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Estimating mineralisation of organic nitrogen from biosolids and other organic wastes applied to soils in subtropical Australia

Pu, G. X. and Bell, M. and Barry, G. and Want, P. (2012) Estimating mineralisation of organic nitrogen from biosolids and other organic wastes applied to soils in subtropical Australia. Soil Research, 50 (4). pp. 91-104. ISSN 1838-675X

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Article Link(s): http://dx.doi.org/10.1071/sr11272

Abstract

One major benefit of land application of biosolids is to supply nitrogen (N) for agricultural crops, and understanding mineralisation processes is the key for better N-management strategies. Field studies were conducted to investigate the process of mineralisation of three biosolids products (aerobic, anaerobic, and thermally dried biosolids) incorporated into four different soils at rates of 7-90 wet t/ha in subtropical Queensland. Two of these studies also examined mineralisation rates of commonly used organic amendments (composts, manures, and sugarcane mill muds). Organic N in all biosolids products mineralised very rapidly under ambient conditions in subtropical Queensland, with rates much faster than from other common amendments. Biosolids mineralisation rates ranged from 30 to 80% of applied N during periods ranging from 3.5 to 18 months after biosolids application; these rates were much higher than those suggested in the biosolids land application guidelines established by the NSW EPA (15% for anaerobic and 25% for aerobic biosolids). There was no consistently significant difference in mineralisation rate between aerobic and anaerobic biosolids in our studies. When applied at similar rates of N addition, other organic amendments supplied much less N to the soil mineral N and plant N pools during the crop season. A significant proportion of the applied biosolids total N (up to 60%) was unaccounted for at the end of the observation period. High rates of N addition in calculated Nitrogen Limited Biosolids Application Rates (850-1250 kg N/ha) resulted in excessive accumulation of mineral N in the soil profile, which increases the environmental risks due to leaching, runoff, or gaseous N losses. Moreover, the rapid mineralisation of the biosolids organic N in these subtropical environments suggests that biosolids should be applied at lower rates than in temperate areas, and that care must be taken with the timing to maximise plant uptake and minimise possible leaching, runoff, or denitrification losses of mineralised N.

Item Type:Article
Business groups:Crop and Food Science
Additional Information:Pu, Guixin Bell, Mike Barry, Glenn Want, Peter
Subjects:Agriculture > Agriculture (General) > Soils. Soil science > Soil chemistry
Agriculture > Agriculture (General) > Soil conservation and protection
Deposited On:25 Feb 2014 03:55
Last Modified:08 Aug 2017 14:57

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