Mineralisation of carbon and plant uptake of phosphorus from microbially-derived organic matter in response to 19 years simulated nitrogen deposition

• Published in: Plant and soil 2010-01, Vol.326 (1/2), p.311-319
• Main Authors: Kritzler, Ully H., Johnson, David
• Format: Article
• Language: English
• Subjects: Acid soils; Agronomy. Soil science and plant productions; Animal, plant and microbial ecology; Biological and medical sciences; Biomedical and Life Sciences; Carbon; Chemical, physicochemical, biochemical and biological properties; Ecology; Fundamental and applied biological sciences. Psychology; General agronomy. Plant production; Grassland soils; Life Sciences; Mineralization; Nitrogen; Organic matter; Organic phosphorus; Organic soils; Phosphatases; Phosphorus; Physics, chemistry, biochemistry and biology of agricultural and forest soils; Plant biology; Plant Physiology; Plant Sciences; Plant species; Plants; Pollutant deposition; Regular Article; Soil air; Soil microbiology; Soil microorganisms; Soil organic matter; Soil pollution; Soil science; Soil Science & Conservation; Soil sciences; Soil-plant relationships. Soil fertility; Soil-plant relationships. Soil fertility. Fertilization. Amendments
• ISSN: 0032-079X; 1573-5036
• DOI: 10.1007/s11104-009-0009-y

Here we test the hypotheses that 19 years of simulated pollutant N deposition increases both losses of carbon (C) and the ability of plants to access P from organic material in upland heathland. The grass, Dactylis glomerata, and the dwarf shrub, Calluna vulgaris, were grown in soil containing microbial-derived organic matter labelled with 14C and 33P. We found that both soil and root-surface phosphatase activity increased significantly in response to N deposition. We also found a significant positive relationship between root-surface phosphatase activity and 33P uptake for Calluna, but a negative relationship for Dactylis. Efflux of 14C from the microbial-derived organic matter was strongly dependent on an interaction among plant presence, plant species and N deposition. Our results show that mineralisation of C and P, and subsequent plant uptake of P from organic sources is decoupled. In our experimental conditions, stimulation of P turnover coupled with subsequent plant uptake through upregulation of root phosphatases is little affected by N addition. However, our data indicate that root-surface phosphatases are likely to be more important for uptake of P derived from organic sources for Calluna than for Dactylis.