Agronomic phosphorus fertiliser value of animal manures is comparable to monoammonium phosphate for wheat production

Animal manures may be a sustainable alternative to rock phosphate-based fertilisers, provided they have similar agronomic phosphorus (P) fertiliser values. If higher application rates from manure are required to match crop yield responses to mineral P fertilisers, soil P can accumulate and P use efficiency of the farming system is reduced. This study investigated the P fertiliser value of various manures compared to monoammonium phosphate (MAP). A P dose-response experiment assessed the impact of cattle (CaM), chicken (ChM), and pig (PiM) manures compared to MAP on wheat growth (biomass, grain yield) and P uptake in an Arenosol. The effects of subsurface banding versus incorporation were also evaluated in an Arenosol and a Ferralsol, with post-harvest soil P fractions analysed in selected treatments. To achieve 95 % maximum grain yield, P rates required were in order PiM > CaM = MAP > ChM. The ChM treatment had poor growth at high manure application rates due to sodium toxicity. Mixed through the topsoil, CaM and PiM increased biomass (95 % of maximum) by 12.3 % and 9.9 % and grain yield (95 % of maximum) by 19.7 and 20.9 % relative to banded MAP. Subsurface banding enhanced P uptake in a high P-sorbing Ferralsol, while incorporation enhanced uptake in a low P-sorbing Arenosol. In the Ferralsol, more P was retained in the sodium bicarbonate extractable organic P (NaHCO₃-P o ) fraction with CaM and in the inorganic P (NaHCO₃-P i ) fraction with MAP. Cattle manure and PiM had comparable or greater P fertiliser value than MAP for wheat yields, with the application method likely impacting P availability. These findings demonstrate that certain manures can match or exceed the agronomic P fertiliser value of MAP in wheat production. • Animal manures match or exceed the phosphorus fertiliser value of mineral fertiliser. • Soil phosphorus dynamics linked to manure bioavailability and sorption capacity. • Wheat yield and phosphorus use efficiency improved with cattle and pig manure. • Application methods significantly impact phosphorus uptake across soil types.