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1977年春,我们以Ⅰ-214等6个杨树新品种1年生苗根桩作材料,采用1×1米株行距,在废黄河故道沙土上定植了少量的试验性采穗圃.行间套种草木樨,每年6～7月掩麦并追施一次碳酸氢铵,每亩40斤.为观察发条效果,1978年春,对当年新发条分别齐地面平茬和离地面30厘米平茬.1978年9月进行现场调查,发条效果如下表:
In the spring of 1977, we used 1-year-old seedling root piles of 6 new poplar varieties such as I-214 as materials, and used 1 × 1 meter spacing to planted a small amount of experimental cutting garden on the sand of the old Yellow River. Clogs, each year from June to July overturned wheat and a topdressing of ammonium bicarbonate, 40 acres per acre. In order to observe the clockwork effect, the spring of 1978, respectively, the spring of the new crop parallel ground and 30 cm from the ground stubble .1978 On-site survey in September, the clockwork effect is as follows: