The experiment was carried out to evaluate effects of covering wheat straw in apple orchard and apricot orchard on soil humus composition

microflora and soil enzyme activities. The results showed that after covering wheat straw

the contents of soil humus

humic acid(HA) and the rate of HA to fulvic acid(FA) were increased effectively; Contents of heavy fraction

loosely combined

tightly combined humus were also increased

and especially

the relative rate of loosely combined humus compared with heavy fraction humus and tightly combined humus was also increased obviously. The amounts of bacterium

antinomyces

ammonifying bacteria and cellulose-utilizing bacteria were increased

the nitrobacteria amount was decreased; the activities of polyhenol oxidase

sucrase

alkaline phosphatase

urease and cellulose were increased

but it didnt take much effect on the activity of catalase.