简介:FixedammoniumcontentsandNH4^+fixationcapacitiesofsomerepresentativecultivatedsoliscollectedfrom16provincesofChinawerestudied.Resultsshowedthatthecontentsoffixedammoniuminsoilsrangedfrom35to573mgNkg^-1,withanaverageof198mgNkg^-1.Thecontentoffixedammoniumcorrelatedverysignificantlywithmicacontentfortropicalandsubtropicalsoils,whereasthiswasnotthecaseforsoilsinthetemperatezone.AttheendofK-exhaustingexperimentthefixedammoniumcontentincreasedinmostsoilsstudied.However,itdecreasedinsmomtemperatesoils.Generally,fixationofaddedNH4^+couldnotbefoundeitherbeforeorafterK-exhaustingexperimentforhighlyweatheredsoils,includingtropicalsoilsandsoilsderivedfromgranite-gneissorQuaternaryredclaysinthesubtropiczone,whileformostsoilsintheYangtzeRiverdaltatheNH4^+fixationcapacitywasratherhighandincreasedsignificantlyintheK-exhaustedsoils.
简介:为研究注干施药防治松墨天牛幼虫的效果,以4种药剂林间注干施药,测定了施药后防治效果。结果表明:4种注干药剂林间防治后,对松墨天牛幼虫治效果存在极显著差异(P〈0.01),其中以2%甲维盐5、10、15、20倍液,14%吡虫啉5、10倍液,0.3%苦参碱5倍液和5%噻虫啉5倍液防治松墨天牛幼虫效果较佳,均达80%以上。试验结果还表明,4种药剂注干防治对马尾松都有一定的保护作用,其中2%甲维盐对松树的保护效果最好。
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