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The measurement of mineralisation in field soils - ADAS part - NT1511

Improvements in methods for predicting the rate and timescale of N mineralization are essential for improving N fertiliser use recommendation systems. When modelling or estimating N mineralization, it is perceived to be more meaningful to concentrate on gross mineralization and immobilisation and derive net mineralization from these; however, simple techniques for measuring gross mineralization for advisory purposes are not yet available, while several techniques for net mineralization have been developed. This study will aim to test a range of simple field and laboratory-based methods for measuring net mineralization and one technique for measuring gross mineralisation (15N pool dilution). Relationships between the various methods will be examined, especially to see whether any of the measurements/predictions of net mineralization are related in a predictable way to measurements of gross mineralization. Several sites representing the major soil types (clay, loam and sand) will be subjected to the 15N pool dilution technique and to some or all of the following net mineralization techniques: in situ core incubation; laboratory incubation under both aerobic and anaerobic conditions; extraction of soluble organic matter with hot KCl; and uptake of N by grass given no fertiliser. Data provided by these methods will be used to validate models on which N advice systems will be based and to supplement advice given by advisory schemes based on models currently under development. Results of the study will be communicated in a variety of publications. The study will improve understanding of the key processes of mineralization and immobilisation and will have important implications for studies on nitrous oxide production, total N losses and soil microbial studies.
Time-Scale and Cost
From: 1995

To: 1998

Cost: £147,170
Contractor / Funded Organisations
Fields of Study
Fertilisers and Nitrate Pollution