3_Review of Literature

Review of Literature Composting and the use of compost offer several potential benefits including improved manure handling, pathogen destruction, enhanced soil tilth and fertility, and reduced environmental risk. Composting is, a broadest term, the biological reduction of organic wastes to humus. Whenever a plant or animal dies, its remains are attacked by microorganisms and larger soil fauna and are eventually reduced to an earthlike substance that forms a beneficial growing environment for plant roots. This process repeated continuously in endless profusion and in every part of the world where plant grow, is part of the overrecurring natural process that supports all terrestrial life. The word compost comes from Old French, bit in sixteenth and 17 th centuries, various spellings were used such as compass, compess, compaste, composture and others, (Deborah and Gershung, 1992 and Wallace and Terry, 1998). The main part of waste production being introduced to soil has always been of organic nature, its humification and mineralization contributed largely to the physical and chemical oil properties favoring growth and nutrition of plants, (Arafat et al, 1992). 1992) . The use of organic manures is important not only in the immediate context of economy in fertilizer use but also in the general interest of maintaining soil at optimum level of fertility and productivity of crop yields satisfactory at high levels, (Patil and Kale, 1983). 1983) . There are a few ways to let nature make compost for us under or over the ground, in bins, boxes, pits, bags, and barrels, in strips, in sheets, in trenches, in 14 months or 14 days, indoors or outdoors. All composting methods aim simply to meet the needs of the microorganisms that do all the work of turning raw organic matter into humus. Those basics need are air, moisture, energy food (carbon) and protein food (nitrogen) in the right proportion, and warmth. Any method involving a pile also needs to be minimum size or critical mass so that high enough temperature can be maintained. Beyond that, we will want to 3

Review of Literature

ensure that there is a culture of the right organisms ready to get started. Although innumerable refinements are possible as long as keep these basic requirements in mind, we can improvise a variety of ways to achieve the desired goal, which is the creation of moist, fragrant fertile humus, (Deborah and Gershung, 1992 and Wallace and Terry, 1998) . Furthermore, obtaining high food quality and production as well. A FAO study (1999) reported that the explicit goal of organic agriculture is to contribute to the enhancement of sustainability. The soil and water protection and the conservation techniques used to combat erosion; compaction, salinization and other forms of degradation are evident in organic farming. Mixed and relay cropping provides a more continuous soil cover and thus a shorter period when the soil is fully exposed to the erosive power of the rain, wind and sun. Terracing to conserve moisture, and soil are used in appropriate situation and particular attention is paid to irrigated areas and to on-farm water management. Properly managed organic farming reduces or eliminates water pollution and helps conserve water and soil on the farm (although improper use of manure can seriously pollute water). 2.1. COMPOSTING Composting is a viable means of transferring various organic wastes into products that can be used safely and beneficially as biofertilizers and soil conditioners. One of the definitions of composting referred to its effect as a biological decomposition of organic materials by bacteria and other organisms, (Frank et al, 2000) and can be conducted by either aerobic or anaerobic methods. However, the aerobic mode is generally preferred, since it proceeds more rapidly and provides greater pathogen reduction because higher temperatures are attained. An example of as aerobic composting method is that developed by USDA scientists. The method is widely referred to as the Beltsville Aerated Pile Method, and utilizes a static pile with forced aeration to maintain aerobic, thermophilic conditions, (Willson, 1989). 1989) .

4


Rynk (1992) has defined composting as a biological process in which microorganisms (Bacteria, Fungi, Actinomycetes, Centipedes, Millipedes, and Earthworms) convert organic materials such as manure, sludge, leaves, paper, and food waste into a soil-like material called compost. 2.2. BENEFITS OF COMPOSTING AND COMPOST 1. Assess the value of composting in recycling farmyard manures and urban organic residues, 2. Identify agricultural uses for finished composts and assure their

use

is

environmentally

sound,

3.

Determine

advantages

and

disadvantages over time of using compost as a fertilizer from a farmer's point of view, 4. Examine the effects of compost use on soil health and crop quality over time, 5. Compare economic and energy costs of compost compared to raw manure and conventional fertilizer and, 6. Address questions about soil health and its relationship to food quality (nutritional and storage) and human health. Furthermore, composting converts the nitrogen contained in manure into a more stable organic form. Although this results in some loss of N, what remains is less susceptible to leaching and further ammonia losses, that was proved by an investigation carried out to study the emission of NH 3, N2O and CH 4 to the atmosphere during composting of source-separated organic household wastes in Sweden by Beck-Friis, 2001; highly bedded manure's have a high carbon-tonitrogen. When applied to the land directly, the excess carbon in the manure causes nitrogen in the soil to be temporarily unavailable to the crop. Composting high-carbon manure/bedding mixtures lowers the carbon/nitrogen ratio to acceptable levels for land application. Also, the heat generated by composting process reduces the number of weed seeds contained in the manure. Angers et al, 1995 , assessed the impact of compost and atrazine applications on soil microbial biomass and activity in a sandy soil used for sweet corn production in Canada. They found that compost application rapidly improved soil quality through increases in microbial biomass and activity, and soil water content. The application of atrazine at recommended rates did not

5


affect soil microbial biomass and activity. The temporal variation in microbial biomass was partly related to soil water content. Compost can provide valuable nutrients and organic matter to soil, (Abou Bakr and Omar, 1996) , depending upon the feedstocks (raw materials used) and upon compost management. A chemical analysis of a representative sample of compost will indicate its total nitrogen, available nitrogen, phosphorus,

and

potassium.

Most

composts

contain

relatively

low

concentrations of one or more nutrients and are not necessarily considered good "fertilizers"; however, as soil amendments, they are good sources of organic matter. Nitrogen and phosphorous in compost are generally found in both plantavailable forms (NO 3, NH4, and P2O5) and organic forms. Much of the nutrients bound in organic forms will be made "plant-available" as the organic matter decomposes. Therefore, readily available nutrients in compost can be much lower than in raw waste, but a "timed-release" effect occurs in the later, slowrelease of nutrients "bound" initially in organic forms. During the composting process, organic wastes are decomposed, plant nutrients are mineralized into plant-available form, pathogens are destroyed, and malodors are abated, (Parr and Hornick, 1992). 2.3. COMMON MATERIALS TO BE USED IN COMPOSTING Materials for composting are all around us. Nearly anything that once lived (and is thus organic) is a candidate for the compost heap. Utilizable biomass and other solid wastes that can be used in composting may be classified under the following principle categories: 2.3.1. CROP RESIDUES These residues include rice, wheat, barely, sorghum, maize and sugarcane. These wastes of shrubs, trees, bananas and oilseed plants can also be used in the compost heap. Generally, the C/N ratio of these residues are wide and they need to be mixed with others having narrow C/N ratio, (Aly, 1999; Hassan, 1999 and Laos et al, 2000) . Also, Dagar and Thampan (1995) reported 6


that organic amendments are important in the reclamation of problem soils for crop production. The extent of degraded and problem soils in India is outlined. Problems include water logging, salinization, erosion, chemical impairment, and desertification. Organic amendments include: livestock wastes, crop residues, green manures, phospho-compost, sugar factory wastes and sugarcane waste, oil cakes, and organic residues. Green manure and other organic amendments have been used in the reclamation of sodic soils. 2.3.2. LIVESTOCK WASTES AND MANURES Many researchers underlined the enormous benefits of the application of organic wastes and farmyard manures and reported that manures are a valuable means for transferring nutrients to the soil, as well as, the plant. Two field experiments were conducted by Mahimairaja et al, 1995 to examine the agronomic value of poultry manure composted in the presence of both phosphate rock (PR) and elemental sulphur (So) (sulphocompost) and PR alone (phosphocompost). Winter cabbage and summer maize were used as test crops. For the first season's winter cabbage, the phosphocompost and sulphocompost were approximately 12 % and 60 % as effective as urea and both composts were equally effective as urea for the second season's maize crop. The greater agronomic effectiveness of sulphocompost could be attributed to the improved nitrogen-use efficiency increased PR dissolution and improved S nutrition. Distribution of NO 3-N in the soil profile of field plots indicated greater potential for winter leaching of N from urea than poultry manure which could be the reason for the improved residual value of the manure reflected in summer maize yields. Results from field experiments indicated that composting poultry manure with so and PR not only reduces environmental pollution associated with manure application, but also increases the agronomic effectiveness of manure and also stated that manures have high nutrient contents and some other physical parameters. In Egypt, there is about 50 millions ton/year of these

7


wastes, and the nutrient of N, P, and K in such amount are 302, 35, and 7 millions kg/year respectively, (Kaloosh, 1997). Epstein et al. (1976) reported that cation exchange capacity (CEC) of sand soil increased as much as three folds as a result of the addition of sludge and compost. Organic matter when added to soil is attacked by microorganisms and transform into other organic compounds, (Simpson, 1986). Much of the carbon is converted to CO 2 and makes no longer-term contribution to the organic matter content in the soil. Other parts of the organic matter are converted to humus, a black or dark brown, colloidal, very complex organic material, which remains in soil. Humus is a very valuable soil component, which increases the ability to hold water available to the plant, and through its very high CEC, reduces the leaching of nutrients. Also, El-Shinawy et al. (1995) studied some chemical, physical and biological characteristics of town refuse compost and chicken manures were investigated. The results showed that both manures contain the principal elements needed for plant growth. However, chicken manure contains characteristics, which render its application to soil more advantageous than does town refuse compost. Also, he found that chicken manure has a larger content of nutrients and a greater water-holding capacity and is also easier to handle. 2.3.3. AGRO-INDUSTRIAL WASTES Mainly organic residues generated in the food processing industry are of special interest. Bagasse and rice husks obtained from sugarcane processing and rice milling plants are of great importance in this regard. Akalona, which represent the waste product in wheat milling industry, (Zein El-Abdeen, 1987) and oilcakes as by-products from oilseed milling industry, (Mekail, 1994) are useful in compost preparation. Elgharably (2002) reported that filer mud cake, vinasse and bagasse ash, sugar industry wastes contain high amounts of NPK and micronutrients and

8


significantly increased the yield of maize crop due to their direct effect at the beginning of the season, and wheat crop due to their residual effect. 2.3.4. URBAN WASTES Urban refuse comprises the solid waste from human dwelling. It contains food wastes, paper and cardboard, cinders and ash. It also contains glass; plastic, metals and commercial refuse from offices. On the other hand, the agricultural wastes contain large amount of vegetable and putrescible wastes. Vegetable, putrescible and paper fraction only in urban refuse can be used in composting. All other materials can cause problems to the composting process, (Murillo et al, 1995). Also, El-Kobbia et al. (1979) concluded that addition of fresh or composted town refuse increased organic matter in clay soil. Last statement came in agreement with what previously published by Badran, 1983; Sakr, 1985; Mahmoud, 1994 and El-Sisi, 1996. 2.4. MATERIALS TO BE AVOIDED IN COMPOSTING Although nearly any organic material can contribute to good compost, there are some that should be avoided, and others to be used only in a limited amounts, (Deborah et al, 1992; Warman and Termeer, 1996; Mahmoud, 1996; Buyuksonmez et al, 2000 and Storm, 2000) . 2.4.1. HUMAN FEES They should not be used unless they have been properly treated and permitted to age sufficiently even then, concerns about disease pathogens make the use of such a material dubious at best for home garden. Urine alone can be used quit safely, however. 2.4.2. DOGES AND CATS FEES They should not be used on the compost pile. Although dog manure is as rich in nutrients as other manure, it is more difficult and less pleasant to handle than the mixed bedding and manure of cattle and sheep. In addition, it may carry organisms parasitic to humans. Cat manure is even more hazardous, especially to pregnant women and small children.

9


2.5. MATERIALS THAT WILL NOT READILY DECOMPOSE Materials such as large pieces of wood, oyster and calm shells, large quantities of rags, brush cornstalk, heavy cardboard should not be used in large amounts unless they are shredded first. 2.6. MATERIALS INHIBITING THE BIOCHEMICAL PROCESSES Materials such as large amounts of grease and oil, toxic material and pesticide treated wastes. Also plant debris from roadsides of the highway, if the highway is a busy one, plant might be coated with lead emission from passing traffic. 2.7. MATERIALS TO BE USED IN COMPOSTING ENRICHMENT There are many materials could be used to increase the compost’s NPK content. Although it is not necessary to add these materials to the heap, many gardeners find it worth the expense to ensure a high nutrient level in their composts. Among the materials and products available are bagged manure, dried blood, bone meal, limestone, cottonseed meal, seaweed and rock powders and other natural product that are valuable to the heap because of their nutrient level. Rock phosphates are excellent materials for enriching the mineral content of our compost. Microbial action makes their nutrients more readily available than they would be if added directly to the soil, (Misra and Sahu, 1992 and Aly, 1999) . Other rock powders such as granite, basalt and tafla, are sources of potassium and micronutrients are similarly made more available to plants when first consumed by compost organisms. Specific materials can also be added by using plants that are especially rich in those elements in our compost. In a field trial, the effects of 4 P sources (single superphosphate, rock phosphate (RP), bone meal and press mud) and 6 microbial treatments (Glomus mosseae, Gl; Gigaspora calospora, Gg; Acaulospora sp., Acal; a Gl+Gg+Acal mixture; the P-solubilizing culture Microphos; and an uninoculated control) on the nodulation, dry matter and yield of chickpea were investigated. Cultivar Phule G-12 was firstly treated with 2 g captan per kg seeds, then with the 4 vesicular arbuscular mycorrhizal (VAM) 10


fungal treatments at 25 g/kg seed or with 50 g Microphos per kg seeds. Seeds were subsequently sown in fields treated with VAM chlamydospores (250 spores/50 ml soil suspension) and infected root segments of guinea grass, and supplied with nitrogen (urea) and the 4 P sources. Data were collected on available N and P, nodulation, dry weight of nodules, shoots and roots per plant at 50% flowering, grain yield and the total dry matter at harvesting. Seeds treated with Gl + Gg + Acal had the highest available N and P (128 and 26.87 kg/ha, respectively) and the highest values for number of nodules per plant (29.50), dry weight of nodules (157.42 mg per plant), shoots (6.91 per plant), roots (500 mg per plant), total dry matter (44.08 q/ha) and grain yield (37.83 q/ha). Among the P treatments, RP recorded the highest values for available N and P (118 and 25.25 kg/ha), shoot dry weight (6.97 g per plant), total dry matter (42.50 q/ha) and grain yield (35.21 q/ha), (Meshram et al, 2000). 2.7.1. ACTIVATORS TO BE IN COMPOSTING Compost activators are any substance stimulates biological decomposition in a compost pile. There are organic and artificial activators. Organic activators are materials containing high amounts of nitrogen in various forms, such as proteins, amino acids, and urea. Some examples of the natural activators are manure, garbage, dried blood, compost and urine. There are two ways in which an activator may influence a compost heap: 1. By introducing strains of microorganisms that are effective in breaking down organic matter and 2. By increasing the N and micronutrients content of the heap, thereby providing extra food for microorganisms. It has been stated by Naguib et al, (1997) that FYM consists of three main groups of components, bedding or litter, solid excreta of the animal and liquid excreta or urine. Sheep manure is high in protein. Horse manure is low in protein. Cow manure is an intermediate in protein, chicken manure is the highest in N, P, and K as well as the most important elements required for plant growth, cattle and horse manure's contain the lowest quantities of these essential elements. Since all the necessary microorganisms are already present in 11


manure, soil, and composting materials, there is no benefit to be gained from introducing strains in the compost from the previous heap or a generous amount of healthy topsoil, (Deborah and Gershung, 1992; Ramaswami and Son, 1993; Abdalla, 1994; El-Ghozoli, 1998; Aly, 1999 and Taha, 2000) . 2.7.2. FUNCTIONS OF BENEFICIAL MICROORGANISMS (EM) •

Fixation of atmospheric nitrogen

•

Decomposition of organic wastes and residues

•

Suppression of soil-borne pathogens

•

Recycling and increased availability of plant nutrients

•

Degradation of toxicants including pesticides

•

Production of antibiotics and other bioactive compounds

•

Production of simple organic molecules for plant uptake

•

Complexation of heavy metals to limit plant uptake

•

Solubilization of insoluble nutrient sources

•

Production of polysaccharides to improve soil aggregation

(Higa and Parr, 1994; Naguib et al, 1997 and Hauka et al, 2001) . The

effect

of

the

application

of

effective

microorganisms

(EM),

Lactobacillus, Rhodopseudomonas, Streptomyces and Aspergillus on the soilroot interface water potential of sweet corn was studied. It was shown that growth and activity of the root system were promoted as soil properties improved and as a consequence the plants became more resistance to soil water deficits, (Xu-HuiLian et al, 1999). Also, the effect of EM on onion and sheep production on a commercial organic farm in New Zealand is reported, and the problems of broad acre application of EM are discussed. In a trial in 1995, the effect of EM and organic fertilizers on onion production was investigated. The highest percentage of first grade onions and the second highest yield were observed in the EM treatment. In 1996, 1.3 ha of onions was intensively sprayed with EM from 6 weeks post emergence to 4 weeks before lifting. Such a treatment induced high yields (53 tons/ha). 12


Fungal diseases were a major problem in storage causing loss of 50 % of the crop. The growth rates of sheep and lambs grazing on EM treated pasture and drinking water was compared in a separate trial. EM lambs had higher liveweight gains for the first 3 and last weighing and has a higher overall live-weight gain. There was no significant difference between the ewe live-weights. Internal parasite faecal egg numbers were lower in EM-treated lambs. EM application recommendations for Asia-Pacific Natural Agricultural Network (APNAN) countries are difficult to implement in a New Zealand farming context, (Chamberlain et al, 1999) . Iwaishi (2000) reported that the effect of an organic fertilizer inoculated with Effective Microorganisms (EM) on the growth, yield and quality of 13 paddy-rice varieties varying with maturation period was studied. EM inoculation increased kernel enlargement after the panicle formation stage and also increased ear number and length and kernel number. The yield of brown rice from EM inoculation was higher for the standard fertilizer rate and lower for the higher rate of organic fertilizer. EM inoculation increased the glutinousness and the total quality index of glutinous rice varieties. Also, Yamada et al, (2000) studied the chemical, physical and microbiological properties of an organic fertilizer comprising molasses, rice bran, rice husks, oilseed rape mill cake, and fish meal that was inoculated and fermented with microbial inoculants (Effective Microorganisms). The quality estimation methods employed addressed the mechanistic basis for beneficial effects of soil improvement and crop yield. Effective microorganisms were utilized as the microbial inoculants, which is a mixed culture of beneficial microorganisms. Tests showed that the fermented organic fertilizer contained large populations of propagated Lactobacillus spp., Actinomycetes, photosynthetic bacteria and yeasts; high concentrations of intermediate compounds such as organic acids and amino acids; 0.1 % of mineral nitrogen mainly in the ammonium form, 1.0% available phosphorus; and a C: N ratio of 10. The quality of the fermented organic fertilizer depends on the initial water content; addition of molasses as a carbon and energy source; and 13


the microbial inoculants. The medium pH appears to be of reliable fermentation quality for producing this organic fertilizer. The beneficial effects of the fermented organic fertilizer on soil fertility and crop growth will probably depend upon the organic fraction, the direct effects of the introduced microorganisms, and indirect effects of microbially-synthesized metabolites. 2.8. FACTORS AFFECTING THE COMPOSTING PROCESS Composting provides as appropriate porosity, density and moisture content so easily degraded components of the substrates are broken down, while at the same time pathogens and weed seeds are killed and the organic materials become stabilized. Composting processes should be under controlled conditions. Temperature, water content, C : N ratio, pH level, aeration rate and the physical structure of organic materials are important factors influencing the rate and efficiency of composting. Homogeneous manure solids can be composted alone without mixing with bulk materials. Bulking agents are needed to provide structural support when manure solids, or other organic residues, are too wet to maintain air spaces within the composting pile, and to reduce water content and/or to change the C : N ratio. Dry and fibrous materials, such as sawdust, leaves, finely chopped straw or peat moss, are good bulking agents for composting wet manure or organic residues. An important problem is how to estimate the degree of compost maturity. There are number of factors which affect the composting process and which must be within an optimum range if aerobic, thermophilic composting is to proceed rapidly and effectively, (Willson, 1989). 2.8.1. CARBON : NITROGEN RATIO During composting, microorganisms require carbon for growth and energy, and nitrogen for protein synthesis. Thus, the rate of decomposition of organic wastes depends on a proper balance of carbon and nitrogen. Rapid composting is achieved when wastes or mixture of wastes have a C : N ratio of between 1 : 25 and 1 : 30, (Kayhanian and Rich, 1996) . Lower ratios can result in the loss of ammonia (NH3), while higher ratios can slow the rate of composting. According 14


to Chanyasak and Kupota (1981) , the C/N ratio of sufficiently well composted material varies widely from 5 to 20 depending on the type of raw materials. 2.8.2. MOISTURE CONTENT Moisture content between 40 % and 60 % is a good target range, (Mathur et al, 1993). Moisture is needed for microbial activity, but excessive moisture inhibits gas exchange and may result in anaerobic conditions. The compost mixture should feel moist to the touch, but not be soupy. Very wet feedstocks may be dried before mixing, or a dry bulking material can be used to absorb moisture. Consider protecting the compost piles from excessive rainfall or pounded water. Some moisture will be removed from the mixture during the composting process. During dry weather, the mixture may need water added to maintain moisture. The optimum content of organic wastes or mixtures of wastes for rapid aerobic, thermophilic composting ranges from 40 to 60 % (by weight). If the moisture content is below 40 %, decomposition will be aerobic but slow. If it is above 60 %, they may be insufficient air space (because of excess moisture) to sustain aerobic decomposition and anaerobic conditions may prevail. 2.8.3. TEMPERATURE As composting proceeds, and if other factors are favorable, microbial activity causes temperatures to increase from mesophilic range (20 – 40 C) into the thermophilic range (> 40 C). Optimum temperatures for rapid aerobic composting from 55 to 70 C, (Murillo et al, 1995 and Illmer and Schinner, 1997) . Temperature is the most common indicator of how composting is progressing. Elevated temperature is necessary to destroy pathogens and weed seeds in manure or other organic materials. Environmental Protection Agency (EPA) regulations for composting municipal waste require that the temperature be maintained at 65 C or above for at least three days to destroy pathogens. A temperature of 75 C within the compost pile is needed to destroy weed seeds. Depending on the ambient temperature, a complete composting process may take two to six months. The water content of mature compost should be less 15


than 50 percent and preferably in the range of 30 to 35 percent. The C : N ratio should be less than 20. 2.8.4. pH Measuring the concentration of the active hydrogen can be important. Microorganisms

tend

to

modify

their

environment,

and

products

of

decomposition may alter pH over time. Near-neutral pH is preferred for most efficient microbial activity. Specific plant species can flourish when grown within a specific pH range, and based on typical compost application rates; it is understood that the addition of compost can affect the pH of soil and growing media. Therefore, to estimate the effect, which in turn will affect soil maintenance practices or growing system management, the pH of compost must be known. The pH of compost products typically ranges from about 5.0 to 8.5. More commonly, the pH of the finished product is in a narrower range of 6.0 to 7.5. During the composting process, biological activity will tend to neutralize the feedstock pH as the composting process progresses.

In the early most

active stage of the composting step, it is not uncommon for a temporary pH depression to occur. This is the result of aerobic surface degradation of large particles and anaerobic degradation below the surface, accompanied most often by a lack of adequate aeration to supply oxygen and displace carbon dioxide and other gases. This pH depression is followed by an increase, as particle size reduces and microbial populations shift from dominance by bacteria to actinomycetes and fungi, and the oxygen content within the composting mass improves. However, if prolonged anaerobic conditions persist in the composting and/or compost curing and storage steps, then organic acid build up will tend to occur, thus depressing pH. In the feedstock preparation step pH is largely impacted by pH of the feedstock materials. For example, if materials with a source, which buffers pH, such as wood ash or certain industrial residuals, are composted, pH of the resulting compost product will tend to be above neutral. Similarly, if lime or ferrous salts are used to dewater biosolids in municipal applications, pH of the resultant product will tend to be 16


above neutral. If, on the other hand, yard trimmings that are rich in soft wood, leaves, or pine needles are the primary feedstock materials, the resultant product will tend to be more acidic. During the composting and compost curing steps, the biggest pH impact tends to be the lack of aeration and the resultant formation of organic acids. Product pH can be improved by maintaining pile porosity and free airspace during composting and compost curing, by use of a suitable bulking material and by frequent turning to break up clumps and air channels as an aid to aeration whether by forced aeration or convective aeration. Another common problem occurs during the compost-curing step when the lack of aeration and large storage piles tend to increase production of acids, thereby depressing product pH. Retaining bulking material in the pile until just prior to distribution will help provide the needed porosity. Positive aeration can be provided during compost curing and storage using small blowers providing air to a diffuser system beneath the piles. Turning compost-curing piles for aeration can improve pile oxygen percent. Decreasing pile heights to six feet or less to avoid slump and compaction is a method that can be used to improve the oxygen content of the material, thereby decreasing acid production. The final product can be adjusted by the addition of amendments, such as liming agents to increase pH or sulfur products to lower pH if desired for specific applications. Some food processing wastes and industrial wastes may exhibit levels of alkalinity or acidity that inhibit nutrient availability or microbial activity. Chemical analyses of material samples will indicate whether pH or nutrients need to be adjusted. Research has shown that the optimum pH for rapid composting of various wastes or mixtures of wastes ranges from 5 to 9. 2.8.5. AERATION / OXYGEN SUPPLY It is possible to make compost without air, or anaerobically, through the activities of a different type of organism. However, most composting systems are aerobic and so require adequate air throughout the pile. Aerobic bacteria are also thought to more causing either acidic or putrefaction of the heap producing bad odorous, (Sarapatka et al, 1993). The optimum airflow 0.6 to 1.8 17


m3 airs per day per kg volatile solids during thermophilic stage or maintains oxygen level at 10 to 18 %. A continuous supply of oxygen is required to ensure rapid aerobic, thermophilic composting. A rile-of-thumb is that the composting biomass must contain at least 30 % free air space (i.e., total porosity). 2.8.6. PARTICLE SIZE / TEXTURE The particle size is an important factor, as the microorganisms need a large surface area for their attack. The particle size below 5 cm is desirable, (Mathur et al, 1993 and Taha, 2000) . So that grinding, shredding and blending organic wastes can enhance the rate of decomposition during composting by providing a more favorable surface to volume ratio. However, excessive grinding can lead to compaction, loss of porosity, and anaerobic conditions. 2.8.7. BULK DENSITY It should be low enough (less than 40 lb/ft 3) to allow for good aeration. Dense manures and sludge can be "lightened" by adding of bulking agents, such as wood chips, corncobs, and straw. 2.8.8. INSULATION Material can be used if cold weather keeps compost temperatures down. It also can help reduce odor emissions from a pile. Preferred insulation materials include finished (recycled) compost and/or bulking materials. Almost any organic material can be composted. The main objectives of C: N ratio, moisture content, and bulk density can be achieved with a variety of feedstock combinations. Therefore, gardeners and farmers alike often can easily identify likely

"recipes"

from

materials

on-site.

Some

suggestions

include:

I.

Combinations of poultry litter with bedding material and additional carbon-rich bulking materials, including (1) broiler litter containing wood shavings as bedding material composted with peanut hulls; and (2) broiler litter containing wood shavings as bedding material composted with shredded pine bark, (Flynn et al, 1995). II. Municipal biosolids composted with combinations of sawdust, yard wastes, bark, vegetable trimmings, animal bedding and manures. III. Ground (shredded) yard wastes, dairy manure, and food processing wastes. If 18


all of these factors are optimal, composting proceeds as indigenous microorganisms start to utilize the organic materials for available carbon, nitrogen, and other nutrients. As the activity continues, the temperature begins to increase from heat that is generated through microbial oxidations and respiratory functions. Composting is completed when the pile no longer generates heat and the original organic materials are no longer recognizable. The composting process has then reached an endpoint and is more or less biologically stable. Finished compost is not a good substrate for growth of pathogens, but if it has been recontaminated with fresh manure, it may act as a carrier for pathogens, (LeaMaster et al, 1998). 2.9. COMPOST EFFECT ON SOIL PHYSICO-CHEMICAL PROPERTIES A pot experiment was conducted to assess the effect of different kinds of composts on the growth and nitrogen (N) composition of Chinese mustard (Brassica chinensis) in acid red soil. Pea residue

compost, cattle manure

compost, two pig manure composts (A and B), a lime-chemical fertilizer treatment and a control plot of conventional chemical fertilizer were used. The plants were harvested 37 days after transplanting and the growth and N composition of these plants were measured. The soil was also sampled, and selected chemical properties were determined after harvesting the plants. The results showed that different composts affected the growth and soil chemical properties significantly. The pH, NO 3-N, NH4-N, electrical conductivity, and 1N ammonium acetate exchangeable K, Ca, Mg, Al, Mn, and Fe were all significantly affected by the compost treatment. The growth of plants in the control treatment was significantly lower than that of the compost-treated and lime-treated plants, suggesting that the acid Oxisol is unfavorable for the growth of Chinese mustard. Some composts could increase the growth of Chinese mustard. The lime-treated plants had higher concentrations of chlorophyll a and chlorophyll b than those of the compost-treated plants. There were no significant differences between treatments in the concentrations of chlorophyll a 19


and chlorophyll b; however, there was a close correlation between the total chlorophyll concentrations and the shoot yield of the plants. The NO 3-N, soluble reduced N, and insoluble N concentrations in leaf blades and petioles of Chinese mustard varied significantly according to the compost applied. The pig manure compost B could adequately supply nutrients especially N for plant growth and caused little NO 3-N accumulation in plant tissues, (Chung et al, 2000). Fertilizer is an essential part of any vegetable production system. Compost application to commercial vegetable crops is relatively new. Research has demonstrated that compost can serve as a soil amendment to improve soil moisture and nutrient holding capacity, (Obreza and Reeder, 1994 and Stoffella et al, 1997), particularly in sandy soils; increase soil organic matter; and ultimately improve plant growth and yields, although, the application of compost to vegetable has generally but not always, given a significant yield response. Some experiments on the use of organic, organic compounds and chemical fertilizers for green onion have been carried out in Taiwan. Fertilizer applications were adjusted in order to make up the same level of N – P – K (180 – 100 – 160 kg / ha). These experiments are still at an early stage, but so far they have shown yields from plots with organic compounds fertilizer to be higher than those with chemical fertilizer, (Juang, 1996). Compost may be utilized as an alternative weed controller, (Roe et al, 1993), and to increase soil tilth and fertility in vegetable crop production systems, (Peter et al, 1997). Also, Gurung and Sherchan (1993) have stated that compost applied as a soil amendment can improve soil organic matter, the water and nutrient retention in soils susceptible to leaching, stabilize soil pH, and could be a source of micro and macronutrients. However, these benefits can be reduced in hot humid climates, in which the decomposition of organic matter is faster than in temperate climates. The use of organic materials as mulches can slow the evaporation of water from the soil surface, moderate soil temperature, serve as a source of slow release nutrients, reduce the germination of weed seeds and subsequent weed growth, and protect soil from erosion and structural breakdown by sun, 20


wind, and rainfall. That was in line with what Baskin and Baskin (1987) proved when they studied the effect of organic mulches on weed, they found that weed seed germination declines as the depth of the covering layer increases, probably due to unfavorable conditions such as high or low temperature, absence of sufficient moisture, O 2, light, and high CO 2 levels. Anonymous (1987) and (1992) confirmed that organic mulch improved the soil by increasing microbial activity in the soil and controlling soil temperature. Same results have been achieved in Asia, while studying the effect of organic materials and animal manures on soil microorganisms. It was reported that organic products are a major source of organic matter for agricultural soils. It contains significant amounts of N and P, (Van Erp and Van Dijk, 1992; Van Lune et al, 1993 and Velthof et al, 1998). One study found that application of livestock manure and other organic materials resulted in more diverse root fungal flora. Solid organic materials produced more diversification than liquid ones. Thus, microorganisms are useful in eliminating problems associated with the use of chemical fertilizers and pesticides; they are now widely applied in nature farming and organic agriculture, (Higa, 1994 and Parr et al, 1994) . Also, the use of crop rotations, organic manure and mulches increased the soil pH; the main reason for manure to raise the soil pH is due to the lime like materials such as Ca and Mg in the manure, (Zhang, 1998) and, organic matter content. Hence, improves soil structure and encourages the development of a vigorous population of soil microorganisms. Delschen (1999) argued that after a long term field experiment carried out to study the impact of application of organic fertilizers on soil quality parameters that, the regular input of organic matter (manure, waste compost, sewage sludge) favors the accumulation of soil organic matter. However, the type of organic material applied influence annual accumulation rates in the first years after reclamation. Also, it seems to be less important for the long-term accumulation process than the application rate. This is also important for 21


composted and uncomposted manure; nevertheless, the application of similar amounts of organic C in the form of manure resulted in a higher accumulation of Soil Organic Matter (SOM) in nitrogen reduced farming system. Decomposition of plant residues and nutrient cycling are the most important soil processes related to soil fertility and stability, (FAO, 1999). In Organic farming, crop rotation is a widely used method of fertility maintenance and pest and disease control, moreover, it encourages a diversity of food crops, fodder and under-utilized plants; this in addition to improve overall farm production and fertility may assist the on-farm conservation of plant genetic resources. Scialabba (2000) wrote that crop rotation is a valuable tool for weed control, maintenance of soil structure and organic matter, recycling of plant nutrients, contribution to overall species and habitat diversity, preventing erosion, and green manuring. Composting and application techniques of manure have to be optimized in order to guarantee a nutrient transfer to the plants with minimum losses and adapted to the requirement of plants. The most basic requirement for every type of composting method is the correct choice and preparation of the used compost materials. Factors that are important include the C : N ratio, humidity and ventilation. The ratio in the materials chosen should ideally be 25 - 30 : 1, this may be higher at warm, humid sites. The same level of productivity, both quantitatively and qualitatively, is maintained by replacing cattle manure with compost, (Beyea et al, 1993 and Roe et al, 1993). An 8 years study was set up at the Sustainable Agriculture Farming System in USA by Clark et al, (1998), to document changes in soil fertility status and nutrient storage during the transition from conventional to organic farming practices, Four farming systems differing in crop rotation and in the use of external inputs were established on land that had been previously managed conventionally. Fertility in the organic system depended upon animal manure applications and winter cover crops while the two conventional systems received synthetic fertilizers input. After 4 years of production, soils in the 22


organic and low-input system had higher soil organic C, soluble P, exchangeable K, and pH. Whilst, discontinuation of manure application in the low-input system in the 4th year resulted in declining levels of organic C, soluble P, and exchangeable K. Differences in crop rotation also had a significant effect on the organic C levels due to the presence or absence of corn in the cropping sequence. Differences in total N appeared to be related partially to inputs, the low-input system appeared to be the most efficient in storing excess N. Electrical conductivity (EC) levels were relatively stable in the organic system thereby showing that the use of animals' manures has not resulted in increased salinity. Another study was conducted by Adetunji (1997) to evaluate the effects of organic residues treatment on soil nutrients after clearing a 3-year secondary fallow land. Burning the fallow and crop residue led to significant increases in soil pH, total N, organic matter, available P, exchangeable K within one month in both fertilized and unfertilized treatments. In fertilized one the increases due to residues incorporation were small but more sustainable, while in bare unfertilized plots the nutrients decreased below the pre treatment levels throughout the period of the experiment. Another investigation focused on studying the application of different rates of compost to artificial field plots of a low humic Andosol in Japan for 15 or 28 years, and their effects on the chemical properties of wheat rhizosphere soil and non-rhizosphere soil measured. Continuous application of compost for 28 years resulted in an increase in soil C, N, P, pH, and exchangeable bases. The build up of organic matter in the soil occurred slowly. A residual effect of the compost on soil chemical properties was still present after 13 years of no application, but this effect was weaker in comparison with that of the continuous application. In the rhizosphere soil, NaHCO 3-extracted P and exchangeable Ca were higher than those in the bulk soil. The removal of free organic acid slightly affected the soil pH, especially in the rhizosphere soil. The increase in soil pH resulted from an increase in exchangeable bases through the application of compost, (Shen 23


et al, 1996). As proved by Ott et al, (1983) Composted FYM led to the greatest increase in both soil organic matter and soil nitrate content in the top 30 to 40 cm. These results were in a close agreement with those obtained by Matsumura and Witjaksono (1999), they studied the impact of farmyard manure in comparison with chemical fertilizer and mixture of organo-mineral fertilizers on some crops on rotation (oats - soybean and wheat – corn). Results showed that FYM significantly affected the yield of wheat – corn crops, and soil pH, total nitrogen and microbial biomass nitrogen, but only in the soil surface layer (0–20 cm). Amounts of soil organic matter changed in accordance with the amount of crop residues reincorporated, especially in the surface layer. El-Emam (1999) conducted a trial aiming at spotting the light on the effect of some composted plant materials and organic manures on the macronutrients status in two textured soils. Results obtained indicated the significant increment of total N and available P in the soil accordingly on the order of biogas manure sludge < composted broad bean straw < composted zea maize stalks < FYM. 2.10. THE EFFECT OF COMPOST ON ORGANIC CROPS Sawan et al, (1999) studied twenty-five combinations of peat, vermiculite, composted sawdust (composted for 1, 2, 3 or 4 months) and crop residues compost as growing media for cucumber (cv. Katia) seedling production. Results obtained showed that the best plant growth and the highest yield were obtained by mixing the control medium with sawdust and plant residues compost 2:2:1 (v/v/v). These results indicate that sawdust can be used as a substitute for high percentages of peat in media for cucumber seedling production. Another field trial held to study the effect of composted crop residues (sesame straw, water hyacinth and peanut straw) at a different application rates (5, 10, 15 tons/fed.) on the soil chemical and physical properties as well as crop growth (corn) and production, organic carbon decreased. On the contrary, NPK and Micronutrients significantly increased which reflected in decreasing C/N ratio as compared to the raw organic residues, (Taha, 2000). 24


Gurung and Sherchan (1993) studied the effects of long-term applications of compost and chemical fertilizers alone, or in different combinations, on crop yields were studied in a field experiment under a rice-wheat cropping pattern in Nepal. In the fourth year the residual effect of the compost treatments applied to wheat was observed on the succeeding rice crop. The grain yields of rice produced from 15 t/ha compost alone, 15 t/ha compost supplemented with 30 kg/ha nitrogen top dressing and 15 t/ha compost plus 60 : 30 : 30 kg/ha N, P and K were significantly higher than with chemical fertilizers only and the control treatments. The response of rice to potassium has also been observed. In the fourth year, grain yield of wheat was greatest from an application of 15 t/ha compost plus 60 : 30 : 0 kg/ha N, P and K which was significantly higher than the control, 15 t/ha compost and 60:30:30 kg/ha, N, P and K treatments. Another field experiment was conducted to study the effect of organic manure and inorganic fertilizers on growth, yield and quality of kharif onion cv. Agrifound Dark Red. The organic manures evaluated were sunflower cake at 19 q/ha, poultry manure at 57 q/ha and FYM at 143 q/ha and 72 q/ha. The inorganic fertilizers evaluated were urea at 252 kg/ha, CAN 444 kg/ha and ammonium sulfate at 565 kg/ha. The control plot was maintained without any organic/inorganic fertilizer. The bed size was 3.6 x 1.8 m. The studies revealed that FYM at 72.0 q/ha along with ammonium sulfate at 565 kg/ha were effective in increasing the growth, yield and quality contributing characters such as bulb color, compactness, TSS and dry matter and gave the highest net return, (Gupta et al, 1999). Also, In a pot study with tomato cv. Paiyur 1, using a soil neutral in reaction with a low salt concentration and poor organic carbon, the following treatments were assessed: T1, control; T2, 100% soil-test-based NPK + ZnSO4 (50 kg/ha) + borax (10 kg/ha); T3, T2 + Tankslit [no details given] (40 t/ha); T4, T2 + composted coir pith (5 t/ha); T5, 75% soil-test-based NPK + ZnSO4 (50 kg/ha) + borax (10 kg/ha) + Tankslit (40 t/ha); and T6, 75% soil-testbased NPK + ZnSO4 (50 kg/ha) + borax (10 kg/ha) + composted coir pith (5 t/ha). T4 recorded the highest fruit yield of 1487.0 g/pot compared with 447.5 25


g/pot in the control. The dry matter production, content and uptake of nutrients, and the residual soil fertility were favorably influenced by this treatment, (Balasubramaniam et al, 1998) . A field experiment was conducted to study the effect of organic and inorganic manures on adult coconut palm. The treatments comprised of control, 100% of recommended dose of chemical fertilizers (1.3 kg urea + 2 kg single superphosphate + 2 kg muriate of potash per palm per year), composted coir pith (CCP) at 50 kg per palm per year, 50 % CCP (25 kg) + 50% of recommended dose of chemical fertilizers, 2 kg neem cake + 0.5 kg bone meal + 4 kg ash per palm per year, farmyard manure (FYM) + recommended dose of chemical fertilizers. The results revealed that application of 50 kg FYM, along with the recommended dose of NPK, recorded the highest N, P and K content in soil and leaf, with 47% higher nut yield compared to the control, (Marimuthu et al, 2001). Rice plants grown in a field experiment were treated with: organic products (OP) I-IV combined with 75 or 50 % NPK; 100 % NPK; and a control (no fertilizer or manure applied). OP I consisted of poultry manure, fish scraps, bone meal and neem cake; OP II consisted of goat droppings, poultry manure, bone meal and neem cake; OP III consisted of cow dung, poultry manure, fish scraps and neem cake; and OP IV consisted of cow dung, goat droppings, fish scraps and bone meal. Treatments with OP I-IV + 50 or 75% NPK at 1 t/ha resulted in higher grain and straw yields than treatments with 100% NPK and the control. OP + 75% NPK increased the absorption of the major nutrients (N, P, K, Ca and Mg), while OP + 50% NPK treatment did not. The OP IV + 75% NPK treatment resulted in the highest grain and straw yields, and the highest mineral uptake, (Bhoite et al, 2000). Another investigation by Jak et al, (1999) showed that farmyard manure (FYM) and compost from chicken deep layer manure and bark were compared to mineral fertilization (NPK) and to non-fertilized control plots. The amount of added fertilizer was adjusted to a total N supply of 200 kg/ha for cabbage 26


production and 100 kg/ha for the following spinach production. Results showed that the highest yield (8500 kg dry matter/ha) was obtained with mineral fertilization where N was supplied twice (before transplanting and during head formation), followed by mineral fertilization in which the whole amount of N was added at transplanting time (7900 kg d.m. /ha), then the treatment fertilized with FYM (6000 kg d.m. /ha), compost (4200 kg d.m. /ha) and, finally, the control (3700 kg d.m. /ha). A field experiment was conducted by Bhardwaj et al, (2000) during 199598 at Jachh to find out the effect of organic sources of nutrients, i.e. FYM, neem cake and rapeseed cake as partial or complete alternative to chemical fertilizers on yield of tomato, okra, cabbage and cauliflower and its economic feasibility. Application of sole organic sources of nutrients recorded 11 - 17% lower yield in different vegetable crops. However, application of 50% recommended NPK + 50% rapeseed cake (0.72 ton/ha) in tomato, 50% recommended NPK + 50% neem cake (0.72 ton/ha) in okra, 33.3% recommended NPK + 33.3% farmyard manure (6.66 tons/ha) + 33.3% rapeseed cake (0.48 ton/ha) in cabbage, 33.3% recommended NPK + 33.3% farmyard manure (6.66 tons/ha) + 33.3% neem cake (0.48 ton/ha) in cauliflower recorded higher yield which were statistically at par with recommended doses of chemical fertilizers. Net returns in organic produce of different vegetables were higher as the produce received higher price in the market. El-Shinawy et al, (1999) conducted a field trial, lettuce (cv. Calona) plants grown under nutrient film technique (NFT) conditions were supplied with inorganic fertilizer (control), chicken manure, pigeon manure or buffalo manure, for 2 seasons. The electrical conductivity of the nutrient solution was maintained at 1.8-2 mmhos/cm while pH ranged between 5.5 and 6.5. Head fresh and dry weights, chlorophyll content and mineral composition (total NO 3-N, P, K, Ca, Zn, Mn, Fe and Cu) were determined. Yield was highest in the control treatment, followed by chicken manure; pigeon manure and finally buffalo manure. Mineral composition of plants was influenced by treatment. The results suggested that 27


chicken manure, with some modifications, could be used as an organic source under the nutrient film technique system.

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3_Review of Literature

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