**2. Justification for using organic amendments in agricultural production**

As more municipal sewage sludge (SS) treatment districts turn to composting as a means of sludge stabilization and because of the rapid growth in the poultry industry, significant chicken manure (CM), and municipal SS generation will become available in increasing quantities. Recycling wastes such as SS and CM for use as a low‐cost organic fertilizer resulted in a positive effect on the growth and yield of a wide variety of crops and promoted the restoration of ecologic and economic functions of soil. The organic matter content of composted soil amendments is high, and its addition to agricultural soils often improves soil physical and chemical properties and enhances soil biological activities. Composts provide a stabilized form of organic matter that improves the physical properties of soils by increasing nutrient and water holding capacity, total pore space, aggregate stability, erosion resistance, temperature insulation, and decreasing apparent soil density [3, 4]. Antonious et al. [5–8] reported that SS and CM, that must be disposed, are excellent fertilizers.

**1. Introduction**

158 Organic Fertilizers - From Basic Concepts to Applied Outcomes

effects.

future.

Organic fertilizers are derived from municipal sewage sludge (SS), or chicken manure (CM), horse manure (HM), blood and bone meal, and all manures are examples of organic fertiliz‐ ers. Organic fertilizers also include vegetable matter (i.e., cottonseed meal, vegetable remains, and yard waste compost). There is often low available concentrations of nutrients in organic fertilizersusedinagriculturalproduction.However,organicfertilizershaveimportantfunctions that cannot be gained from synthetic inorganic fertilizers, they increase soil organic matter, improve soil physical structure, enhance soil fungal and bacterial activity, and reduce eutro‐ phication (excess N and P in natural water resources), provide low‐cost adsorbents that binds with agricultural contaminants and prevent natural water contamination by pesticides and inorganic fertilizers [1], and hence, reducing the impact of xenobiotics on surface and ground‐ water quality. In addition, over the last 50 years, the amount of N and P pollution entering our nation's waters has escalated dramatically. Thirty percent of US streams have high levels of N and P contamination and drinking water violations due to nitrates and phosphates that have been doubled in the last 8 years [2] due to over application of inorganic fertilizers. According‐ ly, environmentallyandeconomicallyviableagriculture requires theuseof cultivationpractices and innovative technologies that maximize agrochemical efficacy while minimizing their side‐

Organic farming "farming without chemicals" requires organic fertilizers. While such a definition is concise and clear, it is unfortunately untrue and misses out on several character‐ istics which are of fundamental importance. All materials, living or dead, contain chemical compounds; therefore, organic farming utilizes chemicals. The United States Department of Agriculture (USDA) has framed a handy definition of organic farming: "Organic farming is a production system, which avoids or largely excludes the use of synthetically compounded fertilizers, pesticides, growth regulators, and livestock feed additives." The potential health hazards of pesticide residues, nitrates, and phosphates resulting from conventional agriculture are now receiving attention. There is growing scientific evidence about the positive quality aspects of organically produced food like higher dry matter and vitamin content and improved storage quality. Unlike conventional agriculture, organic farming has not been blessed with extensive research and development, nor have organic farmers had the back‐up of advisory services. Organic farming needs a continued research efforts, and it is agriculture for our

**2. Justification for using organic amendments in agricultural production**

As more municipal sewage sludge (SS) treatment districts turn to composting as a means of sludge stabilization and because of the rapid growth in the poultry industry, significant chicken manure (CM), and municipal SS generation will become available in increasing quantities. Recycling wastes such as SS and CM for use as a low‐cost organic fertilizer resulted in a positive effect on the growth and yield of a wide variety of crops and promoted the restoration of ecologic and economic functions of soil. The organic matter content of composted soil amendments is high, and its addition to agricultural soils often improves soil physical and

Demand for food is ever increasing and much of future plant production systems will depend on fertilizers. In the United States, about 317 million tons of animal manure is produced annually from about 238,000 animal feeding operations [9], and nearly 90% of about 11.4 million tons of poultry litter produced annually is applied as fertilizer [10]. The current rapid growth in the poultry industry has resulted in significant manure generation [11]. Poultry litter contains all essential plant nutrients (N, P, K, S, Ca, Mg, B, Cu, Fe, Mn, Mo, and Zn) and has been documented as an excellent fertilizer [12]. SS is rich in organic matter, and it acts much like slow release organic fertilizer that maintains productive soil and stimulates plant growth [13, 14]. The use of CM and SS as soil amendments in land farming provides a constructive means of waste disposal and a viable method for improving soil fertility and physical prop‐ erties [14, 15]. Agricultural uses of SS have shown promise for a variety of field crops (e.g., maize, sorghum, and forage grasses) and production of vegetables (e.g., lettuce, cabbage, beans, potatoes, and cucumbers) [3,4]. The literature review revealed that there is lack of information regarding the impact of organic amendments on plants nutritional and antioxi‐ dant properties. Investigators have focused on the plant yield and soil physical and chemical properties following the incorporation of soil amendments with very little information on the plant nutritional and antioxidant contents. Chemical analysis of soil amended with CM and SS revealed a significant increase in organic matter, N, P, and K content, the primary nutrients required to achieve target crop yields. Vitamin C concentration decreased in the leaves of collard and kale greens grown in no‐mulch native soil compared to plants grown in CM and SS amended soil [16].

Addition of organic amendments, such as yard waste compost [17], straw [18], manure [19], tree leaf mulch [20], wood products [21], chipped wood from twigs [22], have been found to increase soil organic matter. The literature review indicated that leaves of collard plants grown in soil amended with SS contained the greatest concentrations of glucosinolates (bioactive compounds) which could play a significant role in sustainable agriculture as alternative organic tools for soil‐borne disease management in conventional and organic agriculture [1, 23, 24]. High‐quality kale plants (US No. 1) obtained from SS and CM amended soil were also greater compared to no‐mulch native soil. In a similar study, total pepper fruit harvest was increased by 15 and 34% after the addition of CM and SS, respectively, to native soil. Whereas the number of cull fruits, the fruits that failed to meet the requirements of the USDA grades, was low in soil amended with yard waste (YW) compared to SS and CM amended soils [25].
