Efficiency of resource use

The yield and fertilizer use data can be used to estimate the efficiency of various fertilizer strategies in these types of farming systems. The table below provides estimates of the four common nutrient use efficiencies (Dobermann 2007). Nitrogen recoveries almost tripled where P was added, and similarly, P recoveries increased greatly where N was added. Irrespective of the indicator used, the interaction of N and P is clear, with improved recoveries or higher productivity where nutrients are supplied together.

The effect of N and P on nitrogen and phosphorus use efficiency indicators partial factor productivity (PFP), partial nutrient balance (PNB), agronomic efficiency (AE) and recovery efficiency in grain (REgr) from a long term fertilizer experiment in southeastern Australia.

N rate kg/ha	P rate kg/ha	Efficiency indicator
		PFP kg/kgN	PNB kgN/kgN	AE Δkg/kgN	REgr ΔkgN/kgN
20	0	85	1.97	5	0.14
80	0	22	0.56	2	0.11
20	18	115	2.60	16	0.36
80	18	31	0.75	6	0.29
N rate kg/ha	P rate kg/ha	PFP kg/kgP	PNB kgP/kgP	AE Δkg/kgP	REgr ΔkgP/kgP
0	9	162	0.61	31	0.13
0	18	83	0.32	18	0.02
80	9	201	0.73	57	0.21
80	18	109	0.40	37	0.14