A laboratory experiment was carried out to evaluate the manurial value of
different composts, produced by different technological methods, by measuring their
effects on some chemical and biological changes ir, newly reclaimed sandy soil.
These changes included: pH, organic carbon, total nitrogen and available-p, as well
as, the C02 evolution and enzymatic activities of invertase, phosphatase and
dehydrogenase. The soil samples were taken periodically (initially and after 2, 4, 8
and 12 weeks of added composts. The obtained results showed that amending the soil with the different types
of composts prepared by different additives slightly decrease the soil pH. The organic
carbon and total nitrogen increased in treated soil due to the higher C and N content
of the added composts. The CIN ratio narrowed in all treatments as a result of organic
carbon mineralization and the slightly increasing of total nitrogen in soil. Addition of
compost also increased the available phosphorus as a result of organo-phosphorus
compounds mineralization. Generally, the composts added in soil, increased the C02 evolved as a result
of stimulation of micro organisms in soil and induced the enzymes studied, improving
their activities in soil, especially, in the organic accelerated composts followed by the
chemical accelerated one.