الفهرس 
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Abstract
Sugarcane straw is considered one of the most important agricultural residues produced after harvesting the sugarcane crop in Upper Egypt. It is found in large quantities, as the resulting quantity ranges between 2.5 to 3 tons per feddan and it is contains a high nutritive values of organic carbon and organic matter. Therefore, it was found of interested to study the possibility of using sugarcane straw as an organic amendment, before and after composting, for improving soil properties. On addition, the resultant effect on wheat yield was in vestigated.
The results could be summarized as follows:
Part I
In this study, sugarcane straw was used to prepare different composts as organic fertilizers. These experiments aimed to conduct microbiological studies on the utilization of sugar cane straw and converting it into organic fertilizer in order to reduce environmental pollution and reduce the use of chemical fertilizers. Under Egyptian conditions.
1) Sugarcane straw was collected and chemically analyzed, based on the analysis, the sugarcane straw was chopped and heaps were made with the required specifications.
2) Moisture content:
Moisture content was determined every week for a better monitoring of the composting process at initial time the humidity was reached 60 to 65%, then decreased to 30 % at the final stage in all heaps. In some cases moisture content 60-65% is acceptable at the beginning of the composting process; then decreased to 30 % which inhibits the biological activity in the final product. This indicates the maturity of compost heaps.
3) Self-heating temperature:
During composting process, self-heating temperature was measured at different depths (20, 40 and 60 cm) of heaps. The temperature was registered daily during the first week then at every week till the end of composting (4 months).
The results revealed that self-heating temperature in all heaps under study increased to above 60 °C and reaching the maximum during the first month, then gradually decreased down 25-34 °C till the end of composting period. It was found that the maximum self-heating temperature recorded in all heaps seemed to be high in the depths of 60 cm as compared with 40 or 20 cm respectively.
A decrease in self-heating temperature with the disappearance of the smell of ammonia and the turning of the heaps to brown indicates the maturity of compost heaps. Generally, the self-heating temperatures was higher in compost of sugarcane straw with nitrogen compared with control (compost of sugarcane straw only).
4) Microbiological changes during composting process:
Counts of mesophilic and thermophilic bacteria and actinomycetes, spore formers and aerobic cellulose decomposers increased during composting process as compared with their initial counts.
5) Chemical changes during composting process:
Samples were taken at different period (0, 10th, 20th, 30th, 45th, 60th, 90th and 120th days) during composting process where chemical changes such as soluble nitrogen (Ammonium + nitrate), total nitrogen, organic matter and C/N ratio and pH were studied.
Results obtained were as followed:
• Organic fertilizers resulting after composting showed appreciable amounts of soluble nitrogen (NH4+ NO3), total nitrogen and organic carbon (OC) as compared with that before composting. The increase of nitrogen and organic matter was more noticeable in compost of sugarcane straw supplemented with nitrogen.
• C/N ratio decreased by composting reaching about 12.6:1 in compost of sugarcane straw with nitrogen and 13.23:1in sugarcane straw without nitrogen.
• The recorded pH values tended to decreased in all heaps and on 120th days being in the average of 6.5 in sugarcane straw without nitrogen and 6.7 in sugarcane straw with nitrogen at the end of the experiment.
Part II
Apot experiment was carried out to study the effect of sugarcane straw as it is, composted sugarcane straw composted without nitrogen, composted sugarcane straw with nitrogen on microbiological activity (counts of bacteria , actinomycetes, spore formers, aerobic cellulose decomposers , Azotobacter and Azospirillum) and chemical changes (soluble nitrogen, total nitrogen, organic carbon (OC) and C/N ratio ) in two types of soils (clay loam and sandy soils) during 90 days incubation period.
The results obtained were as follows:
• The numbers of all studied micro-organisms were much higher in clay loam soil than in sandy one.
• The application of any of the different treatments of sugarcane straw resulted in increasing numbers of bacteria, actinomycetes, spore formers, aerobic cellulose decomposers , Azotobacter and Azospirillum as compared with control (soil only).
• The application of sugarcane straw as it is, as well as composted sugarcane straw with or without nitrogen resulted in high amounts of soluble-N ( NH4-N+ No2-N+ No3-N), total-N and organic matter contents compared with control (soil only). These high amounts were more pronounced in clay loam soil than those in sandy one.
Part III
A field experiment in clay loam soil was undertaken to study the Effect of supplementation of 10 ton / fed. Sugarcane straw as it is as well as composted sugarcane straw with or without nitrogen, singly or in compination with NP, fertilizers (150 kg urea 46%N +100 kg superphosphate 15.5% p2o5 / fed.) on microbiological and chemical changes in the soil and on the yield of wheat (grains and straw).
Soil samples were taken at zero, 30, 60, 90,120 and150 days after sowing.
The results obtained were as follows:
• The numbers of bacteria, actinomycetes, aerobic cellulose decomposers, Azotobacter SP. and Azospirillum SP. were increased in all treatments compared with control (soil only).
• Soluble nitrogen and phosphorus content of treated soil were fluctuated depending on wheat plant need during its growth.
• Wheat yield was increased in all treatments as compared with control (soil only).
The highest yield resulted from soils treated with10 ton / fed.composted sugarcane straw with NP, fertilizers. This increase of yield was highly significant as compared with control (soil only).
Generally, the obtained results from the current study indicate that the application of compost prepared from sugarcane straw as it is with or without nitrogen improved soil biological activity, fertility and productivity. Thus, sugarcane straw can be used as a substitute for other organic manures for amending soils.