杨树生长迅速,喜大水大肥,培育杨树速生丰产林,必须进行灌溉与施肥。但多年生产实践证明,灌溉和追肥都必须科学进行,否则不仅达不到预期效果,甚至会影响树木生长,造成干梢或死亡。杨树灌溉要求次数少而水量足。一般每年可进行3次,第一次要在早春进行,叫做“返青水”。杨树经过冬季自身大量失水,春季开始生长活动时,及时灌水对抽梢放叶非常有益。但必须抓准时机,适时进行。近几年有的地方,在早春2月下旬或3月上旬就给杨树灌“返青水”,当时土壤尚未化冻,灌水反而降低地温,推迟根系活动时间,导致地上部与地下部失去水分平衡,造成干梢或死亡。“返青水”必须在早春土壤已化冻,地温达到3℃左右。辽西地区一般在3月末4月初才能进行。第二次要灌 Poplar grow rapidly, hi large water big fat, cultivating poplar fast-growing high yield forest, must be irrigation and fertilization. However, many years of production practice have proved that irrigating and top dressing must all be carried out scientifically, otherwise it will not only fail to achieve the desired results, but may even affect the growth of trees and cause stems or deaths. Poplar less irrigation requirements and sufficient water. Generally can be carried out 3 times a year, the first time in early spring, called “green water.” Poplar after a lot of water loss in winter itself, the spring began to grow activities, timely irrigation is very beneficial to the shading leaves. However, we must seize the opportune moment and proceed promptly. In recent years, in some areas in recent years, early spring or early March gave poplar irrigation “green water”, when the soil has not yet been frozen, irrigation instead lower ground temperature, postponed the root activities of time, resulting in aboveground and underground lost water balance , Resulting in dry tip or death. “Green water” must be in the early spring soil has been thawing, ground temperature reached about 3 ℃. Western Liaoning Province generally in late March early April to proceed. The second irrigation