Alleviation of organic manure on aluminum toxicity in acid red soil

Aluminum is the most abundant metal that makes up 7% of the earth's crust and occurs in a number of different forms in the soil.If the soil pH 5 or even 5.5,as is now the case accounted for 40% of the arable lands in the world, the harmless oxides and aluminosilicates could be solubilized into toxic forms, generally referred to Al3+,which is a primary factor limiting plant growth.A possible alternative to ameliorate Al toxicity is the application of organic manure such as rice straw.A pot experiment was conducted to investigate the alleviation of straw on aluminum toxicity in acid red soil.The result revealed that adding 0.5%,1% and 1.5% organic straw carbon significantly increased soil pH value and active exchangeable aluminum;while decreased adsorbent hydroxy aluminum. Soil pH negatively correlated with soil exchangeable aluminum and adsorbent hydroxyl aluminum.with the correlation equations being y=2193.9x + 11545,R2 = 0.9798** and y=-655.34x + 9748,R2 = 0.7837** respectively.Soil exchangeable aluminum and adsorbent hydroxyl aluminum were significantly negative correlated to root length and P and K content in the ground parts.It is the main limiting factor controlling nutrients uptake.