磷水平对土壤锌铁铜有效性的影响

红黄壤、黄棕壤、砂姜黑土三类不同性质的土壤,用9个磷(P)水平(0-150ppm,均以P_2O_5计算).分别处理15天及30天.结果发现,几乎在所有P水平处理下的土壤,其有效锌(Zn)前15天表现抑制,含量低于本底值;30天后,都有不同程度的回升,似乎受到促进,但因土质、pH值、本底Zn含量的不同,差异较大. 红黄壤的有效Zn含量与P水平在前15天呈极显著直线负相关,而黄棕壤和砂姜黑土则呈极显著直线正相关;30天后,红黄壤回升到2-3ppm,相关性不显著,而黄棕壤和砂姜黑土则呈显著直线正相关.三种土壤的有效铁(Fe)含量,无论是15天和30天,均与P水平呈极显著的直线负相关,即表现抑制.有效铜(Cu)含量,在红黄壤和砂姜黑土,前15天以任何P水平处理均降到临界值以下,表现抑制;30天后,都有不同程度的回升,略高于临界值,在黄棕壤,前15天呈极显著直线正相关,30天后则相关性不显著,其含量均高于本底值,表现促进,但低于临界值,属严重缺Cu.

P levels and the availability of Zn, Fe and Cu in soil

Three kinds of soil with different properties—red yellow earth.yellow brown earth and shajiang meadow soil were treated with 9 P levels(calculated according to P_2O_5)from 0-150mm in 15 & 30 days respectively. Theresults indicated that the available Zn contents of soil treated with all P leve-ls were inhibitorily and below soil native Zn contents at the first 15 days, andraised in varying degrees with an obvious difference, which varied with thetexture, pH value, & Zn contents of soil after 30 days. Very significant negative correlation of available Zn content with P levels ofred yellow earth was observed at the first 15 days, whereas, both yellow brownearth & shajiang meadow soil showed the opposite, After 30 days, the availableZn content of red yellow earth rose to 2-3 ppm, but no significant correlationwith P levels was there, and both yellow brown earth & shajiang meadow soilstill had a significant positive correlation. the available Fe content of the soilswere very significant negative correlation with P levels during the whole time.The available Cu contents of both red yellow earth & shajiang meadow soil treatedwith any P levels presented below the critical limitation at the first 15 days, andraised just above the critical limitation after 30 days, but yellow brown earthhad a very significant positive correlation between available Cu content & P lev-els at the first 15 days, no significant correlativity was seen after 30 days, allcontents were above soil native value and below the critical limitation. showinga serious deficiency in copper.