manure, the annual product of livestock on American farms, is capable of producing 3,000,000,000 worth of increase in crops. The potential value of this agricultural resource is three times that of the nation s wheat crop and equivalent to 440 for each of the country s 6,800,000 farm operators. Since then, animal wastes have been transformed from a definite asset to a liability. By 1965, the disposal of animal excreta had become a serious problem (American Chemical Society, 1969). At any given time, an estimated 11 million cattle were on feedlots, the capacities of which ranged from 1000 to 50,000 head. 

In livestock farming, where all manures and wastes are returned to the soil, and the only product removed is the animals, it is obvious that the maintenance of fertility is a comparatively simple matter. In contrast, in grain farming most of the product is removed as grain and sold on the market. Any direct comparison between the two systems is unfair and may be misleading. The nutrients removed in harvested crops must necessarily be returned in part as fertilizers, if the fertility of the soil on such areas is to be kept at the same level as where livestock is the only marketed product. 

Agricultural waste. To prevent overregulation of farms and promote waste recycling, solid wastes generated by crop or animal farming are excluded from the definition of hazardous waste provided that the wastes are returned to the ground as fertilizers or soil conditioners. Examples of such wastes are crop residues and manures. 

Since 1984 there is a political and social discussion about the surplus of organic/animal manure and the air pollution, special the acid rain. It are the minerals in the farm waste and the NH3 in the ventilation air, which are in discussion. 

Examples of sites with the characteristics mentioned above and, thus, potential reservoirs of antibiotic resistance are common in areas subjected to human activities (Fig. 2). Particularly, sites in which the use or disposal of antimicrobials is frequent, such as animal farms or municipal waste water treatment plants, are likely habitats to favour the spreading of antibiotic resistance. In Europe, the use of antibiotics as growing factors in animal husbandry is prohibited since 2006 [47]. However, animal farming still represents a critical point for antibiotic resistance development and dissemination. Among the major main routes of dispersal are manure, which sometimes is used directly or after composting in agriculture as fertilizers [48, 49], and animal farms waste water [50-53]. 

Soil amendment with animal manures is a common practice for either increasing SOM and nutrient content or disposing of wastes from intensive animal farms. However, the application of organic amendments that are not sufficiently mature and stable may adversely affect soil properties, especially the content and quality of SOM pools. 

---