Table 2.

Root densities and wheat dry matter in response to K application; SD means the standard deviation; DM means dry matter; RDM means relative dry matter and R² is the coefficient obtained by fitting the Mitscherlich curve, where “—” means no R² obtained due to: a) the response in the fertilized treatment was unexpectedly below the controls, dry mass in the control soil is taken as the DM_max and b) a linear response was observed, dry mass of 120% of the highest K rate is taken as the DM_max; different letters mean significant difference observed at P ≤ 0.05.

Soil	Pot size	K rate (mg kg−1)				P (mg kg−1)	Root density (g m−3)	SD of root density	DMcontrol (g pot−1)	RDM of control soils (%)	DMmax (g pot−1)	DMmax predicted (g pot−1)	R2
		Control	K 1	K 2	K 3
KD	Small	0	50	150	300	300	169bcd	74	0.39bcd	75	0.59	0.53	0.64
LB		0	50	150	300	300	102abc	20	0.34abc	83	0.41	0.41	0.73
NK		0	50	150	300	300	49a	29	0.15a	39	0.39	0.39	1.00
QB		0	50	250	500	500	144bcd	73	0.28abc	38	0.77	0.73	0.92
QC		0	50	250	500	500	148cd	38	0.59d	68	0.86	0.86	1.00
QL		0	50	150	300	300	187d	57	0.32abc	49	0.75	0.65	0.79
QS		0	50	250	500	500	131bcd	51	0.48bcd	63	0.82	0.76	0.88
RF		0	50	150	300	300	179cd	84	0.46bcd	80	0.58	0.58	1.00
WN		0	50	150	300	300	86ab	19	0.22ab	67	0.33	0.32	0.96
KD	Large	0	50	150	300	300	18a	4	0.30 cd	100	0.30	0.30a	—
LB		0	50	150	300	300	26ab	3	0.25abc	100	0.25	0.25a	—
NK		0	50	150	300	300	15a	10	0.11a	41	0.28	0.27	0.93
QB		0	50	250	500	500	27ab	13	0.26c	55	0.49	0.48	0.99
QC		0	50	250	500	500	30c	8	0.42d	87	0.50	0.48	0.74
QL		0	50	150	300	300	15a	4	0.27c	86	0.34	0.32	0.61
QS		0	50	250	500	500	23ab	5	0.43d	70	0.51	0.61b	—
RF		0	50	150	300	300	18a	7	0.25bc	100	0.25	0.25a	—
WN		0	50	150	300	300	19a	5	0.13ab	59	0.24	0.22	0.92