Phosphorus response and efficiency of four adventive annual clovers grown in a New Zealand high country soil under glasshouse conditions

Figures & data

Table 1 . Initial fertility status of a high country Allophanic Brown soil used in the glasshouse experiment. Topsoil sample (0–75 mm) was collected from a mid-altitude (740 m) central South Island, New Zealand high country site in June 2008.

Soil properties
pH	5.2
Olsen P	11 mg kg^−1
Sulphate S	4 mg kg^−1
CEC	20 cmolc kg^−1
Base Saturation	39.9%
Exchangeable Ca	5.7 cmolc kg^−1
Exchangeable Mg	1.59 cmolc kg^−1
Exchangeable K	0.53 cmolc kg^−1
Exchangeable Na	0.11 cmolc kg^−1
Total N	0.63% w/w
Total C	9.62% w/w
C/N Ratio	15
Mineralisable N	288 kg ha^−1
P Retention (ASC)	44%

Table 2 . Values of total accumulated shoot yield, P concentration and P uptake by six pasture legume species, grown under glasshouse conditions in a New Zealand high country soil supplied with increasing rates of P (eight levels of P; increasing from 0 to 2500 mg P kg⁻¹ soil) and Olsen P values of soil in which plants were grown.

Species		Mean shoot yield g DM/pot	Mean shoot P concentration % P	Mean shoot P uptake mg P/pot	Olsen P^1 mg kg^−1
T. glomeratum		1.31	0.41	5.3	82
T. arvense		3.37	0.40	14.1	77
T. subterraneum		4.40	0.59	24.1	81
T. dubium		1.44	0.55	8.1	64
T. striatum		0.81	0.46	3.8	79
T. repens		1.67	0.39	7.5	78
Grand mean		2.168	0.470	10.47	77
Species	LSD (5%)	0.173	0.059	1.43	4.3
P rate	0	1.26	0.33	4.3	11
	30	1.87	0.35	6.4	13
	60	1.79	0.36	6.1	16
	100	2.12	0.38	8.1	21
	250	2.57	0.46	10.9	46
	500	2.82	0.50	14.1	84
	1000	2.52	0.61	16.0	151
	2500	2.39	0.74	17.9	271
	LSD (5%)	0.199	0.068	1.65	4.9
P	Species	***	***	***	***
	P rate	***	***	***	***
	Sp×P Rate	***	***	***	***
^1Olsen P values at the completion of the experiment.
***Significant at P<0.001

Figure 1.  Total accumulated shoot dry matter (DM) yield response of pasture legume species—A, Trifolium glomeratum; B, T. arvense; C, T. subterraneum; D, T. dubium; E, T. striatum; and F, T. repens—to increasing levels of soil phosphorus (eight levels of P; ranging from 0 to 2500 mg P kg⁻¹ soil), grown in a New Zealand high country soil. Data are mean values ± SEM (n =4), with R ² and P values for fitted curve showing data trend.

Table 3 . Rate of P application and shoot P concentration at which 95% maximum yield was observed for the pasture legume species.

Species	Maximum yield g DM/pot	P Rate mg P kg^−1	Shoot P concentration %
T. glomeratum	1.9	500	0.44
T. arvense	4.3	250	0.38
T. subterraneum	6.3	500	0.61
T. dubium	1.7	2500	0.96
T. striatum	1.3	250	0.46
T. repens	2.6	500	0.47

Figure 2.  Comparison of shoot P concentration of pasture legume species—A, T. glomeratum; B, T. arvense; C, T. subterraneum; D, T. dubium; E, T. striatum; and F, T. repens—grown in a New Zealand high country soil supplied with increasing levels of soil phosphorus (eight levels of P; ranging from 0 to 2500 mg P kg⁻¹ soil). Data are mean values ± SEM (n =4), with R ² and P values for fitted curve showing data trend.

Figure 3.  Comparison of P-response efficiency of pasture legume species—A, T. glomeratum; B, T. arvense; C, T. subterraneum; D, T. dubium; E, T. striatum; and F, T. repens—grown in a New Zealand high country soil supplied with increasing levels of soil phosphorus (eight levels of P; ranging from 0 to 2500 mg P kg⁻¹ soil). Data are mean values ± SEM (n =4), with R ² and P values for fitted curve showing data trend.