The factors affecting soil fertility are: river harnessing, fertilizer application, and the changes in cropping system and land utilization after the adoption of high yield hybrid verities.
影响肥力变化的因子包括河流治理、施肥、高产品种使用后种植制度和土地利用程度的变化等等。
The first part involves historical changes of water resources management system of the Shiyang River Basin.
第一部分为石羊河流域水资源管理体系的历史演变。
The key factors involved in the changes in the Sihe river system are the invasion of the Yellow river and the opening of the Grand Canal.
泗河水系河道变迁的主要因素是黄河夺泗和南北大运河的开发。
Since the Neogene, the ancient Songhua-Liao River system have undergone several changes with the alternation of fluvial and lacustrine formation on a large scale.
现代松辽水系是在松辽盆地地质构造、古地貌发育的基础上，几经变迁逐渐演变而成的。晚第三纪以来，古松辽水系经历了几次大规模的河湖交替。
The water system of the upper reaches of the Jialing River experienced tremendous changes over the historical period.
嘉陵江上游诸水在历史时期发生过重大的水系变迁。
The water system of the upper reaches of the Jialing River experienced tremendous changes over the historical period.
嘉陵江上游诸水在历史时期发生过重大的水系变迁。
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