Phosphorus

About: Phosphorus is a research topic. Over the lifetime, 53120 publications have been published within this topic receiving 939731 citations. The topic is also known as: element 15 & P.

The effect of phosphorus on the formation of hyphae in soil by thevesicular‐arbuscular mycorrhizal fungus, glomus fasciculatum

Abstract: Summary Hyphae formed in soil by the vesicular-arbuscular (VA) mycorrhizal fungus, Glomusfasciculatum (Thaxter sensu Gerd.) Gerd. and Trappe were extracted using the membrane filter techniqe and their length was estimated by the grid intersection method. The effect of phosphorus on the formation of this external mycelium was assessed after sampling procedures had been investigated. Phosphorus supply was varied from amounts severely deficient to those adequate for the growth of subterranean clover. After 6 weeks, the alleviation of severe phosphorus deficiency increased both the length of infected root and the length of external hyphae per centimetre of infected root. Further additions of phosphorus decreased both of these measurements. However, the level of added phosphorus at which the most external hyphae was formed per centimetre of infected root was higher than the level of phosphorus which gave the greatest length of infected root. The increase in phosphorus supply which gave the greatest increase in the length of external hyphae per centimetre of infected root also decreased the formation of vesicles within infected roots. At phosphate levels adequate for growth of mycorrhizal plants, there was little development of either external hyphae in soil or vesicles within the mycorrhizal roots.

Phosphorus, Nitrogen, and Algae in Lake Washington after Diversion of Sewage

Abstract: After diversion of sewage effluent from Lake Washington, winter concentrations of phosphate and nitrate decreased at different rates. From 1963 to 1969, phosphate decreased to 28 percent of the 1963 concentration, but nitrate remained at more than 80 percent of the 1963 value. Free carbon dioxide and alkalinity remained relatively high. The amount of phytoplanktonic chlorophyll in the summer was very closely related to the mean winter concentration of phosphate, but not to that of nitrate or carbon dioxide.

Iron-bound phosphorus in marine sediments as measured by bicarbonate-dithionite extraction

Abstract: A sequential five-step extraction scheme for phosphorus pools in freshwater sediment was modified for use in marine sediments. In the second step phosphate bound to reducible forms of iron and manganese (‘iron-bound P’) is extracted by a bicarbonate buffered dithionite solution (BD-reagent). The extraction scheme was tested on sediment from 16 m water depth in Aarhus Bay, DK and used in two other marine sediments: Kattegat at 56 m and Skagerrak at 695 m depth. By comparing the BD-extractable P-pool with both the pool of iron in the BD-fraction and the pool of oxidized, amorphous or poorly crystalline iron (am.FeOOH), highly significant correlations (p < 0.001) were observed in all three sediments. Thus, we conclude that the BD-reagent was very specific for iron-bound P. Further evidence for this came from two experiments: 1) Enhanced BD treatment did not result in additional phosphate extraction and 2) by sequential extraction of phosphorus pools in pure cultures of diatoms and cyanobacteria no phosphate was recovered in the BD-fraction. The pool of am.FeOOH was very important for controlling porewater phosphate concentration which was inferred from the significant inverse relationships between the two parameters (p < 0.001) in all sediments studied. Further, an isotopic exchange experiment with 32POf4/p3− revealed that BD-extractable P was by far the most exchangeable P-pool even deep in the sediment where the pool size was small. Iron-bound P made up 33–45% of total P in the surface sediments. The ratio between iron-bound phosphate and am.FeOOH was 8–11 in Aarhus Bay and Kattegat. In Skagerrak the ratio was 17, which may indicate that the iron mineral extracted from this sediment is less capable of adsorbing phosphate or less saturated with phosphate.