Effect of long-term fertilisation on enzyme activities and microbial community composition in the rice rhizosphere
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Abstract
Mineral fertilisers differ in changing soil properties, and revealing how the rhizosphere and non-rhizosphere respond could provide a robust assessment of fertiliser regimes. Rhizosphere and non-rhizosphere soils were sampled from five fertilisation treatments in a long-term (24 year) experiment. Enzyme activities and total phospholipid fatty acids (PLFA) content in the rhizosphere soil were 85.8% and 51.3% higher than in the non-rhizosphere soil, respectively. Fertilisation increased enzyme activities, especially the N-cycling enzyme β-1,4-N-acetylglucosaminidase in NP fertilised soil (1.5 and 2.5 times for rhizosphere and non rhizosphere soil, respectively). The PLFA composition indicated that fungi cominated in the rhizosphere fertilised with P, whereas bacteria were more common in the non-rhizosphere soil. The PLFA contents and enzyme activities in the rhizosphere of P-fertilised plants were lower than those in the non-rhizosphere soil because P availability was lower in the rhizosphere. The redundancy analysis showed that the microbial community in the rhizosphere soil was different from that of the non-rhizosphere soil, mainly because there were differences in the 15:1ω6c and 16:0. Long-term (24 year) fertilisation strongly increased nutrient contents, and microbial biomass and activity in paddy soil. It is advisable to apply P fertiliser in the root zone to increase fertiliser use efficiency.