07 Feb 2013

Regional Nutrient Budgets for Australia.

Summary of a presentation made at the ANZ Soils Conference.

Soil nutrient budgets of Australian natural resource management regions

The 2001 Australian Natural Resource Audit took account to the nutrient balances for different regions in Australia, based on data from 1994 to 1996. The methods used in that audit have been repeated for the years 2007-08 and 2009-10 using production data from each natural resource management region, fertilizer inputs from farm surveys, and expected nutrient densities.

The amounts of N, P, K and S applied as fertilisers and removed as agricultural commodities were calculated using ABS data for 2007-8 and 2009-10 for all Australian NRM regions. Graphics here are for 2009/2010.

The mass of P in commodities was 43% and 50% of mass applied in 2007-8 and 2009-10 (net input of 190 kt P and 170 kt P) nationally. Regions with (commodity P)/(fertiliser P) < 0.3 and > 10 kt P net input in both years were Murray, Murrumbidgee, Lachlan, and Glenelg Hopkins.

kg P/ha (Pin-Pout) per hectare of agricultural land in 2009-10.

Nationally, the mass of K in commodities was 2.5 and 3.1 times mass applied in 2007-8 and 2009-10 (net export of 196 kt P and 256 kt P). Regions with > 10 kt K net export and (commodity K)/(fertiliser K) >10 in both years were Wimmera, and Northern and Yorke.

kg K/ha (Kin-Kout) per hectare of agricultural land in 2009-10.

The mass of S removed in commodities was 49% and 62% of the mass applied in 2007-8 and 2009-10 (net export of 91 kt S and 62 kt S) nationally. Strong net addition of S in both survey years occurred in South-East (SA), South-West (WA) and Glenelg Hopkins.

kg S/ha (Sin-Sout) per hectare of agricultural land in 2009-10.

Nitrogen balance depends on the method used to calculate biological nitrogen fixation. Simply using fertiliser amounts (as below), regions with strong net input of N were Port Phillip and Westernport, West Gippsland, Hawkesbury-Nepean, Wet Tropics, and Condamine.

kg N/ha (fertilizer Nin-Nout) per hectare of agricultural land in 2007-08 (left) and 2009-10 (right).

These balances will be contrasted against the data from 2001 and used to make assessments of land management practices. A final report will contrast the two audit values by Natural Resource Management Region and implications for nutrient management research and policy will be discussed.

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