论文部分内容阅读
长期的产量趋势有助于表现气候与土壤变化,农业措施与技术发展效果的作用。加拿大大草原生产谷物仅约80年。Hill(1954)发现,在Alberta省的Lethbridge
Long-term production trends help to characterize the effects of climate and soil changes, agricultural practices and technological development. The Canadian prairies produce grain for only about 80 years. Hill (1954) discovered Lethbridge in Alberta