[Effect of fertilization on soil enzymes and microbes in Larix gemlinii plantations]

One year-old second generation stand and 14 year- and 34 year-old first generation stands in larch plantations were studied at the Maoershan Mt. Experimental Forest Farm. The forestland of these three stands was treated with various fertilizations. The results showed that fertilization could promote or restrain soil enzyme activity and microbial amount with different degrees, and its effect on soil physiological activity was more apparent. The effect of the same fertilization treatments on soil enzyme activity and microbial amount was different at different development stages of the stands. For one year-old stand, the best fertilization scheme was treatment 9, its soil enzyme activities (catalase, proteinase, polyphenoloxidase, urease, and saccharase), total microbial amount, and amount of bacteria, actinomyces and fungus being increased by 413.49%, 22.10%, 20.56%, 220.00%, 49.46%, 238.88%, 247.24%, 106.70%, and 366.67%, respectively, as compared with the control. For 34 year-old stand, the best fertilization scheme was treatment 5, its soil enzyme activities (catalase, proteinase, polyphenoloxidase, urease, and saccharase), total microbial amount, and amount of bacteria and fungus was increased by 30.44%, 16.91%, 0.22%, 43.06%, 124.18%, 119.92%, 87.66%, and 17.57%, respectively in rhizosphere soil, and by 24.55%, 77.01%, 168.62%, 251.85%, 183.33%, 250.0%, 38.24% and 128.57%, respectively in non-rhizosphere soil. For 14 year-old young stand, it needed a proper amount of nitrogen fertilizer and organic mineral fertilizers, and the better fertilization schemes were treatments 2 and 9. The soil enzyme activities (catalase, proteinase, and urease) in treatment 2 was increased by 44.39%, 94.83%, and 4.62%, respectively in rhizosphere soil, and by 13.98%, 10.70% and 129.76%, respectively in non-rhizosphere soil. Total soil microbial amount and the amount of bacteria and fungus in treatment 9 was increased by 176.49%, 266.63%, and 198.04%, respectively in rhizosphere soil, and by 275.56%, 66.67% and 143.75%, respectively in non-rhizosphere soil.