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旱薄碱灾是我省黑龙港流域粮食、棉花生产的障碍因素,其中干旱又是主要限制因素。由于能源及水资源的限制,春旱影响春播保苗,伏旱影响粮棉产量。如1987年伏旱严重,秋粮受灾面积达70—80%,减产2—4成,大面积夏玉米几乎绝收。一、伏旱的形成与危害伏旱是指7—8月份天旱无雨,土壤含水量下降,作物因缺水而短时间萎蔫受害。伏旱出现的机率占40%左右,八十年代以来几乎年年有不同程度的伏旱,以7月中下旬至8月上旬危害最大,常造成秋粮产量低而不稳,棉花蕾铃大量脱落。伏旱常与降雨集中相伴生。季节间降雨分布不均匀是伏旱产生的直接原因。透雨日(≥50mm)出现的时间
Droughts and alkali disasters are the obstacle factors of grain and cotton production in Heilonggang valley in our province, of which drought is the main limiting factor. Due to the limitation of energy and water resources, the spring drought affected the sowing and planting of spring and affected the output of grain and cotton. Such as the severe drought in 1987, autumn grain affected area of 70-80%, cut 2-4 percent, a large area of summer corn almost absolutely. First, the formation of the drought and the hazards of drought refers to the drought in July-August drought, soil moisture decreased, crop short-term wilt due to lack of water damage. The incidence of drought is about 40%. Since the 1980s, there have been varying degrees of drought in almost every year. From late to late July to early August, it is most harmful, which often results in low and unstable autumn grain yield and a large amount of cotton buds fall off. Ambush often accompanied by rainfall concentration. Uneven distribution of rainfall during the seasons is the direct cause of the drought. Thunderstorm days (≥ 50mm) appeared time