隨著玉米產量水平的提高,關鍵生育期要求對土壤有效鉀的供應相應增加。許多玉米長期定位試驗的結果證明,當產量增加10%~20%時shi,吸xi鉀jia量liang也ye出chu現xian了le相xiang應ying增zeng加jia。適shi當dang提ti高gao玉yu米mi植zhi株zhu組zu織zhi的de含han鉀jia量liang才cai能neng保bao持chi穩wen定ding的de高gao產chan。在zai北bei方fang春chun播bo玉yu米mi區qu盡jin管guan土tu壤rang速su效xiao鉀jia含han量liang處chu於yu較jiao高gao水shui平ping(如70~130毫克/公斤),施(shi)用(yong)鉀(jia)肥(fei)仍(reng)有(you)增(zeng)產(chan)效(xiao)果(guo)。特(te)別(bie)是(shi)一(yi)些(xie)速(su)效(xiao)鉀(jia)含(han)量(liang)中(zhong)等(deng),緩(huan)效(xiao)鉀(jia)的(de)容(rong)量(liang)也(ye)不(bu)大(da)的(de)土(tu)壤(rang),就(jiu)要(yao)考(kao)慮(lv)高(gao)產(chan)田(tian)增(zeng)施(shi)鉀(jia)肥(fei)。因(yin)此(ci)在(zai)以(yi)產(chan)量(liang)目(mu)標(biao)作(zuo)為(wei)推(tui)薦(jian)施(shi)鉀(jia)的(de)主(zhu)要(yao)依(yi)據(ju)時(shi),對(dui)有(you)效(xiao)鉀(jia)含(han)量(liang)較(jiao)低(di)的(de)土(tu)壤(rang)增(zeng)施(shi)鉀(jia)肥(fei)是(shi)保(bao)證(zheng)高(gao)產(chan)的(de)必(bi)要(yao)措(cuo)施(shi)。還(hai)要(yao)注(zhu)意(yi)一(yi)些(xie)土(tu)壤(rang)有(you)效(xiao)鉀(jia)水(shui)平(ping)即(ji)使(shi)中(zhong)等(deng)時(shi),增(zeng)施(shi)適(shi)量(liang)鉀(jia)肥(fei)也(ye)有(you)良(liang)好(hao)的(de)效(xiao)果(guo)。
增(zeng)加(jia)種(zhong)植(zhi)密(mi)度(du)對(dui)需(xu)鉀(jia)量(liang)的(de)影(ying)響(xiang)。當(dang)前(qian)雜(za)交(jiao)玉(yu)米(mi)高(gao)產(chan)栽(zai)培(pei)中(zhong)常(chang)常(chang)通(tong)過(guo)增(zeng)加(jia)密(mi)度(du)而(er)使(shi)產(chan)量(liang)得(de)到(dao)大(da)幅(fu)度(du)提(ti)高(gao),與(yu)此(ci)同(tong)時(shi)高(gao)密(mi)度(du)植(zhi)株(zhu)對(dui)農(nong)田(tian)的(de)吸(xi)鉀(jia)量(liang)也(ye)明(ming)顯(xian)提(ti)高(gao)。所(suo)以(yi)在(zai)密(mi)度(du)增(zeng)加(jia)時(shi),如(ru)不(bu)相(xiang)應(ying)增(zeng)施(shi)鉀(jia)肥(fei)或(huo)提(ti)高(gao)土(tu)壤(rang)鉀(jia)的(de)有(you)效(xiao)性(xing),則(ze)作(zuo)物(wu)因(yin)吸(xi)鉀(jia)難(nan)以(yi)保(bao)證(zheng),產(chan)量(liang)可(ke)能(neng)下(xia)降(jiang)或(huo)達(da)不(bu)到(dao)理(li)想(xiang)水(shui)平(ping)。但(dan)是(shi)增(zeng)施(shi)鉀(jia)肥(fei)5~6公斤/muhou,chanliangbujiangfaneryousuotigao。youqizaiyouxiaojiahanliangbugaobingyouguangaitiaojiandeyumidikuai。suoyizaiduiyumituijianshifeishi,weileshiyingjiaogaodemiduhechanliangshuiping,shijialiangyaobichangguiliangshidangtigao。
密植高產玉米栽培中協調鉀肥和氮肥的平衡供應很關鍵。通常情況下,為了實現高產目標而偏多施氮,由此加重了植株對病蟲害如莖腐、根腐、青枯病等的感染率。如果不相應增加鉀肥供應,會形成氮鉀失調的症狀。缺鉀首先減弱了玉米莖、yedekangzheqiangduhebiaopihoudu,jijiazhongledaofudekenengxing,youtigaoleyumiduichonghaihebinghaideminganxing。zhongsuozhouzhi,zaiyingyangyuansuzhongdanhejiaduiyumikangbingxingdeyingxiangdouda,danerzhedezuoyongfangxiangbutong,danpianduowangwanghuizengjiayumiduibinghaideminganxing,erjiadezuoyongzexiangfankeyizengjiazuowudekangbingxing。
田tian間jian缺que鉀jia診zhen斷duan與yu追zhui肥fei補bu救jiu措cuo施shi。當dang春chun玉yu米mi進jin入ru拔ba節jie階jie段duan,從cong小xiao喇la叭ba口kou到dao大da喇la叭ba口kou的de生sheng育yu時shi期qi是shi它ta快kuai速su生sheng長chang時shi期qi,對dui氮dan磷lin鉀jia要yao素su的de需xu求qiu都dou有you所suo增zeng長chang,通tong常chang在zai實shi際ji生sheng產chan中zhong習xi慣guan於yu隻zhi追zhui施shi氮dan肥fei而er不bu注zhu意yi追zhui施shi鉀jia肥fei。但dan是shi在zai春chun玉yu米mi高gao產chan密mi植zhi栽zai培pei中zhong,到dao底di需xu不bu需xu要yao追zhui肥fei,隻zhi要yao看kan一yi看kan田tian間jian生sheng長chang的de玉yu米mi,觀guan察cha植zhi株zhu生sheng長chang狀zhuang況kuang,就jiu可ke以yi得de到dao回hui答da。那na就jiu是shi經jing常chang在zai上shang午wu九jiu十shi點dian鍾zhong的de時shi候hou跑pao到dao玉yu米mi地di看kan,尤you其qi刮gua風feng的de天tian氣qi更geng要yao看kan,如ru果guo看kan到dao春chun玉yu米mi的de葉ye片pian在zai上shang午wu就jiu打da蔫nian了le,那na它ta就jiu是shi告gao訴su你ni 我缺鉀了 。因yin為wei對dui於yu一yi般ban不bu急ji需xu灌guan溉gai的de農nong田tian,正zheng常chang健jian壯zhuang的de玉yu米mi植zhi株zhu,上shang午wu不bu會hui出chu現xian葉ye片pian打da蔫nian現xian象xiang的de,到dao中zhong午wu後hou出chu現xian打da蔫nian現xian象xiang才cai是shi正zheng常chang的de。因yin為wei鉀jia可ke以yi影ying響xiang葉ye片pian氣qi孔kong的de關guan閉bi和he增zeng加jia植zhi株zhu保bao水shui功gong能neng。缺que鉀jia時shi氣qi孔kong阻zu力li大da,不bu能neng正zheng常chang關guan閉bi,導dao致zhi玉yu米mi體ti內nei水shui分fen損sun失shi嚴yan重zhong而er出chu現xian打da蔫nian現xian象xiang。這zhe時shi必bi須xu追zhui施shi鉀jia肥fei加jia以yi補bu救jiu,最zui可ke行xing的de措cuo施shi就jiu是shi追zhui施shi氯lv化hua鉀jia5~8公斤,溝施或穴施後,覆土即可。
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