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Controlling soil water content in fertiliser dissolution experiments
journal contribution
posted on 1999-09-01, 00:00 authored by K Barlow, David HalliwellDavid Halliwell, D NashPhosphorus lost in runoff from agricultural land leads to the enrichment of surface waters and contributes to algal blooms. Fertilisers are one source of this P. To compare the water available P of different fertiliser formulations in the laboratory it is necessary to control environmental conditions, temperature, relative humidity and soil water content, prior to simulating rainfall. Two chambers were designed in which relative humidity and soil water content were controlled using salt solutions. An initial design comprising a sealed chamber with three layers of soil samples over a salt bath was found to be inferior to a single layer design. The changes in water content of soil samples were used to test the single layer chamber in a constant temperature environment (15°C) using a saturated KCl solution (90% relative humidity). Based on the final soil water content of the samples, the spatial variation within the chamber was within tolerable limits. The single layer chamber was used for a simulation experiment comparing the water available P of two commercial fertilisers. Using a saturated resorcinol solution (95% relative humidity) soil samples were equilibrated at 15°C for 21 days, fertiliser added, and the water available P measured up to 600 h after fertiliser application. The results indicate that the amount of water available P was related to the fertiliser compound and exponentially related to the time since fertiliser application. It was concluded that the single layer chamber is suitable for controlling relative humidity and soil water content in trials such as these where the water available P of fertilisers are being compared.
History
Journal
Nutrient Cycling in AgroecosystemsVolume
55Issue
1Pagination
7 - 14Publisher
Springer NetherlandsLocation
Dordrecht, The NetherlandsPublisher DOI
ISSN
1385-1314Language
engPublication classification
C1.1 Refereed article in a scholarly journalCopyright notice
1999, Kluwer Academic PublishersUsage metrics
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