Table 4.

Inter-annual variability in maize yield (2005–11) under inoculation with P. bilaiae, in the large plot trials. Yield increase (%) is for inoculated crop relative to control (not inoculated)

Year	Yield (t/ha ± s.e.)	Range	Yield increase (% ±s.e.)	95% CI % increase*	Mean yield deviation (C† v. I‡) (t/ha ± s.e.)	Z-test (C† v. I‡)
2005	10·4 ± 0·33	2·5–14·4	3·5 ± 0·65	2·1–4·8	0·35 ± 0·071	<0·001
2006	10·3 ± 0·20	5·9–14·5	2·3 ± 0·47	1·4–3	0·22 ± 0·048	<0·001
2007	8·8 ± 0·29	5·1–14·1	5·2 ± 0·83	3·5–6·9	0·42 ± 0·066	<0·001
2008	9·8 ± 0·44	4·6–13·1	4·3 ± 0·63	3·0–5·6	0·38 ± 0·053	<0·001
2009	11·1 ± 0·32	5·7–15·4	3·4 ± 0·81	1·8–5·1	0·38 ± 0·083	<0·001
2010	10·1 ± 0·40	4·9–15·6	3·3 ± 0·83	1·6–4·9	0·32 ± 0·082	<0·001
2011	9·4 ± 0·38	5·8–14·3	4·2 ± 0·99	2·2–6·3	0·37 ± 0·087	<0·001

^*Confidence interval.

^†Control.

^‡Inoculated.