一、看天就是根據天氣的冷暖,即日平均氣溫。掌握在立冬後日平均氣溫7℃~8℃時開始,到“小雪”後平均氣溫3℃~5℃結束。群眾的經驗是:不(bu)凍(dong)不(bu)消(xiao),冬(dong)灌(guan)過(guo)早(zao),隻(zhi)凍(dong)不(bu)消(xiao),冬(dong)灌(guan)晚(wan)了(le),夜(ye)凍(dong)晝(zhou)消(xiao),冬(dong)灌(guan)正(zheng)好(hao)。嚴(yan)防(fang)澆(jiao)水(shui)過(guo)遲(chi),地(di)麵(mian)結(jie)冰(bing),造(zao)成(cheng)窒(zhi)息(xi)和(he)機(ji)械(xie)損(sun)傷(shang)死(si)苗(miao),澆(jiao)水(shui)過(guo)早(zao),易(yi)遭(zao)受(shou)旱(han)凍(dong)危(wei)害(hai)。
二、看地就是根據墒情、土質、地質確定澆水順序。一般越冬前的土壤含水量相當於田間最大持水量的80%以上時可不澆凍水。低窪地要提早澆水,防止春季返漿嚴重,影響麥苗生長;崗沙地失墒快,需臨近封凍時澆水,防止冬季幹凍死苗;黏土地和坷垃較多的地要掌握在夜凍晝消時灌水,一凍一融有利於粉碎坷垃,疏鬆土壤。
三、看苗一般要掌握早麥先澆,晚麥後澆;壯苗先澆,弱苗後澆;無分蘖的麥田不澆。這樣可以防止因地溫降低,影響冬前發育。但嚴重缺墒的例外。
四、kanshuigenjushuiyuantiaojianheshuiliangdaxiaoquedingjiaoshuishunxu。zaishuiyuanchongzudetiaojianxia,yinggenjushangshuyuanze,lizhengjiaoduanshijianneijiaowan。shuiyuanbuzushi,jiaoshuishijianyingshidangtiqian,baozhengzaiturangjiedongqianjiaowan,danxianjiaodeshuiliangyidaxie。yibanshuolai,dongshuidouyaojiaotou,lianjiedishang。shangqingchadeyaoduojiao,shangqinghaoyixiedeshaojiao。jiaodongshuihou,yaoshidangchuhua,songtubaoshangheshishiyamai。
凡含水量符合下列條件的麥田,可不冬灌:沙土地在18%以上;沙壤土在20%以上;黏土地在22%以上,地下水位又高的麥田。此外,凡底墒充足的晚茬麥田也可不冬灌。這類麥田因冬前生育期短,有效積溫不足,故葉片少、根少、meiyoufennie,suoyiyaomianjiaodongshui,yichongfenliyongchudonghezaochunlianggedongrongshiqideyouxiaojiwenlaitigaofenniejiefujindediwen,zhengquduofennie,duochangyixiecishenggen。danduizheleibudongguandemaitianbixuzaishangdongqianchuhua,songtubaoshang,tigaodiwen,yilixiaomaianquanyuedong。
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