[Biological fertility and its dynamics of degraded soil in Tibet Plateau].
In a three-year field trial, this paper studied the dynamics of biological fertility of degraded cultivated mountain shrubby steppe soil in the lower reaches of Lisa River as affected by fertilization. The results showed that under non-fertilized condition, the organic matter (OM) content in soil surface layer declined slightly, but after fertilization, the OM in this layer accumulated with a relatively high rate, humus structure improved obviously, soil bacteria had a significant multiplication, while soil microbial community was still in unharmonious state. With the increasing application rate of organic manure or chemical fertilizers, the OM content in 0 to approximately 30 cm and 30 to approximately 60 cm soil layers showed a significant increasing trend, with an annual increment being 1.35 and 0.67 g x kg(-1), respectively, and the ratio of humus carbon (C) to organic C and of humic acid C to humus C was also increased. Fertilization had a significant promotion effect on the multiplication and activity of soil bacteria. There was a significant positive correlation between the numbers of bacteria and OM content in 2 to approximately 30 cm (r = 0.7194 * *) and 30 to approximately 60 (r = 0.6042*) cm soil layers, while soil fungi and actinomycetes were not affected by fertilization. The numbers of azotobacter and cellulose-decomposing bacteria in different soil layers were lower in most fertilization treatments than in the control, and azotobacter in soil surface layer had a negative correlation with cellulose-decomposing bacteria (r = -0.4799).
Qian
Cheng
C
College of Agricultural and Animal Husbandry, Tibet University, Linzhi 860000, China. qianc21@sohu.com
Peng
Yuelin
Y
Jia
Junyan
J
Wei
Na
N
D000531:Altitude; D000818:Animals; D001395:Azotobacter / Q000254:growth & development; D005308:Fertilizers; D006812:Humic Substances / Q000032:analysis; D008372:Manure; D009930:Organic Chemicals / Q000032:analysis*; D012987:Soil / Q000032:analysis*; D012988:Soil Microbiology; D018609:Tibet
D005308:Fertilizers; D006812:Humic Substances; D008372:Manure; D009930:Organic Chemicals; D012987:Soil