Impacts of Different Compost Types Application on Soil Fertility and Plant Growth

This study aims at evaluating the impacts of applying different compost types produced in Alexandria city on the soil and plant. Composting is the biological decomposition and stabilization of organic substrates. It is a means of converting objectionable wastes, such as sewage sludge, garbage, organic trash, food processing wastes and farm manures into materials suitable for application to land. Sandy soils and four types of compost with different rates were applied; composted sewage sludge, Composted domestic solid waste, composted plant residues, and composted animal manure. The Tested plant was Wheat (Giza 75). Pot experiments were carried out at lab. the results revealed that application of different types of compost to sandy soil cultivated with wheat plant increased soil salinity (EC), organic matter (OM), available nitrogen, and trace element (Fe, Mn, Zn, Cu, Cr, and Pb) contents while decreased pH and available phosphorus. As the soil treated with different compost types were enriched with macro and micronutrients, the fresh plants and oven-dried weights of the plants of treated soil were higher than those of plants of untreated control soil. It is clear that sewage sludge and domestic solid wastes composts application indicated a highest plant yield among other compost types. This study recommended Application of sewage sludge compost must be under special control, Application of domestic solid wastes could be used at the rate of 10 and 20% for sandy soil, plant residues compost could be applied on sandy soil, at the rate of 10% only for cultivation of all crops, and Application of animal manure compost could be applied at the range of 20-30% in case of sandy soil for all crops. INTRODUCTION Over the past 50 years, the disposal of urban wastes has become increasingly difficult problem (1). Landfill has always been the most common disposal method and is likely to remain so, but when sites close to a city have been filled up additional expenditure is necessary to transport the wastes to more distant sites. Thus, it has become more and more important to discover treatment methods which reduce the volume of wastes to be accommodated on scarce landfill sites(1). Composting can have permanent and farreaching effects on the quality of the 307 Bull High Inst Public Health Vol.38 No. 2 [2008] environment by removing large amounts of refuse from the waste stream, thereby reducing land filling and incineration of wastes(2). Haug(3) has described composting as the biological decomposition and stabilization of organic substrates, under conditions that allow development of thermophilic temperatures as a result of biologically produced heat, to produce a final product that is stable, free of pathogens and plant seeds, and can be beneficially applied to land. Composting is used also as a means of converting objectionable wastes, such as sewage sludge, garbage, organic trash, food processing wastes and farm manures into materials suitable for application to land (2). The most commonly composted materials include those which are familiar to most people. Kitchen vegetable scraps, yard clippings and wastes from landscaping and farming activities. Most of these materials, with the exception of the most recalcitrant woods and leaves, are easily compostable in the personal backyard compost pile. On an industrial level, many communities are investigating roadside pickup, chipping of materials, and large-scale composting of green wastes in a municipal setting. Composting of biosolids or animal manures is a means of reduction or stabilization of wastes prior to utilization on land or disposal (4). Compost as managing organic wastes, possess a low risk to the environment assuming it is free of heavy metals or hazardous organic materials(5); improves soil fertility whether in backyard gardens or reclaimed strip-mine soils; its product furnishes the soil with many of the rare elements essential for plant growth; it retains moisture and increases biological life in the soil; stimulates the rate of root growth; and it has relatively higher content of nitrogen, phosphorus and organic matter(6). Wheat straw, corn stalks, maize cobs, brewer’s grains, seed meals, cotton hulls, Nevien AF M et al., 308 sugarcane bagasse and other agricultural residues high in lignocelluloses can be composted in a fermentation reactor(7).The use of organic manure is recommended to substitute the chemical fertilization(8). Raveendran et al.,(9) have found that addition of cow and chicken manures at different application rates increased total nitrogen in the 0-5 cm layer. According to Mathew and Nair(10) the cattle manure applied alone or in combination with NPK fertilizers increased both available P and K in Indian rice soils. The importance of organic matter for agriculture in Egypt comes next to that of water. It is well-known fact that recycling organic waste materials for increasing agricultural production and reduces environmental pollution. So, the aim of this study is to evaluate the impacts of application of different compost types produced in Alexandria City on the soil and plant. MATERIAL AND METHODS Sandy soils and four types of compost were applied; Composted sewage sludge, Composted domestic solid waste, composted plant residues, and composted animal manure. The Tested plant was Wheat (Giza 75). pot experiments were carried out at lab. Wheat planting took place on Nov. 15th 2003 at rate of 10 seeds/plot and thinned later to 4 seedlings. The soil pots received phosphorusnitrogen-potassium fertilizers in the form of super-phosphate, ammonium sulfate and potassium sulfate at rates of 200, 120, 50 kg/ at the recommended doses. One week before cultivation, the soils were mixed thoroughly with compost types by rates 10, 20 and 30% for each type. The treatments were replicated 4 times in a completely randomized block design. Raw compost samples were chemically characterized before application according to WHO International Reference Center for Waste Disposal(11). Soil samples were collected and physically and chemically 309 Bull High Inst Public Health Vol.38 No. 2 [2008] analyzed according to methods of soil analysis(12) before and after the addition of different compost types with its different rates. The wheat plant samples were sampled after about 150 days from the planting date. Morphological Data including fresh, dry weight, and plant height were recorded. All the plant samples were dried and chemically analyzed according to Benton(13). RESULTS DISCUSSION 1Before application: • Characterization of the soils: Sandy soil had pH value (8.51), NH4-N values (0.023 ppm), available P (2.27 ppm), and organic matter (0.075%). Regarding the heavy metals content, it was characterized by a high content of microelements especially Fe and Zn


INTRODUCTION
Over the past 50 years, the disposal of urban wastes has become increasingly difficult problem (1) .Landfill has always been the most common disposal method and is likely to remain so, but when sites close to a city have been filled up additional expenditure is necessary to transport the wastes to more distant sites.
Thus, it has become more and more important to discover treatment methods which reduce the volume of wastes to be accommodated on scarce landfill sites (1) .
Composting can have permanent and farreaching effects on the quality of the Bull High Inst Public Health Vol.38 No. 2 [2008]   environment by removing large amounts of refuse from the waste stream, thereby reducing land filling and incineration of wastes (2) .
Haug (3) has described composting as the biological decomposition and stabilization of organic substrates, under conditions that allow development of thermophilic temperatures as a result of biologically produced heat, to produce a final product that is stable, free of pathogens and plant seeds, and can be beneficially applied to land.Composting is used also as a means of converting objectionable wastes, such as sewage sludge, garbage, organic trash, food processing wastes and farm manures into materials suitable for application to land (2) .
The most commonly composted materials include those which are familiar to most people.Kitchen vegetable scraps, utilization on land or disposal (4) .
Compost as managing organic wastes, possess a low risk to the environment assuming it is free of heavy metals or hazardous organic materials (5) ; improves soil fertility whether in backyard gardens or reclaimed strip-mine soils; its product furnishes the soil with many of the rare elements essential for plant growth; it retains moisture and increases biological life in the soil; stimulates the rate of root growth; and it has relatively higher content of nitrogen, phosphorus and organic matter (6) .
Wheat straw, corn stalks, maize cobs, brewer's grains, seed meals, cotton hulls, sugarcane bagasse and other agricultural residues high in lignocelluloses can be composted in a fermentation reactor (7) .The use of organic manure is recommended to substitute the chemical fertilization (8) .
Raveendran et al., (9) have found that addition of cow and chicken manures at different application rates increased total nitrogen in the 0-5 cm layer.
According to Mathew and Nair (10) the cattle manure applied alone or in combination with NPK fertilizers increased both available P and K in Indian rice soils.Waste Disposal (11) .Soil samples were collected and physically and chemically Bull High Inst Public Health Vol.38 No. 2 [2008]   analyzed according to methods of soil analysis (12) before and after the addition of different compost types with its different rates.The wheat plant samples were sampled after about 150 days from the planting date.Morphological Data including fresh, dry weight, and plant height were recorded.All the plant samples were dried and chemically analyzed according to Benton (13) .
Regarding the heavy metals content, it was characterized by a high content of microelements especially Fe and Zn content.

Characterization of the compost:
It was revealed that sewage sludge compost has the highest content of salinity (6.0 dS m -1 ), available P (16.29 ppm) and available N in the form of NH4 (0.237 ppm).
Also, it has a high content of heavy and microelements.On the other hand, plant residues compost show a lower content of available N in the form of NH4 (0.027 ppm) and microelements and heavy metals content.

2-After application:
• Impacts on the soil Characterization:

Soil pH
Generally, all different compost types with its different rates caused decrease in pH values as compared with control value for sandy soils.The reduction in pH agreed with Moreno et al., (14) who attributed the reduction in pH results at the end of the growing season to the root exudates, the release of NH4 + and the nitrification process which take place during the course of plants growing period.
Narwell (15) reported that the reduction in pH results may be due to the release of organic acids, hydrogen ion ,and the increase in CO2 as a result of the decomposition of organic matter.These results are in agreement with those obtained by Abou Bakr (16) who revealed that the soil treated with mature compost gives the lowest pH values.

Soil Salinity (EC)
The data revealed a relative increase in soil salinity as compared with control value (0.26 dS m -1 ) in all compost applications.The highest value was obtained with animal manure compost at the rate of 30% (1.94 dS m -1 ) as presented in table (6) and the lowest one was obtained with plant residues compost at the rate of 10% (0.28 dS m -1 ) as presented in table (4).
Dahdoh and Hassan (17) showed the same results where increasing compost application rate increased the EC results and attributed that to the releasing substances from compost treatment which may directly or indirectly raised soil EC due to the microbial decomposition.
Logan et al., (18) rendered the increasing in EC results to the combination of mineralization of composted organic matter (especially sewage sludge compost) and climatic effects.The obtained results revealed that there was an increase in soil soluble cations and anions, except Ca, Na, and HCO3 in some treatments and some rates.The increase in cation and anion concentrations may be due to their continuous release with the biodegradation of compost (17) .Abou El-Naga et al., (19) agreed with the results of the current study and added that further amounts of available nutrients are released from the decomposed organic materials.

Soil mineral nitrogen
All compost applications resulted in increasing NH4-N as compared with control value (212.5 ppm) at the different rates.
The highest value obtained at the rate of 10% of plant residues and at the rate of 30% of sewage sludge composts (630.0 ppm), as recorded in Tables (4 and 5), while the lowest one was at the rate of 10% of domestic solid wastes compost (262.5 ppm), Table Regarding NO2+NO3-N, the highest value was at the rate of 30% of domestic solid wastes compost (145.0 ppm) compared with control value (95.0 ppm), Table (3), while the lowest value was recorded in animal manure compost application (42.5 ppm) which is the same at the three rates of application and lower than the control value, as presented in Table (6) and shown in Fig. (1).
The obtained increased results are in compliance with several investigators (20,21) , who showed that the application of different organic materials increased the availability of soil macronutrients.The increased results are in agreement with Abou El-Naga et al. (19) , who stated that increasing organic manure addition increased nutrient availability in the soil due to further amounts of available nutrients released from the decomposed organic manure.

Soil organic matter
Application of plant residues, sewage sludge and animal manure composts increased soil organic matter with increasing application rates, reaching highest value (5.76%) at the rate of 30% of sewage sludge compost application (Table 5) compared with the control (1.09%).On the other hand, addition of plant residues compost caused the lowest value of soil organic matter at the rate of 10% (3.34%), but still higher than control value, as Also, Alaa El-Din (20) found that the application of different organic manures increased organic matter content of the soil.Sherif et al., (22) indicated that increasing sludge addition rates increased organic matter content.Abdel-Latif and Abdel-Fatah (23) , who found that the greatest value of Fe obtained in the soil treated with organic residues could be related to the higher Fe content and the lower pH values of such residues which play an important role in the extracted micronutrients.

Heavy metals and micronutrients content
They also indicated that the decrease in pH and/or the C/N ratio increase of organic residues increased the extractable Zn.
Sherif et al., (22) found that all measured elements, except Cu, Pb, and Cr increased after 120 days of cultivation.This may be due to the influence of dynamic soil microbial biomass that affects nutrient availability.
The obtained lower values of Cu in the present study are in agreement with those obtained by Logan et al. (18) , who stated that it was possibly due to organic matter binding as organic matter decomposed.The decreased values of Fe with increasing compost application may probably be due to the biodegradation of compost which resulted in organic acids having functional groups that can complex this element (24) or due to the release of CO2 which led to the formation of Fe2(CO3) (25) .
• Sewage sludge compost application produced a higher dry matter than animal manure application, so sludge was slightly more effective than the manure compost, as referred by Bar Tal et al. (27) Engball et al., (28) have substantiated the effect of manure on increasing crop dry matter due to the multifold functions of organic materials such as soil structure stabilizer, nutrient storage basin, and buffering agent for soil chemical reactions.
Increased plant dry weight by sewage sludge compost compared to the control probably has been attributed to the release of N and P by mineralization.Sewage sludge compost application resulted in increased plant growth which agreed with Arisha and Abd El-Bary (29) , who revealed a significant increase in plant growth parameters of spinach and pea due to sewage sludge addition compared to control.
Such increase may be induced by higher concentrations of organic matter which, in turn, increases the microbial activity.
Moreover, adding sewage sludge increases organic matter in soil which, in turn, increases the proportion of chelation of Mn, Zn, and Cu in the soil to 50, 88, and 98%, respectively.as presented in Table (7).Fe content reached the lowest value with the application of plant residues compost at the rate of 30% (100.32 ppm), as detected in Table (7).In case of Mn content, the lowest value was obtained with the application of animal manure compost at the rate of 10% (22.07 ppm), as presented in Table (8).Cu content had its lowest value with plant residues compost at the rate of 10% (5.50 ppm), as presented in Table (7), and shown in Fig. (5).

Total macronutrients content (NPK)
It is clear that the beneficial effect of organic amendments on lowering soil pH values and, consequently, increasing the availability of Fe, Mn, and Zn, beside the higher initial content of such nutrient in the applied organic wastes (31) .Sherif et al., (22) also rendered Fe concentration decrease to the formation of complexes with organic matter which increased with increasing organic waste rates.

CONCLUSION AND RECOMMENDATIONS
Application of different types of compost to sandy soil cultivated with wheat plant increased soil salinity (EC), organic matter • Application of domestic solid wastes could be used at the range of 10 and 20% for sandy soil.
• Plant residues compost could be applied on sandy soil, at the rate of 10% only for cultivation of all crops.
• Application of animal manure compost could be applied at the range of 20-30% in case of sandy soil for all crops.
activities.Most of these materials, with the exception of the most recalcitrant woods and leaves, are easily compostable in the personal backyard compost pile.On an industrial level, many communities are investigating roadside pickup, chipping of materials, and large-scale composting of green wastes in a municipal setting.Composting of biosolids or animal manures is a means of reduction or stabilization of wastes prior to Sherif et al.(22), also, found that the fraction of Cu added which was extracted with DTPA, was smaller than the extractability fraction of the other metals.This may be due to strong tendency of Cu to form complexes with various organic legends.

•
, manganese (Mn), zinc (Zn), copper (Cu), chromium (Cr), and lead (Pb) contents and decreased pH and available phosphorus.As the soil treated with different compost types were enriched with macro and micronutrients, the fresh plants and ovendried weights of the plants of treated soil were higher than those of plants of untreated control soil.It is clear that sewage sludge and domestic solid wastes composts application indicated a highest plant yield among other compost types.So the study recommended the following: Application of sewage sludge compost must be applied under special control (application with lower rate and to certain plants; e.g., trees and other uneaten crops).

Figure ( 1 )Figure ( 4 )Figure ( 5 )
Figure (1): Available nitrogen and phosphorus concentrations (ppm) in sandy soil treated with different types of compost after wheat growing season.