Nutrient Balances for Australian Natural Resource Management Zones

Estimating nutrient inputs and removals in Australian agricultural regions.


23 Jan 2013

Phosphorus Balance by Australian NRM zone

Phosphorus balances in Australian NRM regions

Robert Edis1 and Robert Norton2

1Melbourne School of Land and Environment, The University of Melbourne, Parkville, Victoria, 3010, Australia.; 2International Plant Nutrition Institute, 54 Florence St, Horsham, Victoria, 3400, Australia

Introduction and approach
Phosphorus (P) inputs and outputs for Australian NRM regions were calculated using Australian Bureau of Statistics data for land management and agricultural commodities, 2007-8 and 2009-10 (Australian Bureau of Statistics 2009a,b; 2011a,b) in order to identify areas in which strong imbalance occurs. Estimates of regional and national P fertiliser use efficiency were also made using these and earlier surveys. Widely accepted P concentrations in commodities and chemical fertilisers were used. However, the contribution to P balance from animal manure applications has greater uncertainty due to several variables such as the types and sources of manure and feed. Data sources, discrepancies between survey and industry data, assumptions and reliability will be explored.

Nationally, the mass of P in commodities (Pout) was estimated to be 43% and 50% of that applied (Pin) in 2007-8 and 2009-10 (Table 1), resulting in net inputs of 190 kt P and 170 kt P. Regions with Pout/Pin <0.3 and net input >10 kt P in both years were Murray, Murrumbidgee, Lachlan, and Glenelg Hopkins. Fourteen out of 53 agricultural NRM regions had imbalances [(Pin-Pout)/(area used for agriculture)] of > 3 kg/ha, being (with 2009-10 balance in kg P/ha): Glenelg Hopkins (9.2); NW Tas (6.7); Kangaroo Island (5.4); Mallee (4.8); West Gippsland (4.5); Port Phillip and Western Port (4.3); Goulburn Broken (4.1); WA South Coast (3.9); Murray (3.4); North Tas (3.4); Northern and Yorke (3.1); Vic North Central (3.1); Adelaide and Lofty Ranges (3.1), and Murrumbidgee (3.0).

Table 1 State and national P budget estimates, 2009-10.
Pin (kt) ABS data [FIFA data 2010]1Pout (kt)Pout/PinBalance kg P/ha agricultural land
Qld14 [19]292.0 (1.8)2-0.1
NSW94 [68]370.40 (0.30)1.0
Vic85 [87]320.37 (0.33)4.1
Tas7.6 [12]2.30.30 (0.29)3.2
SA58 [59]240.42 (0.29)0.7
WA82 [113]430.52 (0.40)0.4
NT0.1 [0.3]2.828 (14)0.0
Australia341 [359]1700.50 (0.43)0.4
1Fertiliser Industry Federation Australia sales data presented for comparison 2estimate of Pout/Pin for 2007-2008
The poor recovery of applied P in commodities from agriculturally intense regions, particularly in Victoria and Tasmania over these survey years, as well as those of the NLWRA audit, indicate low long-term P-use efficiencies. Implications for nutrient management research and policy will be discussed, considering agricultural industries, climate, soil types, and water resources.
Australian Bureau of Statistics (2009a) Land Management and Farming in Australia, 2007-08 (46270DO001_200708)
Australian Bureau of Statistics (2009b) Agricultural Commodities, Australia, 2007-08 (71210DO001_200708)
Australian Bureau of Statistics (2011a) Land Management and Farming in Australia, 2009-10 (46270DO006_200910)
Australian Bureau of Statistics (2011b) Agricultural Commodities, Australia, 2009-10 (71210DO001_200910)