4 . the results show that during the 1990 - 1995 , the land use type mainly is infield and garden in qian county experiment area , the land use structure is changing all the time and the rate of annual change is 16 . 49 % , in which the infield and grassland decrease 8 . 40 % and 2 . 55 % while the garden and forest increase 7 . 43 % and 2 . 29 % ; the type of land use type changing is mainly infeile and grassland to garden and forest , in which 68 . 43 hm2 infield chang to garden , 5 . 74 hm2 infield chang to forest , and 19 . 19 hm2 grassland chang to forest 监测结果表明，在1990 ? 1995年间，乾县试区的土地利用类型以耕地和果园为主，土地利用结构不断发生着时空变化，年均变化速度为16 . 79 ，其中耕地与草地分别减少8 . 40与2 . 55 ，而园地与林地分别增加了7 . 43与2 . 29 ；土地利用转换方式以耕地、草地转为园地、林地为主，其中耕地68 . 43公顷转为果园， 5 . 74公顷转为林地， 19 . 19公顷天然草地转为林地。
Under the situation of total irrigation water use decreasing greatly and it is essential to irrigate saline soil ( saline soil and salt soil area constitutes 65 % of the whole infield ) , a saving irrigation experiment study was carried out in hetao irrigation area , and crop response to water and salt stress was studied by way of pot and field experiment 本文在河套灌区总灌水量减少又要解决盐渍化土地（占总耕地面积65 % ）灌溉问题的前提下，针对主要作物油葵，采用苗期盆栽和田间试验相结合的方法进行作物水盐胁迫响应研究。
Although irrigation could enhance output greatly , not all farmers could sink wells because of the economy and infield scales . in the first half of the 20th century , in north china , villages had a lot of custom using and maintaining wells , such as sharing the irrigating wells or borrowing . wells for drinking could use freely , which meant anyone could get water for drink from any well and the own 灌溉虽可大幅度地提高作物产量，但灌溉井的开凿与农户经济状况及农户所经营的耕地规模有关，并不是所有农户都可以开凿灌溉用井，在二十世纪上半叶华北村落中存在着众多的关于水井的使用和维护的习惯做法，如对灌溉井的共用或借用
So we must always adhere to the basic national policy , that is , " quite cherishing , using land resources and protecting infield actually " , and rightly deal with connection in between economic development and resources protection and environment constructing , and ensure sustaining development of social and economy , which is a yardstick of the creation of district ecology environment and economy constructing 因此，必须始终坚持“十分珍惜、合理利用土地和切实保护耕地”的基本国策，正确处理协调好经济发展、资源保护和生态环境建设之间的关系，保障社会经济的可持续发展。这些是区域生态环境与经济建设的准绳。
