Study On Effects Of Water-fertilizer Coupling And Limited Amount Index Of Nitrate On Vegetables In Cold And Land Semiarid Region

With vegetables industrialization enlargement of scale and the nitrate of vegetable pollution. On the basis of the investigation in the fields, the paper adopts the little district testing to probe into the impact on nitrate content in celery and celery output after reaping in term of water fertilizer coupling .and to study celery nitrate dynamic change regular within breeding time and nitrate content remains in 0-40cm of soil after reaping with different N , P level and pour different water,The field investigation results indicated that celery nitrate content is significantly different between old vegetable area and new vegetable area in Bashang,beside celey content of nitrate in old vegetable area are higher than new vegetable area, and there is a lot of exceeding standard phenomena, such as the underwater has trend to be polluted. The different edible parts and kinds of celery impact the content of nitrate.The little districting test is proved that to the dynamic change regular within breeding time of nitrate of celery, three factors pass or exceed low are unfavorable to normal growth of plant only when three factors keep a suitable amount, namely while dealing with N270P90W4500 , can celery grow better. Three factors have obvious influence on the content of celery and celery output after celery reap, its nfluence order is the former W> P> N. the latter W> N> P; Threshold value exists to react , When controlling any two factors as the middle amount level, threshold value fluctuates in range The former is N 375kg/hm2, 38.8 kg/hm2