The effect of different nitrogen and phosphorus sources on pH and the availability of mineral nutrients in the root/soil interface of Larix gmelinii seedlings were studied by means of root-mat method. The results show...The effect of different nitrogen and phosphorus sources on pH and the availability of mineral nutrients in the root/soil interface of Larix gmelinii seedlings were studied by means of root-mat method. The results showed that the addition of NH+4-N decreased the pH in the root/soil interface, while the addition of NO-3-N increased the pH in contrast with the control treatment. The sort of the P sources and the distance from the root plane remarkably influenced the changes of pH in the root/soil interface induced by the addition of the nitrogen sources. Compared with the addition of only NH+4-N, the extent to which the pH in the root/soil interface decreased was obviously smaller when treated by NH+4-N and rock P. When treated with different P sources, the contents of available P in the root/soil interface were affected by the sort of the N sources. When treated with soluble P, the contents of the available P in the root/soil interface obviously increased for the addition of both NH+4-N and NO-3-N. When treated with rock P, the contents of the available P increased only in the area 0～3 mm from the root plane for NH+4-N, whereas the contents of available P in the root/soil interface changed little for NO-3-N. The results above showed that the protons excreted by the roots were the main driving force for the solution of the rock P in the root/soil interface. The availability of Fe in the root/soil interface increased as a result of acidity induced by the NH+4-N, whereas the availability of Fe in the root/soil interface decreased because of the pH increase induced by the NO3-N. The effect of different N sources on the availability of Fe in the root/soil interface was also affected by the sort of P sources. The concentrations of P、Fe in the leaves remarkably differed when treated by different N、P sources and concentrations of the P、Fe in the root/soil interface were correlated to those in the leaves of the seedlings.展开更多
文摘The effect of different nitrogen and phosphorus sources on pH and the availability of mineral nutrients in the root/soil interface of Larix gmelinii seedlings were studied by means of root-mat method. The results showed that the addition of NH+4-N decreased the pH in the root/soil interface, while the addition of NO-3-N increased the pH in contrast with the control treatment. The sort of the P sources and the distance from the root plane remarkably influenced the changes of pH in the root/soil interface induced by the addition of the nitrogen sources. Compared with the addition of only NH+4-N, the extent to which the pH in the root/soil interface decreased was obviously smaller when treated by NH+4-N and rock P. When treated with different P sources, the contents of available P in the root/soil interface were affected by the sort of the N sources. When treated with soluble P, the contents of the available P in the root/soil interface obviously increased for the addition of both NH+4-N and NO-3-N. When treated with rock P, the contents of the available P increased only in the area 0～3 mm from the root plane for NH+4-N, whereas the contents of available P in the root/soil interface changed little for NO-3-N. The results above showed that the protons excreted by the roots were the main driving force for the solution of the rock P in the root/soil interface. The availability of Fe in the root/soil interface increased as a result of acidity induced by the NH+4-N, whereas the availability of Fe in the root/soil interface decreased because of the pH increase induced by the NO3-N. The effect of different N sources on the availability of Fe in the root/soil interface was also affected by the sort of P sources. The concentrations of P、Fe in the leaves remarkably differed when treated by different N、P sources and concentrations of the P、Fe in the root/soil interface were correlated to those in the leaves of the seedlings.
