2.3.3. Horse manure

Approximately 75% of horse farms utilize or store horse manure (HM) on-site as grasslands and this is the primary means of disposal [36]. Equine waste produces odors and could contaminate water natural sources via runoff during storage or after land application [37, 38]. Due to the importance of storing waste for potential use in agricultural production systems, an increasing cost is tolerated by the farmer to handle this material for potential use [39]. The disposal of HM (Figure 3C) in some Germany regions became increasingly difficult for the owners during the last years due to the lack of arable land and its low fertilizer quality. Additionally, equitation becomes more and more popular in urban areas. This leads to an increase in horse barns and an excess of HM in these regions, which causes a sharp rise in manure removal costs. The composition of HM is dependent on the bedding material and the frequency of stall cleaning. HM is a good source of nitrogen because of its suitable C/N ration that can be also explored for the digestion of nitrogen rich organic waste such as liquid pig manure and poultry manure [40].

Figure 4 shows some of the crops grown with organic fertilizers. Peppers grown in sewage sludge amended soil (Figure 4A), peppers grown in chicken manure amended soil (Figure 4B), eggplants grown in horse manure amended soil (Figure 4C), kale and collards grown in yard waste amended soil (Figure 4D). The increase in crop yield due to incorporation of organic amendments in agricultural production systems reduces the need of synthetic inorganic fertilizers.

2.4. Antibiotics in animal manure

The American Association of Concerned Scientists reported that 11.2–12.8 million kg of antibacterial compounds were used for on-farm animals for medicinal purposes [41] in 1 year alone. Because pharmaceuticals (Figure 5) do not metabolize completely in the animal body, they excrete with urine and feces either in their native form or in the form of metabolites [42]. Increased fertilization of farmland with organic fertilizers such as municipal SS, CM, HM and cow manures contribute to the introduction of antibiotics into soil used for growing plants, surface water (through runoff), groundwater (through leaching), and into edible plants or other living organisms through bioaccumulation. These pharmaceuticals can generate a number of negative consequences. Pharmaceuticals in agricultural production systems are one of the emerging contaminants [43]. Among all groups of veterinary pharmaceuticals, antibiotics exert significant influence on soil microorganisms that recycle waste. Once introduced to the soil, they might affect the structure and function of bacterial communities and the development and spread of antibiotic resistance. Numerous studies have documented changes of soil microbial community structure due to exposure to antibiotics in the environment [44]. According to Masse et al. [45], the most persistent groups of pharmaceuticals are tetracyclines (TCS, T1/2 > 100 days). The presence and persistence of chlortetracycline, tetracycline, oxytetracycline, and other members of the TCs in animal manures used as organic soil amendment might remain in soils for many years [45, 46], due to their strong sorption to the soil particles. There is a lack of information on the behavior of pharmaceuticals and veterinary medicine in soils and fertilizers used in agricultural production and their potential risk to human health [47].

Figure 4. Crops grown with animal manure: (peppers (A) grown with sewage sludge; peppers grown with chicken manure (B); eggplants grown with horse manure (C); kale and collards grown in yard waste compost (D) under field condition at Kentucky State University HR Benson Research and Demonstration Farm (Franklin County, Kentucky, USA).

Biochar and Animal Manure Impact on Soil, Crop Yield and Quality

http://dx.doi.org/10.5772/intechopen.77008

51

Figure 3. Yard waste compost (A), vermicompost (B), and horse manure (C) organic fertilizers.

Biochar and Animal Manure Impact on Soil, Crop Yield and Quality http://dx.doi.org/10.5772/intechopen.77008 51

Figure 4. Crops grown with animal manure: (peppers (A) grown with sewage sludge; peppers grown with chicken manure (B); eggplants grown with horse manure (C); kale and collards grown in yard waste compost (D) under field condition at Kentucky State University HR Benson Research and Demonstration Farm (Franklin County, Kentucky, USA).

#### 2.4. Antibiotics in animal manure

dung and biogas plant slurry can be used as a raw material in vermicomposting. The NPK elements and C/N ratio of vermicompost revealed its agronomic value as organic soil conditioner. Accordingly, many investigators reported that vermicompost has important properties that can be explored as a new technology for converting organic wastes into a product rich in

Approximately 75% of horse farms utilize or store horse manure (HM) on-site as grasslands and this is the primary means of disposal [36]. Equine waste produces odors and could contaminate water natural sources via runoff during storage or after land application [37, 38]. Due to the importance of storing waste for potential use in agricultural production systems, an increasing cost is tolerated by the farmer to handle this material for potential use [39]. The disposal of HM (Figure 3C) in some Germany regions became increasingly difficult for the owners during the last years due to the lack of arable land and its low fertilizer quality. Additionally, equitation becomes more and more popular in urban areas. This leads to an increase in horse barns and an excess of HM in these regions, which causes a sharp rise in manure removal costs. The composition of HM is dependent on the bedding material and the frequency of stall cleaning. HM is a good source of nitrogen because of its suitable C/N ration that can be also explored for the digestion of nitrogen rich organic waste such as liquid pig

Figure 4 shows some of the crops grown with organic fertilizers. Peppers grown in sewage sludge amended soil (Figure 4A), peppers grown in chicken manure amended soil (Figure 4B), eggplants grown in horse manure amended soil (Figure 4C), kale and collards grown in yard waste amended soil (Figure 4D). The increase in crop yield due to incorporation of organic amendments in agricultural production systems reduces the need of synthetic

Figure 3. Yard waste compost (A), vermicompost (B), and horse manure (C) organic fertilizers.

plant nutrients [35].

50 Agricultural Waste and Residues

2.3.3. Horse manure

manure and poultry manure [40].

inorganic fertilizers.

The American Association of Concerned Scientists reported that 11.2–12.8 million kg of antibacterial compounds were used for on-farm animals for medicinal purposes [41] in 1 year alone. Because pharmaceuticals (Figure 5) do not metabolize completely in the animal body, they excrete with urine and feces either in their native form or in the form of metabolites [42]. Increased fertilization of farmland with organic fertilizers such as municipal SS, CM, HM and cow manures contribute to the introduction of antibiotics into soil used for growing plants, surface water (through runoff), groundwater (through leaching), and into edible plants or other living organisms through bioaccumulation. These pharmaceuticals can generate a number of negative consequences. Pharmaceuticals in agricultural production systems are one of the emerging contaminants [43]. Among all groups of veterinary pharmaceuticals, antibiotics exert significant influence on soil microorganisms that recycle waste. Once introduced to the soil, they might affect the structure and function of bacterial communities and the development and spread of antibiotic resistance. Numerous studies have documented changes of soil microbial community structure due to exposure to antibiotics in the environment [44]. According to Masse et al. [45], the most persistent groups of pharmaceuticals are tetracyclines (TCS, T1/2 > 100 days). The presence and persistence of chlortetracycline, tetracycline, oxytetracycline, and other members of the TCs in animal manures used as organic soil amendment might remain in soils for many years [45, 46], due to their strong sorption to the soil particles. There is a lack of information on the behavior of pharmaceuticals and veterinary medicine in soils and fertilizers used in agricultural production and their potential risk to human health [47].

2.6. Application of biochar in agricultural production

soil chemical properties [53].

ment [53].

Currently little information exists in the literature if biochar addition to soil as organic amendment can reduce the plant uptake of trace-elements and reduce toxic metals bioavailability to edible plants. Such practice, if found effective, can assist in management of contaminated agricultural and urban soils from current and past use of municipal SS and might be also useful in mining reclamation. Acidification can affect both the soil biota and biogeochemical processes, thus decreasing agricultural production [52, 53]. Biochar has been reported to modify soil quality characteristics, thereby increasing crop yields [54]. Because it is usually alkaline in nature, biochar can increase the pH of acidic soils [55, 56]. Furthermore, biochar application has also been promoted as a means of contributing to the mitigation of climate change by reducing soil N2O emissions [53, 57, 58]. Biochar addition changed soil chemical properties, including increasing soil pH, total nitrogen (TN), total carbon (TC), C/N ratio, and cation-exchange capacity (CEC), and shifted the bacterial community composition. As biochar has been considered unlikely to be used by soil microbes [59], and it cannot directly impact soil microbial community. Therefore, biochar may affect soil microbial community via improving

Biochar and Animal Manure Impact on Soil, Crop Yield and Quality

http://dx.doi.org/10.5772/intechopen.77008

53

When used in acidified soil amelioration, biochar can increase crop yield through improving soil chemical conditions and changing the availability of nutrients. It can also impact soil microbial community by increasing diversity of soil microbes and changing relative abundances of their taxa) via changing soil chemical properties, thus influencing soil nutrient (e.g., C, N) cycling and controlling greenhouse gas emissions. By contrast, biochar can also enhance soil N losses to the atmosphere by stimulating both nitrification and denitrification, thus decreasing the efficiency of N-fertilizer utilization. Therefore, the effect of biochar on the efficiency of N fertilizer should be considered when it is widely recommended as soil amend-

Gómez-Muñoz et al. [60] reported that, when diverse types of urban waste (human urine, sewage sludge, composted household waste) and agricultural wastes (cattle slurry, farmyard manure and deep litter) applied annually for 11 years (at normal and accelerated rates), soil water retention and total carbon improved. Cattle manure, sewage sludge and composted household waste increased soil total N by 13–131% compared to the mineral fertilizer (NPK). The interaction of biochar and compost used in agricultural practices affect each other's properties. Biochar could change the physicochemical properties, microorganisms, degradation, mummification and gas emission of composting, such as the increase of nutrients, cation exchange capacity (CEC), organic matter and microbial activities. Composting and addition of animal manure to biochar could change the characteristic properties of biochar such as its surface polar and non-polar attractions sites, ion-exchange sites, and electrostatic attraction functional groups (Figure 6), such as the improvement of nutrients availability, CEC, functional groups on biochar surface and soil organic matter (OM). These changes would poten-

2.7. Animal manure and agricultural waste application: An overview

tially improve the efficiency of the biochar and remediation of pollution [61].

Figure 5. Pharmaceuticals used in animal feeding operations to protect against bacterial and disease infection.

#### 2.5. Trace metals in animal manure

Animal manure is a source of valuable plant nutrients, but also a source of air and soil pollution and a threat to aquifers and surface waters unless managed carefully to minimize nutrient loss [48]. In addition, animal manures such as municipal SS is a source of trace metals [49] that might accumulate in edible plants when SS is used as an organic fertilizer and might also contaminate our natural water resources with trace metals. To avoid direct leakage to water abstraction plants or groundwater, manure must not be applied 50 feet (15 m) from potable water wells and 200 feet (60 m) uphill of conduits to groundwater. Furthermore, special care must be taken when applying manure to fields with high leaching potential or within 1000 feet (305 m) of municipal wells [50].

Studies carried out by Gondek et al. [51] revealed that composting of organic materials has a significant effect on changes in mobile forms of heavy metals. The authors found that biochar and municipal SS added to maize straw immobilized Cd and Pb soluble forms due to addition of biochar, whereas maize straw and SS alone did not impact cd and Pb mobility.
