3. Experimental studies conducted at the University of Kentucky South Farm (Fayette County, Kentucky)

#### 3.1. Impact of animal manure on tomato yield

Tomato (Solanum lycopersicum var. Mountain Spring) seedlings of 52 days old were planted in raised, plastic-mulched, freshly tilled soil at 18 inch in-row spacing. The entire study area contained 30 plots (3 replicates 10 treatments). Each treatment was replicated three times in a randomized complete block design (RCBD) with the following treatments: (1) control (NM no-mulch untreated soil); (2) sewage sludge (SS); (3) horse manure (HM); (4) chicken manure (CM); and (5) yard waste compost (YWC). Each of the five treatments was also mixed with 1% (w/w) biochar obtained from Wakefield Agricultural Carbon (Columbia, MO) to make a total of 10 treatments. The soil in six plots was mixed with SS obtained from the Metropolitan Sewer District, Louisville, KY at 5% N on dry weight basis [62, 63]. Six plots were mixed with CM obtained from the Department of Animal and Food Sciences, University of Kentucky, Lexington, Kentucky at 5% N on dry weight basis. The soil in six plots was mixed with HM obtained from the Kentucky horse park, College of Agriculture, University of Kentucky, Lexington, Kentucky at 5% N. The soil in six plots was mixed with YWC at 5% N and the native soils in six plots was used as a no-mulch (NM) control treatment (roto-tilled bare soil) for comparison purposes. Biochar was mixed in three plots in each of the soil amendments, while other three plots in each soil amendment were left without biochar for comparison purposes. Soil amendments were added to native topsoil, mixed, and rototilled to a depth of 15 cm of top soil. The plots were hand transplanted with tomato and irrigated by a uniform drip irrigation system. Fruits were harvested three times during the growing season on August 3, August 19, and September 8, 2016. At each harvest, fruits were collected, weighed and counted. Data were statistically analyzed using ANOVA and the means were compared using Duncan's multiple range test [64].

### 3.1.1. Research findings

3. Experimental studies conducted at the University of Kentucky

Tomato (Solanum lycopersicum var. Mountain Spring) seedlings of 52 days old were planted in raised, plastic-mulched, freshly tilled soil at 18 inch in-row spacing. The entire study area contained 30 plots (3 replicates 10 treatments). Each treatment was replicated three times in a randomized complete block design (RCBD) with the following treatments: (1) control (NM no-mulch untreated soil); (2) sewage sludge (SS); (3) horse manure (HM); (4) chicken manure (CM); and (5) yard waste compost (YWC). Each of the five treatments was also mixed with 1% (w/w) biochar obtained from Wakefield Agricultural Carbon (Columbia, MO) to make a total of 10 treatments. The soil in six plots was mixed with SS obtained from the Metropolitan Sewer District, Louisville, KY at 5% N on dry weight basis [62, 63]. Six plots were mixed with CM obtained from the Department of Animal and Food Sciences, University of Kentucky, Lexington, Kentucky at 5% N on dry weight basis. The soil in six plots was mixed with HM obtained from the Kentucky horse park, College of Agriculture, University of Kentucky, Lexington, Kentucky at 5% N. The soil in six plots was mixed with YWC at 5% N and the native soils in six plots was used as a no-mulch (NM) control treatment (roto-tilled bare soil) for comparison purposes. Biochar was mixed in three plots in each of the soil amendments, while other three plots in each soil amendment were left without biochar for comparison purposes. Soil amendments were added to native topsoil, mixed, and rototilled to a depth of 15 cm of top soil. The plots were hand transplanted with tomato and irrigated by a uniform drip irrigation system. Fruits were harvested three times during the growing season on August 3, August 19, and September 8, 2016. At each harvest, fruits were collected, weighed and counted. Data were statistically analyzed using ANOVA and the means were compared using Duncan's multiple

Figure 6. Schematic diagram of biochar showing its electrostatic attraction sites, ion-exchange sites, polar and non-polar

South Farm (Fayette County, Kentucky)

attraction sites collectively known as surface functional groups.

54 Agricultural Waste and Residues

3.1. Impact of animal manure on tomato yield

range test [64].

Plants grown in soil fertilized with CM had 8.2, 15.8, and 1.3 kg fruits/3 plants in harvest 1, harvest 2, and harvest 3, respectively (Table 1). Whereas, biochar added to CM, HM, and NM native soil did not alter tomato yield in harvest 1 (P > 0.05). Accordingly, the synergistic effects of biochar mixed with soil amendments used in this study was not observed after biochar addition in harvest 1. This could be due to the low amount of biochar (1% w/w) used in each treatment. Results of harvest 1 also revealed that the addition of biochar to SS and YW treatments significantly increased fruit yield from 5.2 kg and 3.9 to 6.3 and 5.7 kg/3 plants, respectively, indicating a positive effect of biochar on the growth and yield of tomato grown in SS and YW treatments. In harvest 2, plots fertilized with HM mixed with biochar revealed a significant increase (P < 0.05) in tomato yield. Whereas, biochar added to other soil treatments did not promote tomato yield (Table 1). In harvest 3, the synergistic effect of biochar was observed in HM and NM native soil (Table 1). However, total weight of tomato fruits collected after three harvests presented in Figure 7 revealed that HM and YW amended with biochar significantly (P < 0.05) increased tomato yield compared to other treatments indicating a positive effect on the growth and yield of tomato.

Overall tomato three harvests, the synergistic effects of biochar was only observed in HM and YW amended soils (Figure 7). Total marketable tomato yield of biochar amended soils was increased by 63 and 20% in HM and YW treatments, respectively compared to other soil treatments. Regardless of soil treatments, it could be concluded that harvest 2 had the greatest yield and greatest number of fruits compared to the other two harvests (Figure 8).


Statistical comparisons were carried out among soil management practices using SAS procedure. Each value is an average of three replicates std. error.

Table 1. Average weights of tomato fruits collected at three harvests from plants grown under 10 soil management practices at the University of Kentucky South Farm (Fayette County, Kentucky, USA).

(12.4 Mg ha<sup>1</sup>

) over four seasons. Most importantly, surface soil pH, P, Ca, and Mg were

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significantly enhanced by CM addition. Antonious et al. [63] also reported that CM enhanced yield and quality of field-grown kale and collard greens. CM is preferred among other animal wastes because of its high concentration of macro-nutrients [66]. Poultry litter is poultry manure mixed with the bedding (wood shavings, rice hulls, etc.) that is scooped up when the houses are cleaned. Chicken litter nutrient composition depends on the technique used for clean-out the house, methods of litter storage, and many other factors, such as storage house air conditions. An average nutrient percentage content of 3-3-2 means that an average ton of poultry litter contains 60 pounds of nitrogen, 60 pounds of phosphate (P2O5) and 40 pounds of potash (K2O) per ton of litter. Poultry litter may contain nearly small amounts of essential elements needed for plant growth and composition. Such as sulfur, but the amounts are usually small. Due to the increased prices of inorganic fertilizers, farmers interest in using

Due to the consumer demand of chicken meat, chicken manure from chicken condensed feeding operations has become available in increasing quantities for utilization in agricultural production systems as organic fertilizer. While the use of organic wastes has been in practice for centuries world-wide and in the recent times, there still exists a need to assess the potential impacts of CM on soil chemical properties and crop yield and in particular evaluating the critical application levels. Moreover, the need and utilization of CM has overtaken the use of other animal manure (e.g., pig manure, horse manure, and cow manure) because of its high content of N, P, and K [67]. Escalating prices of inorganic fertilizers due to the increase in the fuel prices has also prompted the use of CM and other animal manure. Accordingly, knowledge about the environmental problems and adoption of appropriate solutions and practices to enhance and protect soil quality require timely delivery of research

Fruits and vegetables contain various vitamins and nutrients important for human health. Discovery of phytochemicals with antioxidant properties and their health promoting benefit have paved the way to a food revolution and promising for an age of food with nutritional composition and good health [68]. Tomato (Solanum lycopersicum), among antioxidant-rich commodities, has achieved a spectacular status because of its rich composition and widespread consumption. It is one of the major vegetable crops, grown in almost every country of the world. Studies indicated that regular intake of cooked tomato as a part of the vegetable regime appears to be the major nutritional factor accounting for lower risk of prostate cancer, digestive tract cancer and coronary heart diseases in the Mediterranean region. In tomato fruits and most vegetables, ascorbic acid (vitamin C) and phenols that have antioxidant properties protect animals and humans from various diseases. Lycopene, constituting 80–90% of the total carotenoid content present in tomatoes and tomato products, has been believed to contribute to the reduced risks of some types of cancers. Vitamin C (ascorbic acid) in tomato fruits provides about 40% of the required dietary allowance for human health. As a result, enhancing the levels of these healthy chemicals in tomato fruits may form an efficient way to improve

poultry litter as organic fertilizer has also risen sharply.

3.2. Impact of animal manure on tomato fruit nutritional composition

and educational technology.

Figure 7. Total weights of tomato fruits collected from three harvests of tomato plants grown under 10 soil management practices. Statistical comparisons were carried out among soil treatments using SAS procedure. Values accompanied by the same letter(s) are not significantly (P > 0.05) different. Each value is an average of three replicates std. error.

Figure 8. Overall tomato fruit harvests of three plants grown at the university of Kentucky south farm, regardless of soil treatments. Statistical comparisons were carried out among three harvests using SAS procedure. Values accompanied by the same letter(s) are not significantly (P > 0.05) different. Each value is an average of 10 treatments std. error.

The use of organic wastes is also being encouraged for by different environmental organizations world-wide to preserve the sustainability of agricultural systems [65]. These two authors conducted a greenhouse experiment to assess the effect of CM on soil chemical properties and yield of spinach. They concluded that CM is a potential source of plant nutrients. Their study provided insights to critical threshold values in response to the optimum yield in spinach and uptake of N and P on leaves particularly at high CM application rate. The results indicated an increase in spinach yield as measured in dry matter content. In addition, the use of 15 different amendment combinations that contain equal amounts of carbon (C), were applied through CM compost, charcoal, and forest litter during four cropping cycles with rice and sorghum. The authors reported that CM amendments resulted in the highest (P < 0.05) cumulative crop yield (12.4 Mg ha<sup>1</sup> ) over four seasons. Most importantly, surface soil pH, P, Ca, and Mg were significantly enhanced by CM addition. Antonious et al. [63] also reported that CM enhanced yield and quality of field-grown kale and collard greens. CM is preferred among other animal wastes because of its high concentration of macro-nutrients [66]. Poultry litter is poultry manure mixed with the bedding (wood shavings, rice hulls, etc.) that is scooped up when the houses are cleaned. Chicken litter nutrient composition depends on the technique used for clean-out the house, methods of litter storage, and many other factors, such as storage house air conditions. An average nutrient percentage content of 3-3-2 means that an average ton of poultry litter contains 60 pounds of nitrogen, 60 pounds of phosphate (P2O5) and 40 pounds of potash (K2O) per ton of litter. Poultry litter may contain nearly small amounts of essential elements needed for plant growth and composition. Such as sulfur, but the amounts are usually small. Due to the increased prices of inorganic fertilizers, farmers interest in using poultry litter as organic fertilizer has also risen sharply.

Due to the consumer demand of chicken meat, chicken manure from chicken condensed feeding operations has become available in increasing quantities for utilization in agricultural production systems as organic fertilizer. While the use of organic wastes has been in practice for centuries world-wide and in the recent times, there still exists a need to assess the potential impacts of CM on soil chemical properties and crop yield and in particular evaluating the critical application levels. Moreover, the need and utilization of CM has overtaken the use of other animal manure (e.g., pig manure, horse manure, and cow manure) because of its high content of N, P, and K [67]. Escalating prices of inorganic fertilizers due to the increase in the fuel prices has also prompted the use of CM and other animal manure. Accordingly, knowledge about the environmental problems and adoption of appropriate solutions and practices to enhance and protect soil quality require timely delivery of research and educational technology.

#### 3.2. Impact of animal manure on tomato fruit nutritional composition

The use of organic wastes is also being encouraged for by different environmental organizations world-wide to preserve the sustainability of agricultural systems [65]. These two authors conducted a greenhouse experiment to assess the effect of CM on soil chemical properties and yield of spinach. They concluded that CM is a potential source of plant nutrients. Their study provided insights to critical threshold values in response to the optimum yield in spinach and uptake of N and P on leaves particularly at high CM application rate. The results indicated an increase in spinach yield as measured in dry matter content. In addition, the use of 15 different amendment combinations that contain equal amounts of carbon (C), were applied through CM compost, charcoal, and forest litter during four cropping cycles with rice and sorghum. The authors reported that CM amendments resulted in the highest (P < 0.05) cumulative crop yield

Figure 8. Overall tomato fruit harvests of three plants grown at the university of Kentucky south farm, regardless of soil treatments. Statistical comparisons were carried out among three harvests using SAS procedure. Values accompanied by the same letter(s) are not significantly (P > 0.05) different. Each value is an average of 10 treatments std. error.

Figure 7. Total weights of tomato fruits collected from three harvests of tomato plants grown under 10 soil management practices. Statistical comparisons were carried out among soil treatments using SAS procedure. Values accompanied by the same letter(s) are not significantly (P > 0.05) different. Each value is an average of three replicates std. error.

56 Agricultural Waste and Residues

Fruits and vegetables contain various vitamins and nutrients important for human health. Discovery of phytochemicals with antioxidant properties and their health promoting benefit have paved the way to a food revolution and promising for an age of food with nutritional composition and good health [68]. Tomato (Solanum lycopersicum), among antioxidant-rich commodities, has achieved a spectacular status because of its rich composition and widespread consumption. It is one of the major vegetable crops, grown in almost every country of the world. Studies indicated that regular intake of cooked tomato as a part of the vegetable regime appears to be the major nutritional factor accounting for lower risk of prostate cancer, digestive tract cancer and coronary heart diseases in the Mediterranean region. In tomato fruits and most vegetables, ascorbic acid (vitamin C) and phenols that have antioxidant properties protect animals and humans from various diseases. Lycopene, constituting 80–90% of the total carotenoid content present in tomatoes and tomato products, has been believed to contribute to the reduced risks of some types of cancers. Vitamin C (ascorbic acid) in tomato fruits provides about 40% of the required dietary allowance for human health. As a result, enhancing the levels of these healthy chemicals in tomato fruits may form an efficient way to improve human health conditions. In response to this opportunity, numerous investigations have been conducted to identify the factors influencing the contents of lycopene and vitamin C in tomatoes. The results demonstrated consistent differences in lycopene and vitamin C content between tomato cultivars, which can be magnified by agricultural management. A relationship has been established associating electrical conductivity (EC) and light intensity with lycopene and vitamin C content in tomato fruits. Generally, moderate EC growing conditions enhance tomato health quality; solar radiation is favorable to lycopene and vitamin C accumulation, whereas strongly intense light exposure inhibits lycopene synthesis. Temperatures beyond the optimum temperature range may inhibit lycopene biosynthesis. However, the effects of temperature on vitamin C content are not always conclusive. The effects of nutrients (N, P, K, and Ca) and water availability have also been reviewed, but results are sometimes contradictory. Up-to-date studies dealing with soil amendments and vitamin C, phenols, and sugars contents in tomato fruits are reviewed in this chapter. Previous studies indicated that increasing both P and N application (up to 140 kg P ha–<sup>1</sup> and 150 kg N ha–<sup>1</sup> , respectively) significantly increased the vitamin C content of tomato fruits [10]. Concentrations of vitamin C varied significantly among plant species and among plants grown under different animal manures. Ascorbic acid in tomato fruits (Figure 9) was greatest in plants grown in CM amended soils compared to NM un-amended soil.

Tomatoes also contain moderate amounts of water-soluble phenolic, flavonoids (quercetin, kaempferol and naringenin) and the hydrocinnamic acids (caffeic, chlorogenic, ferulic and pcoumaric acids), mainly concentrated in skin [69, 70]. Polyphenols are secondary metabolites of plants that contain in their structure the aromatic ring with one or more phenolic groups. Such molecules have great antioxidant potential. The phenolics of tomatoes are found to occur in the skin. Total phenols in tomato fruits of plants grown in amended soils were significantly (P < 0.05) greater compared to NM un-amended soil (Figure 10). Concentration levels of soluble sugars in tomato fruits (Figure 11) revealed also that YW compost provided the

Figure 10. Concentrations of total phenols in tomato fruits of plants grown under different soil management practices. Statistical comparisons were carried out among soil treatments using SAS procedure. Values accompanied by the same

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However, one can ask whether the higher content of vitamin C, phenols, and soluble sugars in plants grown in animal manure treatments is due to higher synthesis of these water soluble compounds by plants grown in organic manure, or due to increased absorption from soil by the plants roots, or these compounds were found in the plants due to their presence in native

Figure 11. Concentrations of soluble sugars in tomato fruits of plants grown under different soil management practices. Statistical comparisons were carried out among soil treatments using SAS procedure. Values accompanied by the same

letter(s) are not significantly (P > 0.05) different. Each value is an average of three replicates std. error.

highest concentrations of total phenols among the other amendments tested.

letter(s) are not significantly (P > 0.05) different. Each value is an average of three replicates std. error.

Figure 9. Concentrations of ascorbic acid (vitamin C) in tomato fruits of plants grown under different soil management practices. Statistical comparisons were carried out among soil treatments using SAS procedure. Values accompanied by the same letter(s) are not significantly (P > 0.05) different. Each value is an average of three replicates std. error.

human health conditions. In response to this opportunity, numerous investigations have been conducted to identify the factors influencing the contents of lycopene and vitamin C in tomatoes. The results demonstrated consistent differences in lycopene and vitamin C content between tomato cultivars, which can be magnified by agricultural management. A relationship has been established associating electrical conductivity (EC) and light intensity with lycopene and vitamin C content in tomato fruits. Generally, moderate EC growing conditions enhance tomato health quality; solar radiation is favorable to lycopene and vitamin C accumulation, whereas strongly intense light exposure inhibits lycopene synthesis. Temperatures beyond the optimum temperature range may inhibit lycopene biosynthesis. However, the effects of temperature on vitamin C content are not always conclusive. The effects of nutrients (N, P, K, and Ca) and water availability have also been reviewed, but results are sometimes contradictory. Up-to-date studies dealing with soil amendments and vitamin C, phenols, and sugars contents in tomato fruits are reviewed in this chapter. Previous studies indicated that increasing both P

the vitamin C content of tomato fruits [10]. Concentrations of vitamin C varied significantly among plant species and among plants grown under different animal manures. Ascorbic acid in tomato fruits (Figure 9) was greatest in plants grown in CM amended soils compared to NM

Tomatoes also contain moderate amounts of water-soluble phenolic, flavonoids (quercetin, kaempferol and naringenin) and the hydrocinnamic acids (caffeic, chlorogenic, ferulic and pcoumaric acids), mainly concentrated in skin [69, 70]. Polyphenols are secondary metabolites of plants that contain in their structure the aromatic ring with one or more phenolic groups. Such molecules have great antioxidant potential. The phenolics of tomatoes are found to occur in the skin. Total phenols in tomato fruits of plants grown in amended soils were significantly

Figure 9. Concentrations of ascorbic acid (vitamin C) in tomato fruits of plants grown under different soil management practices. Statistical comparisons were carried out among soil treatments using SAS procedure. Values accompanied by the same letter(s) are not significantly (P > 0.05) different. Each value is an average of three replicates std. error.

, respectively) significantly increased

and N application (up to 140 kg P ha–<sup>1</sup> and 150 kg N ha–<sup>1</sup>

un-amended soil.

58 Agricultural Waste and Residues

Figure 10. Concentrations of total phenols in tomato fruits of plants grown under different soil management practices. Statistical comparisons were carried out among soil treatments using SAS procedure. Values accompanied by the same letter(s) are not significantly (P > 0.05) different. Each value is an average of three replicates std. error.

(P < 0.05) greater compared to NM un-amended soil (Figure 10). Concentration levels of soluble sugars in tomato fruits (Figure 11) revealed also that YW compost provided the highest concentrations of total phenols among the other amendments tested.

However, one can ask whether the higher content of vitamin C, phenols, and soluble sugars in plants grown in animal manure treatments is due to higher synthesis of these water soluble compounds by plants grown in organic manure, or due to increased absorption from soil by the plants roots, or these compounds were found in the plants due to their presence in native

Figure 11. Concentrations of soluble sugars in tomato fruits of plants grown under different soil management practices. Statistical comparisons were carried out among soil treatments using SAS procedure. Values accompanied by the same letter(s) are not significantly (P > 0.05) different. Each value is an average of three replicates std. error.

soil (soil origin)? Or this increase might be due to increased soil organic matter and microbial activity. Based on the results in Figures 9 and 10, plants grown in NM bare soil (control plants) contained the lowest concentrations of the two phytochemicals (vitamin C and phenols) compared to the plants grown in animal manure amended soils. Therefore, the native soil used in this study is not the source of these three compounds. SS, CM, and HM contain many enzyme substrates such as urea, sucrose, and phosphates compounds that activate soil enzymes, such as urease, invertase, and phosphatase, respectively. Accordingly, the pronounced differences in vitamin C and phenols concentrations found among tomato fruits of plants grown under the different soil amendments tested could be attributed to increased microbial activity and the enzymes they produce. Many reasons have been suggested for this variability, but none of them have been extensively investigated. In either way, the use of animal manure such as municipal waste compost is an economic way to recover nutrients, reduce dependence on inorganic fertilizers, reduce dunghill areas of disposal, and eliminate unpleasant smell [71].

#### 3.3. Impact of agricultural waste on soil enzymes (urease and invertase) activity

Animal manures used as organic soil amendments protect soil microorganisms, soil biological processes, improve soil quality, and increase agricultural productivity [72]. There are three enzymes in soil play a significant role in the N, C, and P cycles. These three enzymes are, urease (urea amidohydrolase, EC 3.5.1.5) is the enzyme that catalyzes the hydrolysis of urea to carbon dioxide (CO2) and ammonium (NH4 + ) ions. Urease breaks-down and converts N from its organic form into inorganic N by hydrolysis of urea or organic forms of N into ammonia. Invertase (β-D-fructofuranosidase) is ubiquitous enzyme in soils. The activity of these two soil enzymes (urease and invertase) in soil is responsible for the release of C and N needed for the growth and proliferation of soil microorganisms and the enzymes they produce. Phosphatases, a group of enzymes that catalyze the hydrolysis of esters and anhydrides of phosphoric acid

(H3PO4), catalyze the hydrolysis of organic phosphate esters to orthophosphate, and thus constitute an important link between biologically unavailable and bioavailable P pools in the soil. Phosphatases are ubiquitous in soil and are produced by microorganisms in response to low levels of inorganic phosphates. Bacteria, fungi, protozoa, and algae secrete soil enzymes such as dehydrogenases, invertase, urease, cellulase, amylases, and phosphatases capable of degrading xenobiotics in soil and water systems improving soil health and plant production. This investigation revealed that CM and HM increased the activities of soil urease (Figure 12), due to the break-down of urea by urease and the release of ammonium ions (NH4

Figure 13. Invertase activity expressed as mg glucose released g<sup>1</sup> dry soil. Statistical comparisons were carried out among soil management practices using SAS procedure. Values accompanied by the same letter(s) are not significantly

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The author would like to thank Steven Diver, Eric Turley, and the University of Kentucky farm crew for their assistance in growing tomato under field conditions. This investigation was

supported by a USDA/NIFA Award No. KYX-10-13-48P to Kentucky State University.

College of Agriculture, Food Science, and Sustainable Systems, Division of Environmental

Whereas, CM and SS increased soil invertase activity (Figure 13).

(P > 0.05) different. Each value is an average of three replicates std. error.

Address all correspondence to: george.antonious@kysu.edu

Studies, Kentucky State University, Frankfort, KY, USA

Acknowledgements

Author details

George F. Antonious

+ –N).

Figure 12. Urease activity expressed as μg NH4–N released g<sup>1</sup> dry soil. Statistical comparisons were carried out among soil management practices using SAS procedure. Values accompanied by the same letter are not significantly (P > 0.05) different. Each value is an average of three replicates std. error.

Biochar and Animal Manure Impact on Soil, Crop Yield and Quality http://dx.doi.org/10.5772/intechopen.77008 61

Figure 13. Invertase activity expressed as mg glucose released g<sup>1</sup> dry soil. Statistical comparisons were carried out among soil management practices using SAS procedure. Values accompanied by the same letter(s) are not significantly (P > 0.05) different. Each value is an average of three replicates std. error.

(H3PO4), catalyze the hydrolysis of organic phosphate esters to orthophosphate, and thus constitute an important link between biologically unavailable and bioavailable P pools in the soil. Phosphatases are ubiquitous in soil and are produced by microorganisms in response to low levels of inorganic phosphates. Bacteria, fungi, protozoa, and algae secrete soil enzymes such as dehydrogenases, invertase, urease, cellulase, amylases, and phosphatases capable of degrading xenobiotics in soil and water systems improving soil health and plant production.

This investigation revealed that CM and HM increased the activities of soil urease (Figure 12), due to the break-down of urea by urease and the release of ammonium ions (NH4 + –N). Whereas, CM and SS increased soil invertase activity (Figure 13).
