氮肥品種很多，根據化合物形態可分為銨態氮肥、硝態氮肥和酰胺態氮肥。銨態氮肥包括碳酸氫銨、硫酸銨、氯化銨(an)、氨水、液氨等(deng)；硝態氮肥(fei)包(bao)(bao)括硝酸銨(an)、硝酸鈉、硝酸鈣(gai)等(deng)；酰胺態氮肥(fei)包(bao)(bao)括尿素、氰氨化鈣(gai)（石灰氮）等(deng)。為了提高(gao)氮肥(fei)的施用(yong)效(xiao)果，科(ke)學(xue)選擇氮肥(fei)品種十(shi)分重要。

一般來(lai)說，馬鈴薯(shu)等碳水化(hua)合(he)物(wu)含量(liang)高的(de)作(zuo)物(wu)，適宜(yi)(yi)施(shi)(shi)用(yong)(yong)(yong)銨(an)(an)態氮(dan)(dan)肥(fei)。小(xiao)麥(mai)、玉米(mi)等禾(he)谷類作(zuo)物(wu)施(shi)(shi)用(yong)(yong)(yong)銨(an)(an)態氮(dan)(dan)、硝(xiao)(xiao)態氮(dan)(dan)同樣有效(xiao)，但在多雨地區，為防(fang)止氮(dan)(dan)素淋失，仍以(yi)施(shi)(shi)用(yong)(yong)(yong)銨(an)(an)態氮(dan)(dan)肥(fei)為宜(yi)(yi)。稻(dao)田(tian)(tian)宜(yi)(yi)選用(yong)(yong)(yong)尿素、氯(lv)化(hua)銨(an)(an)效(xiao)果(guo)較好，而不宜(yi)(yi)選用(yong)(yong)(yong)硫(liu)酸銨(an)(an)及(ji)硝(xiao)(xiao)態氮(dan)(dan)肥(fei)。因(yin)(yin)為硫(liu)酸根(gen)在水田(tian)(tian)中(zhong)易還原為硫(liu)化(hua)氫，使(shi)稻(dao)根(gen)發黑甚至腐爛(lan)，硝(xiao)(xiao)酸根(gen)在水田(tian)(tian)中(zhong)易隨水淋失及(ji)發生反(fan)硝(xiao)(xiao)化(hua)作(zuo)用(yong)(yong)(yong)造(zao)成(cheng)(cheng)氮(dan)(dan)的(de)損(sun)失。麻類作(zuo)物(wu)則宜(yi)(yi)選用(yong)(yong)(yong)氯(lv)化(hua)銨(an)(an)，因(yin)(yin)氯(lv)離子可增(zeng)(zeng)加纖維的(de)韌(ren)性和拉力。煙(yan)草以(yi)硝(xiao)(xiao)態氮(dan)(dan)和銨(an)(an)態氮(dan)(dan)配合(he)施(shi)(shi)用(yong)(yong)(yong)效(xiao)果(guo)好，硝(xiao)(xiao)態氮(dan)(dan)可提(ti)高煙(yan)草的(de)燃燒性，而銨(an)(an)態氮(dan)(dan)能促(cu)進(jin)煙(yan)葉內芳香族揮發油的(de)形(xing)成(cheng)(cheng)，增(zeng)(zeng)加煙(yan)草的(de)香味，因(yin)(yin)此，兩種形(xing)態的(de)氮(dan)(dan)肥(fei)配合(he)施(shi)(shi)用(yong)(yong)(yong)可提(ti)高其品質。