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2470665 
Journal Article 
Liming and nitrogen fertilization affects phosphatase activities, microbial biomass and mycorrhizal colonisation in upland grassland 
Johnson, D; Leake, JR; Read, DJ 
2005 
1 
Plant and Soil
ISSN: 0032-079X
EISSN: 1573-5036 
SPRINGER 
DORDRECHT 
271 
1-2 
157-164 
WOS:000230397200014 
We have studied the effects of factorial combinations of lime and N additions on soil microbial biomass, respiration rates and phosphatase activity of an upland grassland. We also used an Agrostis capillaris seedling bioassay to assess the effect of the treatments on the activity of arbuscular-mycorrhizal (AM) fungi and root surface phosphatase enzymes and the concentrations of N and P in the bioassay plant shoots. In the F and H horizons, soil microbial biomass carbon (C-mic) decreased in response to the liming, while addition of lime and N together reduced basal respiration rates. In the Ah horizon, C-mic was unaffected by the treatments but basal respiration rates decreased in the plots receiving nitrogen. Soil phosphatase activity decreased only in the Ah horizon in plots receiving lime, either in combination with N or alone. The mass of root fwt. colonized by AM fungi increased in response to the treatments in the order nitrogen < lime < N plus lime. In contrast, root surface phosphatase activity decreased only in response to additions of nitrogen. A positive linear relationship was observed between root surface phosphatase activity and the P concentration of the plant shoots (R-2 = 28.7%, P = 0.004). The results demonstrate the sensitivity of both free-living heterotrophic microorganisms and symbiotic mycorrhizal fungi to short-term (2 years) applications of lime and N to long-term upland grassland, particularly in relation to the key P cycling activities undertaken by these organisms. 
arbuscular-mycorrhiza; improved grassland; microbial biomass; phosphatase