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Long term trends in fertility of soils under continuous cultivation and cereal cropping in southern Queensland .VI. Loss of total nitrogen from different particle size and density fractions

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Dalal, R.C. and Mayer, R. J. (1987) Long term trends in fertility of soils under continuous cultivation and cereal cropping in southern Queensland .VI. Loss of total nitrogen from different particle size and density fractions. Soil Research, 25 (1). pp. 83-93.

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Article Link(s): https://doi.org/10.1071/SR9870083

Publisher URL: https://www.publish.csiro.au/paper/SR9870083

Abstract

The dynamics of total N in particle-size and density fractions of six major soils which have been used for cereal cropping for 20-70 years were studied in order to identify the labile organic matter fractions in soil. For virgin soils, no single particle-size was consistently enriched in N as compared with the whole soil. The clay fraction contained the largest proportion (53% overall) of total N. Silt-size and sand-size N fractions accounted for 26% and 21% of total N, respectively. Upon cultivation, the sand-size fraction lost most of its N (as much as 89% in Langlands-Logie soil). However, N losses also occurred from silt-size and clay-size fractions in most soils. Changes in C : N ratios of different particle-size fractions upon cultivation were not consistent in all soils, possibly because of the transfer of organic C and N among these fractions. Therefore, the separation of labile organic matter fractions from the whole soil based upon particle-size may not be successful in all soils. On the other hand, the density fractionation of soil into a light fraction (<2 Mg m-3) containing relatively labile organic matter (76-96% lost upon cultivation) and a heavy fraction (>2 Mg m-3) containing less labile organic matter appears to be more successful in most soils. It is suggested that the cultural practices that enhance the amount of light fraction would increase the rate of nutrient cycling through microbial biomass and may increase the overall availability of nutrients in soil.

Item Type:Article
Business groups:Crop and Food Science, Animal Science
Additional Information:Reproduced with permission from © CSIRO Publishing. Access to published version is available via Publisher’s website.
Subjects:Agriculture > Agriculture (General) > Soils. Soil science > Soil and crops. Soil-plant relationships. Soil productivity
Agriculture > Agriculture (General) > Methods and systems of culture. Cropping systems
Agriculture > Agriculture (General) > Fertilisers
Plant culture > Field crops > Grain. Cereals
Plant culture > Field crops > Wheat
Agriculture > By region or country > Australia > Queensland
Deposited On:20 Jan 2022 04:10
Last Modified:28 Feb 2022 20:36

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