砒砂岩物质组成及其对养分含量的影响

Effect of Composition on Nutrient of Pisha Sandstone

对不同颜色（紫色、白色、粉色和灰色）的35个砒砂岩样品的矿物成分、化学成分及养分含量进行了分析,并在此基础上对砒砂岩物化特性对其肥力的影响进行了探讨。结果表明：1砒砂岩矿物成分主要为石英、长石、蒙脱石、方解石,含量分别为13%～55%、23%～56%、5%～28%、1%～25%,石英含量相对较低,说明岩石发育不够成熟,长石易风化,蒙脱石遇水膨胀,方解石易分解,导致砒砂岩抗蚀能力较弱,养分易流失;2砒砂岩化学成分中不稳定组分Na_2O、K_2O、CaO性质活泼但含量低,三组分含量总和为3.4%～15.0%,组分流失严重,砒砂岩持水保肥能力低;3受砒砂岩矿物组成、化学成分及当地降雨条件影响,砒砂岩总体养分含量非常低,按全国统一划分的六级制土壤养分含量分级表,砒砂岩pH值、有机质、全氮、全磷、全钾和速效磷含量为六级,速效氮含量为五级,速效钾含量为四级。

The mineral composition, chemical composition and nutrient content of 35 Pisha sandstone samples with different colors （ purple, white, pink and grey） were analyzed and the influence of the characteristics of sandstones to the fertility was discussed. The conclusions are as follows： a） the main mineral components in sandstone are quartz, feldspar, montmorillonite and calcite, each content is 13%-55%, 23%-56%, 5%-28% and 1%-25% respectively. The content of quartz is relatively lower indicating the rock is not mature, feldspar is easily weathered, montmorillonite is swelling in water and calcite is easy to decompose, resulting in weak corrosion resistance and easy loss of nutrients; b） Unstable chemical compositions （Na20, K20 and CaO） of sandstone are active but low content. The sum of these three components in Pisha sandstone is 3.4%-15.0%, indicating the serious loss of water and fertilizer and; c） Influenced by mineral composition, chemical composition and local rainfall conditions, the overall nutrient content of Pisha sandstone is very low. According to the national unified six-level soil nutrient content classification, the pH value, organic matter, total nitrogen, total phosphorus, total potassium and available phosphorus are in the sixth level, available nitrogen is in the fifth level and available potassium is in the fourth level.