The link between soil microbial biomass phosphorus and movement of phosphorus to watercourses
Lead Research Organisation:
Rothamsted Research
Department Name: Sustainable Soils and Grassland Systems
Abstract
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Technical Summary
Our approach is to investigate soil microbial P dynamics, the relationships between these processes and their individual risks of causing P loss from soil to water through microbial processes. The project is therefore designed to take a mechanistic approach to confirm the interaction of microbial P and hydrology on P movement to watercourses. We will investigate interactions in two contrasting systems, grassland, which has continuous plant cover and arable, where there are extended periods of sparse, or absent, plant cover. We will do this at a range of scales, firstly on a microscale in a series of microcosms representing the two systems and subjected to a range of hydrological stresses (ie. wetting & drying/rewetting or flooding). The small scale of these studies will enable us to utilise radio- (33-P) isotope tracers to link biomass P dynamics with P loss to watercourses. Secondly, on a larger scale, isolated soil monoliths (1 x 1 x 1m) of the two systems will be established and subjected to hydrological events simulating natural rainfall, including storms. Continuous on-line monitoring of microbial activity (by measuring carbon dioxide evolution from respiration) and determination of P in leachates will allow us to confirm the link between microbial activity and P transfer to water, and the importance of organic matter incorporation into the soils. Thirdly, the findings from the smaller scale studies will be verified at a larger, field scale using the unique facilities of IGER¿s Rowden Research Platform with its 1 ha lysimeters, and the long-term Broadbalk plants at Rothamsted. (Joint with BB/C505059/1).
Organisations
Publications
Blackwell M
(2009)
Significance of Root-Attached Soil and Soil Preparation for Microbial Biomass Phosphorus Measurement
in Soil Science Society of America Journal
Blackwell M
(2010)
Advances in Agronomy v106
Blackwell M
(2009)
Effects of soil drying and rate of re-wetting on concentrations and forms of phosphorus in leachate
in Biology and Fertility of Soils
Dixon ER
(2010)
Measurement at the field scale of soil delta13C and delta15N under improved grassland.
in Rapid communications in mass spectrometry : RCM
Gordon H
(2008)
Drying and rewetting effects on soil microbial community composition and nutrient leaching
in Soil Biology and Biochemistry
Description | The discovery can be summarised in 4 headings: Seasonal biomass fluctuations: There was a significant seasonal dynamic in the microbial biomass in grazed grasslands. However, there were no significant changes in cut grassland, arable or fallow soils. After a period of drying, there was a decrease in microbial biomass associated with elevated concentrations of P in leachate on rewetting, implying a relationship between the two. Hydrological events: The rate at which dried soil is rewetted influences the concentration of P in leachate and thus water quality. This suggests that changes in patterns of rainfall predicted by climate change scenarios could significantly affect the quantities of P leached. Rhizosphere effects: Soil microbial biomass-P is concentrated around the roots in the rhizosphere soil compared with the bulk soil, highlighting this as the biological active area and potentially primes P leaching. Thus there is a strong need to review the conventional soil preparation procedures currently used. Organic matter incorporation and waterlogging: Hydrological stress had a greater impact on biomass concentrations than substrate incorporation, but substrate type had a greater impact on water-extractable P. However, large concentrations of water-extractable P following biomass death and lysis were observed during air-drying in a laboratory experiment. |
Exploitation Route | The work is of value to : 1. Help optimise the use of phosphorus fertlizer for food production and to; 2. Help reduce the transfer of fertilizer phosphorus from soils to water |
Sectors | Agriculture, Food and Drink,Chemicals,Education |