Fate of applied biosolids nitrogen in a cut and remove forage system on an alluvial clay loam soil

Pu, Guixin, Bell, Mike, Barry, Glenn and Want, Peter (2008) Fate of applied biosolids nitrogen in a cut and remove forage system on an alluvial clay loam soil. Australian Journal of Soil Research, 46 8: 703-709. doi:10.1071/SR08127


Author Pu, Guixin
Bell, Mike
Barry, Glenn
Want, Peter
Title Fate of applied biosolids nitrogen in a cut and remove forage system on an alluvial clay loam soil
Journal name Australian Journal of Soil Research   Check publisher's open access policy
ISSN 0004-9573
1446-568X
Publication date 2008
Year available 2008
Sub-type Article (original research)
DOI 10.1071/SR08127
Open Access Status
Volume 46
Issue 8
Start page 703
End page 709
Total pages 7
Place of publication Collingwood, VIC Australia
Publisher C S I R O Publishing
Collection year 2009
Language eng
Subject 1111 Nutrition and Dietetics
2304 Environmental Chemistry
Abstract The fate of nitrogen (N) applied in biosolids was investigated in a forage production system on an alluvial clay loam soil in south-eastern Queensland, Australia. Biosolids were applied in October 2002 at rates of 6, 12, 36, and 54dryt/ha for aerobically digested biosolids (AE) and 8, 16, 48, and 72dryt/ha for anaerobically digested biosolids (AN). Rates were based on multiples of the Nitrogen Limited Biosolids Application rate (0.5, 1, 3, and 4.5NLBAR) for each type of biosolid. The experiment included an unfertilised control and a fertilised control that received multiple applications of synthetic fertiliser. Forage sorghum was planted 1 week after biosolids application and harvested 4 times between December 2002 and May 2003. Dry matter production was significantly greater from the biosolids-treated plots (21-27t/ha) than from the unfertilised (16t/ha) and fertilised (18t/ha) controls. The harvested plant material removed an extra 148-488kg N from the biosolids-treated plots. Partial N budgets were calculated for the 1NLBAR and 4.5NLBAR treatments for each biosolids type at the end of the crop season. Crop removal only accounted for 25-33% of the applied N in the 1NLBAR treatments and as low as 8-15% with 4.5NLBAR. Residual biosolids N was predominantly in the form of organic N (38-51% of applied biosolids N), although there was also a significant proportion (10-23%) as NO3-N, predominantly in the top 0.90m of the soil profile. From 12 to 29% of applied N was unaccounted for, and presumed to be lost as gaseous nitrogen and/or ammonia, as a consequence of volatilisation or denitrification, respectively. In-season mineralisation of organic N in biosolids was 43-59% of the applied organic N, which was much greater than the 15% (AN)-25% (AE) expected, based on current NLBAR calculation methods. Excessive biosolids application produced little additional biomass but led to high soil mineral N concentrations that were vulnerable to multiple loss pathways. Queensland Guidelines need to account for higher rates of mineralisation and losses via denitrification and volatilisation and should therefore encourage lower application rates to achieve optimal plant growth and minimise the potential for detrimental impacts on the environment.
Keyword Ammonia volatilisation
Denitrification
Leaching
Mineralisation
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Non-UQ

Document type: Journal Article
Sub-type: Article (original research)
Collection: Queensland Alliance for Agriculture and Food Innovation
 
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