針對(dui)蔬(shu)菜(cai)(cai)(cai)地(di)不(bu)同類型施肥(fei),是(shi)蔬(shu)菜(cai)(cai)(cai)實現優(you)質高(gao)產(chan)的重要措施。筆者在(zai)鄉下(xia)常聽(ting)到(dao)一(yi)些(xie)菜(cai)(cai)(cai)農反映,一(yi)些(xie)生菜(cai)(cai)(cai)地(di)(即剛種植蔬(shu)菜(cai)(cai)(cai)的土地(di))多(duo)施肥(fei)增(zeng)產(chan)效(xiao)果明(ming)顯,而常年種植蔬(shu)菜(cai)(cai)(cai)的熟菜(cai)(cai)(cai)地(di),容(rong)易造成肥(fei)害,多(duo)施肥(fei)有時(shi)反而會減產(chan)。

蔬(shu)菜(cai)在對肥(fei)(fei)料的(de)吸(xi)收(shou)(shou)(shou)和利用上,它(ta)們的(de)能(neng)力(li)強弱(ruo)取決于自身纖(xian)維內蔗(zhe)糖(tang)(tang)濃度(du)高低之(zhi)間產生(sheng)的(de)“滲(shen)坑(keng)”,依靠壓力(li)差促(cu)進營(ying)養(yang)(yang)液(ye)流動(dong),以(yi)葉(xie)片的(de)水(shui)分(fen)(fen)蒸騰拉動(dong)根(gen)、莖對肥(fei)(fei)料的(de)運(yun)轉與吸(xi)收(shou)(shou)(shou),使其在平衡(heng)與不平衡(heng)中(zhong)交換運(yun)行,而(er)(er)使菜(cai)株(zhu)生(sheng)長(chang)發育。剛種(zhong)蔬(shu)菜(cai)的(de)生(sheng)菜(cai)地(di),土壤營(ying)養(yang)(yang)液(ye)濃度(du)小,“滲(shen)坑(keng)”大,植株(zhu)體(ti)中(zhong)對以(yi)蔗(zhe)糖(tang)(tang)為主要成(cheng)分(fen)(fen)傳(chuan)(chuan)遞(di)形(xing)式的(de)信號強,調控(kong)能(neng)力(li)大,對這(zhe)類菜(cai)地(di)增施(shi)(shi)肥(fei)(fei)料,正迎合了蔬(shu)菜(cai)對肥(fei)(fei)料的(de)迫切需(xu)求和迅速吸(xi)收(shou)(shou)(shou)利用,促(cu)成(cheng)了多(duo)(duo)施(shi)(shi)肥(fei)(fei)、多(duo)(duo)增產的(de)明顯效果。而(er)(er)熟菜(cai)地(di)因(yin)本身的(de)土壤營(ying)養(yang)(yang)消耗(hao)大,“滲(shen)坑(keng)”小,植株(zhu)中(zhong)蔗(zhe)糖(tang)(tang)信號傳(chuan)(chuan)遞(di)和調控(kong)能(neng)力(li)弱(ruo),甚至在一些經(jing)常(chang)種(zhong)菜(cai)的(de)熟菜(cai)地(di),因(yin)營(ying)養(yang)(yang)成(cheng)分(fen)(fen)充足,而(er)(er)失去了“滲(shen)坑(keng)”作用,對這(zhe)類菜(cai)地(di)施(shi)(shi)肥(fei)(fei)過多(duo)(duo),不僅不能(neng)促(cu)進蔬(shu)菜(cai)對肥(fei)(fei)料的(de)吸(xi)收(shou)(shou)(shou)利用,相反(fan)會導致菜(cai)株(zhu)體(ti)內的(de)營(ying)養(yang)(yang)成(cheng)分(fen)(fen)受阻,發生(sheng)許(xu)多(duo)(duo)有害于蔬(shu)菜(cai)正常(chang)生(sheng)長(chang)的(de)生(sheng)理障礙(ai),造(zao)成(cheng)爛(lan)(lan)種(zhong)死(si)(si)苗毀種(zhong),或脫水(shui)死(si)(si)苗或爛(lan)(lan)根(gen)死(si)(si)苗等許(xu)多(duo)(duo)被“撐死(si)(si)”的(de)現象(xiang)。

許多常年種(zhong)植(zhi)蔬(shu)菜(cai)(cai)的(de)熟菜(cai)(cai)地,會(hui)出現(xian)一(yi)些(xie)土壤(rang)(rang)(rang)老化(hua)現(xian)象。主要表現(xian)是(shi)病菌(jun)和(he)殘留毒害增加,土壤(rang)(rang)(rang)板結(jie),有機質(zhi)匱乏,因(yin)(yin)大(da)量(liang)施用(yong)復合(he)肥、二銨等化(hua)肥,忽視有機肥施用(yong),造成(cheng)土壤(rang)(rang)(rang)板結(jie),透氣性(xing)降低,好(hao)氣性(xing)微(wei)(wei)生(sheng)物活(huo)性(xing)下降,根系發育不(bu)(bu)(bu)良,易受病害。過量(liang)施用(yong)化(hua)肥,菜(cai)(cai)地pH值升(sheng)高,土壤(rang)(rang)(rang)鹽(yan)漬化(hua)加重(zhong)(zhong)。微(wei)(wei)量(liang)元素(su)不(bu)(bu)(bu)足,多年連(lian)作土壤(rang)(rang)(rang)中的(de)鋅、硼(peng)、鐵、鉬等微(wei)(wei)量(liang)元素(su)被(bei)蔬(shu)菜(cai)(cai)大(da)量(liang)吸收,又得(de)不(bu)(bu)(bu)到補(bu)充時(shi),會(hui)使這(zhe)些(xie)微(wei)(wei)量(liang)元素(su)逐年減(jian)少,嚴(yan)重(zhong)(zhong)影(ying)響蔬(shu)菜(cai)(cai)生(sheng)長(chang)發育。土壤(rang)(rang)(rang)耕層(ceng)較淺(qian),菜(cai)(cai)地多用(yong)人工(gong)翻掘,實行茬茬相連(lian)的(de)間作套種(zhong)園(yuan)地翻掘更(geng)少,土層(ceng)日漸變(bian)淺(qian),影(ying)響根系伸展,而生(sheng)菜(cai)(cai)地因(yin)(yin)種(zhong)植(zhi)蔬(shu)菜(cai)(cai)時(shi)間不(bu)(bu)(bu)長(chang),一(yi)般不(bu)(bu)(bu)會(hui)出現(xian)上(shang)述(shu)現(xian)象,因(yin)(yin)而施肥利用(yong)率高,增產(chan)的(de)效果顯著。

對(dui)于這(zhe)兩種(zhong)類型的(de)(de)(de)蔬(shu)(shu)菜(cai)(cai)地(di)(di),要讓(rang)蔬(shu)(shu)菜(cai)(cai)生長(chang)正常,獲得增產增收的(de)(de)(de)好效(xiao)(xiao)益,必須合(he)理(li)施(shi)肥(fei)(fei)(fei)(fei)(fei),讓(rang)菜(cai)(cai)地(di)(di)保持(chi)適(shi)宜的(de)(de)(de)營養濃度,讓(rang)蔬(shu)(shu)菜(cai)(cai)保持(chi)適(shi)中(zhong)的(de)(de)(de)植物(wu)“滲坑”效(xiao)(xiao)應。科學施(shi)肥(fei)(fei)(fei)(fei)(fei)的(de)(de)(de)原(yuan)(yuan)(yuan)則(ze)是(shi)(shi)(shi):一(yi)是(shi)(shi)(shi)增施(shi)大量腐(fu)熟(shu)的(de)(de)(de)有(you)機肥(fei)(fei)(fei)(fei)(fei)料(liao)。特別(bie)是(shi)(shi)(shi)對(dui)熟(shu)菜(cai)(cai)地(di)(di)宜停(ting)止使用(yong)(yong)化(hua)肥(fei)(fei)(fei)(fei)(fei)和(he)(he)單一(yi)的(de)(de)(de)氮(dan)肥(fei)(fei)(fei)(fei)(fei)。二是(shi)(shi)(shi)堅持(chi)常年(nian)施(shi)用(yong)(yong)植物(wu)秸(jie)稈、廄肥(fei)(fei)(fei)(fei)(fei)和(he)(he)人畜糞等有(you)機肥(fei)(fei)(fei)(fei)(fei)料(liao),以改善(shan)土(tu)(tu)(tu)(tu)(tu)壤(rang)的(de)(de)(de)團粒(li)結(jie)構,使水肥(fei)(fei)(fei)(fei)(fei)氣熱明(ming)顯協(xie)調。對(dui)已酸(suan)(suan)化(hua)或(huo)(huo)堿化(hua)的(de)(de)(de)土(tu)(tu)(tu)(tu)(tu)壤(rang)進行改造,除增施(shi)有(you)機肥(fei)(fei)(fei)(fei)(fei)外,還應適(shi)量施(shi)用(yong)(yong)中(zhong)性(xing)(xing)肥(fei)(fei)(fei)(fei)(fei)料(liao),如(ru)土(tu)(tu)(tu)(tu)(tu)壤(rang)呈(cheng)酸(suan)(suan)性(xing)(xing)可施(shi)石灰或(huo)(huo)草木灰中(zhong)和(he)(he),土(tu)(tu)(tu)(tu)(tu)壤(rang)呈(cheng)堿性(xing)(xing),可施(shi)硫酸(suan)(suan)銨或(huo)(huo)過(guo)磷酸(suan)(suan)鈣調節,以改善(shan)菜(cai)(cai)土(tu)(tu)(tu)(tu)(tu)的(de)(de)(de)酸(suan)(suan)化(hua)性(xing)(xing)質(zhi)。三(san)是(shi)(shi)(shi)實行不同科蔬(shu)(shu)菜(cai)(cai)的(de)(de)(de)合(he)理(li)輪作(zuo)倒茬,無論是(shi)(shi)(shi)生菜(cai)(cai)地(di)(di)還是(shi)(shi)(shi)熟(shu)菜(cai)(cai)地(di)(di),不宜在同一(yi)塊菜(cai)(cai)地(di)(di)上連(lian)續幾茬都種(zhong)同一(yi)種(zhong)蔬(shu)(shu)菜(cai)(cai)。應經常輪作(zuo)倒茬。四是(shi)(shi)(shi)堅持(chi)科學的(de)(de)(de)施(shi)肥(fei)(fei)(fei)(fei)(fei)原(yuan)(yuan)(yuan)則(ze)。按每畝(mu)保持(chi)純(chun)氮(dan)19公(gong)(gong)斤,有(you)效(xiao)(xiao)磷7公(gong)(gong)斤,純(chun)鉀30公(gong)(gong)斤。施(shi)肥(fei)(fei)(fei)(fei)(fei)前,先(xian)測(ce)試(shi)土(tu)(tu)(tu)(tu)(tu)壤(rang)中(zhong)有(you)效(xiao)(xiao)含(han)量,然(ran)后測(ce)算需(xu)要補(bu)充的(de)(de)(de)品種(zhong)和(he)(he)數(shu)量,再視(shi)品種(zhong)、苗情(qing)決定施(shi)用(yong)(yong)方法和(he)(he)數(shu)量。一(yi)般原(yuan)(yuan)(yuan)則(ze)是(shi)(shi)(shi):“生菜(cai)(cai)地(di)(di)”和(he)(he)瘠薄土(tu)(tu)(tu)(tu)(tu)壤(rang)的(de)(de)(de)菜(cai)(cai)地(di)(di)多施(shi)點(dian);“熟(shu)菜(cai)(cai)地(di)(di)”和(he)(he)肥(fei)(fei)(fei)(fei)(fei)沃(wo)土(tu)(tu)(tu)(tu)(tu)壤(rang)的(de)(de)(de)菜(cai)(cai)地(di)(di)少施(shi)點(dian)。氮(dan)、磷、鉀比例為(wei)2.5:0.9:5.5。適(shi)當補(bu)充硼(peng)、鋅肥(fei)(fei)(fei)(fei)(fei),注重穴施(shi)多元(yuan)素蔬(shu)(shu)菜(cai)(cai)專用(yong)(yong)肥(fei)(fei)(fei)(fei)(fei)。對(dui)肥(fei)(fei)(fei)(fei)(fei)害苗及(ji)時(shi)控肥(fei)(fei)(fei)(fei)(fei),根外噴施(shi)生長(chang)調節劑。發(fa)生鹽害、肥(fei)(fei)(fei)(fei)(fei)害時(shi),及(ji)時(shi)給菜(cai)(cai)地(di)(di)澆水,覆蓋瘠薄土(tu)(tu)(tu)(tu)(tu),壓(ya)鹽并緩沖土(tu)(tu)(tu)(tu)(tu)壤(rang)營養濃度,防止蔬(shu)(shu)菜(cai)(cai)被(bei)肥(fei)(fei)(fei)(fei)(fei)“撐死”。