Graeme Blair1, Nelly Blair2
1 Agronomy and Soil Science, University of New England, Armidale, NSW, 2350. email@example.com
2 Ourfing Partnership, 640 Boorolong Rd., Armidale, NSW, 2350
World fertiliser consumption has moved largely to high analysis, non-sulfur containing products which, in many situations, has led to sulfur (S) deficiency and consequently reduced nitrogen use efficiency (NUE). Calculations on data from field experiments conducted in China with rice and soybeans have been used to estimate the reduction in N2O emissions resulting from addition of S to mono-ammonium phosphate (MAP). Balanced nutrition using MAP+S in two experiments in China resulted in an increase in NUE of 9.4% in flooded rice and 12.6% in soybeans. Assuming a loss of 20% of fertiliser N as N2O in flooded rice and 10% in soybeans the increased N usage by the crop results in a potential N2O saving of 3.9 and 1.2 kg N2O/ha, respectively, in the two crops.
Balanced fertilisation and crop residue management can also be used to abate agricultural CO2 emissions. Using data from an extensive field research program, it is estimated that addition of S to MAP in a temperate climate can result in an incremental CO2 sequestration in excess of 8 t CO2/t applied S and this can be increased a further 4% if crop residues are retained. The increased crop residue produced, and retained, as a result of balanced fertilisation resulted in an estimated incremental CO2 sequestration of 3.7 t CO2/t S applied in a tropical crop production system to 5.5 t CO2/t S applied in a temperate system.