尿素屬酰胺態氮肥,目前是氮肥的主要品種,在所使用的氮肥品種中,尿素占到一半以上。其主要特點是:
(1)在固體氮肥中含氮量最高。一般含氮(N) 46%。
(2)shuirongxingdesuxiaodanfei。niaosuzaishiruturangqian,tadehuaxuexingzhiwending,buxiangtansuanqingannayangzaikongqizhongyifenjie,shiguangdanongminxiaidedanfeipinzhong。niaosuzuozhuifei,yongliangshao,jianxiaokuai。
(3)尿素是中性、fenzitaiyoujidanhuawu,zuowugenxinenggouzhijiexishoudefenzitainiaosu,danshulianghenshao。niaosushiruturanghou,zhiyouzaiturangzhongniaomeidezuoyongxia,beishuijiezhuanhuachengantaidanyihou,cainengdaliangdibeizuowugenxixishou。
(4)niaosuxujingzhuanhuacainengbeizuowudaliangxishou。niaosuzaiturangzhongzhuanhuadechanwushitansuananhetansuanqingan,yinci,niaosushiruturanghoudenongyehuaxuexingzhuangyutansuanqinganxiangsi,tatongyangyehuifashengandehuifasunshi,suoyiyaoshenshifutu。nazhongrenweiniaosubushi“氣兒肥”可以表施是一種誤解。
二、施用技術
尿niao素su可ke以yi作zuo基ji肥fei和he追zhui肥fei施shi用yong,一yi般ban不bu直zhi接jie做zuo種zhong肥fei。因yin為wei掌zhang握wo不bu好hao,高gao濃nong度du的de尿niao素su會hui影ying響xiang種zhong子zi發fa芽ya和he幼you根gen生sheng長chang。如ru果guo必bi須xu做zuo種zhong肥fei施shi用yong,要yao與yu種zhong子zi分fen開kai,而er且qie尿niao素su的de用yong量liang也ye不bu宜yi多duo。
1、基肥
niaosuzuojifeishiyongshi,qishiyongliangyaojingdaxisuan,yinweiniaosudehandanlianggao,shigaonongdudanfei,shiyongliangyidingyaoshidang,fouzehuizaochengyingyangshitiao,jiangdidansuliyonglv。yongniaosuzuojifeiyidingyaoshirutucengdeyidingshendu,youqishizaiweijianxingdeshihuixingturangshang,ruguobiaoshiniaosu,andehuifasunshiliangbitansuanqinganhaiyaoyanzhong,keda30%~60%。
2、追肥
糧食作物在分孽期或拔節期施用,可采用溝施或穴施,施肥後覆 土蓋嚴,防止水解後氨的揮發。尿素在土施作追肥時,施肥時期要比硫酸銨、碳tan酸suan氫qing銨an等deng其qi他ta速su效xiao氮dan肥fei品pin種zhong提ti前qian幾ji天tian施shi用yong,因yin為wei尿niao素su隻zhi有you轉zhuan化hua成cheng銨an態tai氮dan後hou才cai可ke大da量liang被bei作zuo物wu吸xi收shou。到dao底di提ti前qian多duo少shao天tian,要yao看kan季ji節jie和he溫wen度du,早zao春chun天tian氣qi(低溫10℃)要提前6~7天,春末夏初(16~20℃)提前3~4天,夏季提前1~2天即可。在砂土地上漏水漏肥較嚴重,每次肥量不宜過多。
科學施用尿素應注意以下事項:
(1)尿素作追肥用時,既可以土施於作物根尖部,也適宜於作葉麵噴施。
(2)尿素適用於各種作物的葉麵噴施,合適的濃度一般為0.2%~2.0%之間,因作物種類和生育期而有所不同。尿素葉麵噴施時,一定要注意副成分縮二脲的含量要低於0.5%。
(3)尿(niao)素(su)不(bu)適(shi)合(he)作(zuo)種(zhong)肥(fei),主(zhu)要(yao)是(shi)因(yin)為(wei)含(han)氮(dan)量(liang)高(gao),與(yu)種(zhong)子(zi)同(tong)時(shi)使(shi)用(yong)容(rong)易(yi)造(zao)成(cheng)出(chu)苗(miao)不(bu)齊(qi)和(he)燒(shao)苗(miao)。有(you)的(de)尿(niao)素(su)質(zhi)量(liang)不(bu)好(hao),含(han)有(you)一(yi)定(ding)量(liang)的(de)縮(suo)二(er)脲(niao)對(dui)種(zhong)予(yu)發(fa)芽(ya)和(he)幼(you)苗(miao)有(you)毒(du)害(hai)作(zuo)用(yong)。
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