Table 9.
Regression statistics (for all sites) and parameter coefficients (for the phosphorus effect: with + Pa; without -P) for the relationship between relative yield (RY) and soil pH described by Eq. 1 for several different arable crops from the long-term liming experiment at Rothamsted and Woburn 1962–1996.
| Crop | Site | Fert. P level | P value | R2 | A (± SE) | B (± SE) | D (± SE) |
|---|---|---|---|---|---|---|---|
| Spring Barley | Rothamsted | +P | <0.001 | 0.698 | 1.228 (0.062) | 0.287 (0.071) | −0.285 (0.012) |
| Spring Barley | Rothamsted | -P | 1.297 (0.121) | 0.622 (0.272) | −0.344 (0.041) | ||
| (Sign. effect) | *** | ns | * | ||||
| Spring Barley | Woburn | +P | <0.001 | 0.707 | 1.236 (0.064) | 0.276 (0.076) | −0.273 (0.013) |
| Spring Barley | Woburn | -P | 1.542 (0.156) | 1.271 (0.672) | −0.418 (0.084) | ||
| (Sign. effect) | ** | ns | *** | ||||
| Winter Triticale | Rothamsted | +P | <0.001 | 0.81 | 0.999 (0.022) | 0.021 (0.007) | −0.249 (0.003) |
| Winter Triticale | Rothamsted | -P | 0.95 (0.105) | 0.075 (0.127) | −0.284 (0.074) | ||
| (Sign. effect) | *** | ns | ns | ||||
| Winter Triticale | Woburn | +P/ -P | ns | b | – | – | – |
| Winter Wheat | Rothamsted | +P | <0.001 | 0.819 | 1.093 (0.047) | 0.119 (0.029) | −0.244 (0.005) |
| Winter Wheat | Rothamsted | -P | 1.027 (0.086) | 0.142 (0.065) | −0.248 (0.012) | ||
| (Sign. effect) | ** | ns | ns | ||||
| Winter Wheat | Woburn | +P | <0.001 | 0.594 | 1.059 (0.07) | 0.121 (0.049) | −0.235 (0.011) |
| Woburn | -P | 0.883 (0.064) | 0.042 (0.022) | −0.222 (0.005) | |||
| (Sign. effect) | ns | * | ns | ||||
| Linseed | Rothamsted | +P | <0.001 | 0.845 | 1.21 (0.154) | 0.369 (0.232) | −0.303 (0.036) |
| Rothamsted | -P | 0.973 (0.16) | 0.11 (0.118) | −0.259 (0.0247) | |||
| (Sign. level) | ns | ns | ns | ||||
| Linseed | Woburn | +P | <0.001 | 0.594 | 0.978 (0.091) | 0.090 (0.081) | −0.286 (0.032) |
| Linseed | Woburn | -P | 0.940 (0.141) | 0.098 (0.112) | −0.280 (0.032) | ||
| (Sign. level) | ns | ns | ns | ||||
| Winter Oilseed rape | Rothamsted | +P | <0.001 | 0.415 | 0.747 (0.054) | 0.009 (0.008) | −0.233 (0.002) |
| Rothamsted | -P | 1.19 (0.733) | 0.89 (3.05) | −0.411 (0.52) | |||
| (Sign. effect) | ns | ns | * | ||||
| Winter Oilseed rape | Woburn | +P | <0.001 | 0.763 | 0.93 (0.053) | 0.046 (0.023) | −0.242 (0.007) |
| Woburn | -P | 1.08 (0.165) | 0.275 (0.228) | −0.298 (0.044) | |||
| (Sign. effect) | ns | ns | * |
*The parameter coefficients are significantly different between the added P levels at P < 0.05.
**The parameter coefficients are significantly different between the added P levels at P < 0.01.
***The parameter coefficients are significantly different between the added P levels at P < 0.001.
After 1980 + P is equivalent to P1, P2 and P3 treatments; see Table 3 for further details on the P treatments.
Residual variance exceeds variance of response variate.