過磷酸鈣是我國目前生產最多的一種化學磷肥。它的主要成分為水溶性的磷酸一鈣和難溶於水的硫酸鈣,分別占肥料重量的40%~50%和40%左右;此外,肥料中還含有少量的磷酸、硫酸、非水溶性的磷酸鹽和其他鐵、鋁、鈣鹽等雜質。一般為灰白色或淺灰色粉末,也有顆粒狀的。由於含有遊離酸(磷酸、硫酸),故過磷酸鈣呈酸性,並具有吸濕性,在貯運過程中要注意防潮。實踐證明,過磷酸鈣的利用率較低,一般隻有10%~25%,主zhu要yao原yuan因yin是shi它ta被bei施shi入ru土tu壤rang中zhong後hou,肥fei料liao中zhong的de水shui溶rong性xing磷lin酸suan一yi鈣gai容rong易yi被bei固gu定ding,移yi動dong性xing小xiao。因yin此ci,合he理li施shi用yong過guo磷lin酸suan鈣gai的de原yuan則ze是shi既ji要yao減jian少shao其qi與yu土tu壤rang的de接jie觸chu麵mian積ji,又you要yao盡jin量liang增zeng加jia它ta與yu根gen係xi的de接jie觸chu機ji會hui。為wei此ci,應ying采cai取qu科ke學xue合he理li的de施shi用yong方fang法fa,提ti高gao其qi利li用yong率lv。
集中施和分層施。過磷酸鈣可作基肥、種肥和追肥,但無論作什麼肥,都以集中施用效果好。因為集中施(條施、穴施)kejianshaofeiliaoyuturangdejiechumian,jianshaoguding,tongshizengjialeyugenqundejiechujihui,shifeidiannongdujiaoda,youliyulinsuangenxianggenbiaokuosan,shigenxirongyixishoulinsuyingyang。zaijizhongshidejichushangcaiqufencengshixiaoguogenghao,jidabufenlinfeizuojifeishenshi,shaobufenqianshihuozuozhongfei,huoshuidaodianyanggen。zheyangnengshiyingzuowugenxideshengchangjiqiduifeiliaodexuyao,jimiaoqixufeishaogenxiqian,zhongqigenxichangshenerqiexufeiduo。zuozhongfeihuoyanggenfeishiyaozhuyiguolinsuangaizhongyoulisuanduizhongzihegenxiweihai,yibankeyongxiangdangyulinfeiyongliangde2%~3%的草木灰與其混合堆放半天後再與種子混播,如作秧根肥應把磷肥與1~2倍的腐熟有機肥或細土混合堆漚半天至一天後用水調成糊狀點秧根。
與有機肥混合施。與有機肥混合施可減少磷的固定,因一方麵減少與土壤的接觸,另一方麵有機肥的分解產物可減少土壤中鐵、鋁等對磷的固定。
製成顆粒肥。把過磷酸鈣製成粒徑為3~5haomidekeli,zaigudingliqiangdeturangshangshiyongshibijiaoyouxiaode。yinweitashizhuburongjiechuyouxiaolinde,youxiaoshijianjiaochang,tongshiyoujianshaoyuturangdejiechu。kelifeishiyijixieshiyong,zuozhongfeihenanquan。danlijingbunengtaida,kelitaidahuijianshaolinfeiyugenxidejiechu。zaishihuixingtushangshiyong,buyidingyaozhichengkeli,genjushiyanbiaoming,shiyongfenzhuanghekelizhuangguolinsuangai,suohuochanliangmeiyouduodachayi。
在酸性土上施用,要配施石灰。先施石灰翻犁耙勻後再施磷肥,不要把石灰與過磷酸鈣混合,以免降低磷肥的有效性。
zuogenwaizhuifei。jiangguolinsuangaizuogenwaipenshiyeshiyizhongjingjiyouxiaodefangfa,takeyifangzhilinzaiturangzhongbeiguding,younengbeizuowuzhijiexishou。penshiqianxianjiangguolinsuangaijia10倍水浸泡過夜,取其清液用水稀釋到所需濃度後噴施。噴施濃度各類作物不同,水稻、小麥等穀類作物可用1%~3%浸出液,果樹可用2%左右濃度,棉花、蔬菜等可用1%的濃度。
過磷酸鈣特別適合缺硫的土壤施用,即使在不缺硫的土壤中,對於特別需硫的作物如穀類、豆類、花生、牧草等也是很適用的。
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