Effect Of Alkaline Liquid Compound Fertilizeron Alleviation Of Cadmium And Lead Accumulation In Rice And Its Property Of Slow Release In Soil

Heavy metal pollution on farmland is a serious issue in China.Cadmium?Cd?and lead?Pb?contamination in rice paddies has beenthe most common one.Because high availability of the Cd and Pb in soil caused by soil acitification.Asa result rice absorbed an abnormal high quantity of Cd and Pb in rice and human being health have been threatened through the food chain.The absorption and accumulation of Cd and Pb in rice were positively correlated with the available Cd and Pb content in soil.Soil acidification was the main reason of high available cadmium and lead in rice paddies.Since last 40 years in China,due to excessive and irrational application of chemical fertilizer,especially nitrogen fertilizer,soil acidifying significantly and thecadmium and lead become mobile in soil.Therefore,how to raise the soil p H value and then reduce cadmium and lead activity during normal fertilization are urgent tasks.In order to deal with the problem,a new type of fertilizer named alkaline liquid compound fertilizer?ALF?was developed by Guangdong Provincial R&D Center of Environmental Friendly Fertilizer Science and Technology with the purpose to supply nutrients during rice cultivation and increase soil pH valuesimultaneously.Thus the available cadmium and lead content in soil would be decreased while the rice growth.Rice pot experiment and leaching experiment were conducted in the present paper and two kinds of ALF were tested tostudy the effectiveness of slow release properties of the fertiizers in the soil and the influences of them on availability of cadmium and lead in and their accumulaton in rice.The purposes of the studies were to determin fertilizer effience of the ALF in differentsoil types during rice production and the feasibility of the ALF to reduce cadmium and lead pollution in rice.The results of the studies could provide theoretical basis for reclaiming soil acidity and controlling Cd and lead Pb contamination in paddiesby use of ALF.The main results are as followings.1.Comparedwith ordinary fertilizers,soil pH value could be significantly increased by the application of ALF during rice growth.The soil p H value increased by 0.44 and 0.14units respectively three days after the first time of application of ALF1 and ALF2,while0.13 and 0.17 unitsrespectivelyat harvest time.2.Compared with ordinary fertilizers,the available Cd and Pb contents were significantly reduced in paddy soil by use of ALF1 and ALF2 from middle to final growth phase.The available Cd content in soil decreased by 15.3%and 28.9%respectively by application of ALF1 and ALF2.The available Pb content in soil decreased by 15.9%and 10%respectively by application ofALF1 and ALF2 at the harvest time.3.The Cd and Pb contents in each organof rice at harvest were in order of root>stem>grain>leaf.Compared with ordinary fertilizers,the Cd and Pb contents in rice grains and other organs significantly decreased by the application of ALF1 and ALF2.The grains Cd content of ALF1 and ALF2 treatments were 0.051 mg·kg^-1 and 0.021 mg·kg^-1 which were decreased by 40.0%and 75.3%respectively.Compared withordinary fertilizers,the grainPb content of ALF1 and ALF2 treatments were 0.583 mg·kg^-1 and 0.565 mg·kg^-1,being decreased by 30%and 32.1%.4.Compared with ordinary fertilizers,ALF1 and ALF2 didn't affect the rice plant height,panicle number,grain weight and seed setting rate.However,ALF2 increased rice grain number by 14.7 in average.ALF1 and ALF2 increased effective panicles by 4.6 and3.4 respectively.5.Compared with ordinary fertilizers,ALF1and ALF2 possessed slowrelease ability in acidic soils?red soil in Guangdong and sandy soil in Hainan?,expressed with leaching resistance,reducing nitrogen leaching rate,depressing nitrogen nitrification rate and increasing nitrogen residue significantly.However,in calcareous soil?sandy soil in Henan?,the slow release effectivenessof ALF1 and ALF2 was poor.During the first 30 days leaching,compared with ordinary fertilizers,the amount of nitrogen leached in ALF1treatment decreased by26.7%and 27.7%respectively in thesandy soil in Henanand red soil inGuangdong.The amount of nitrogen leached in ALF2one decreased by 26.0%and 25.9%respectivelyin the two soils.There was no significant difference of the leaching between two kinds of ALF and ordinary fertilizers in Henan sandy soil.At the end of the leaching,the residual nitrogen inALF1 and ALF2 were 6.51 to 8.78 times more than that of ordinary fertilizers.