Table 4. Uncertainty analyses of the retention coefficient using different combinations of δ¹³C values (‰) for maize and wheat.

	δ13C		Retention coefficient
	Maize	Wheat	Maize	Wheat	Maize: Wheat
Reference	−13	−27	0.112	0.244	0.46
S1	−13	−29	0.136	0.214	0.64
S2	−13	−25	0.080	0.285	0.28
S3	−11	−27	0.098	0.259	0.38
S4	−15	−27	0.130	0.224	0.58