磷肥诱导下层植被伴生的辐射松苗生长、磷素营养和土壤有效磷变化

通过在温室条件下施加不同剂量的重过磷酸钙(0,50和100mg·kg-1P),对典型水铝英石土壤(Orthic Allophanic Soil)的土壤植物有效磷、磷素营养和伴生有金雀花(Cytisus scoparius)或黑麦草(Lolium multiflorum)的辐射松苗木生长变化情况进行了研究。结果表明,施加磷肥增强了辐射松根际和磷素匮乏土体的有效磷。与辐射松苗伴生的金雀花、黑麦草根际土壤有效磷也增加。辐射松新枝和老枝松针、茎和根系中磷含量随施加重过磷酸钙剂量的增加而增加;但是金雀花、黑麦草对辐射松苗磷素营养的影响依赖于土壤磷状态。未施肥处理下,与金雀花伴生的辐射松新枝和老村松针、茎和根系中磷含量要高于与黑麦草伴生的辐射松苗,而施肥处理下,结果相反。这可能与金雀花生长大量消耗土壤中有效磷有关。因为,在两个施肥剂量(50mg·kg-1P和100mg·kg-1P)上,与金雀花伴生的辐射松根际土壤中Bray-2磷含量始终低于与黑麦草伴生的辐射松根际土壤。此外,在施肥浓度100mg·kg-1下,与金雀花伴生的辐射松苗干特质量低于黑麦草伴生的辐射松。说明在中、高施肥水平,辐射松苗与黑麦草伴生生长好于与金雀花伴...

Phosphorus fertilizer induced changes in the soil available P,the P nutrition and the growth of Pinus radiata seedlings grown in association with understory

A study was carried out to investigate changes in the soil plant-available P, the P nutrition and the growth of Pinus radiata seedlings grown in association with understory, broom (Cytisus scoparius L.) or ryegrass (Lolium multiflorum) on Orthic Allophanic Soil, following the application of three rates of triple superphosphate (TSP) (0, 50, and 100 mg·kg-1P) under a glasshouse condition. The application of P fertilizer enhanced P availability in the rhizospheric of radiata seedlings and the bulk soils in a P-deficient site. P availability in the rhizospheric soils of ryegrass and broom, grown in association with radiata, were also increased by the presence of radiata roots. P concentrations in new shoot needles, old shoot needles, stem and roots of radiata pine increased with increase rates of TSP application, but the effects of ryegrass and broom on P nutrition of radiata seedlings depended on the soil P status. In the absence of P fertilizer addition (control treatment), P concentrations in new shoot needles, old shoot needles, stem, and roots of radiata grown in association with broom were higher than those with ryegrass, whereas, when P fertilizer was added (50 and 100 mg·kg-1) the P concentration was lower. This is probably related to the growth of broom that may have removed much of the plant-available P in the soil as indicated by the consistently lower Bray-2 P concentration in the rhizosphere soil of radiata in association with broom than that in the rhizosphere soil of radiata in association with grass at the two high P rates. Furthermore, in the high P fertile soil (application rate of 100 mg·kg-1), the dry matter yield of radiata was lower when it was grown with broom than with ryegrass. This result suggests that in moderate to high P fertile soils, P. radiata seedlings grow better with ryegrass than with broom, because broom grows vigorously in high P fertile soil and competes with P. radiata for P and perhaps for other nutrients as well.