Variation Laws of Soil Nutrients in Solar Greenhouses with Different Cultivation Ages

The effects of cultivation age on soil nitrate and fertility in greenhouse were investigated through field survey and sampling analysis.The results showed that the content of soil nitrate in greenhouse in Shouguang was relatively high,and gradually increased with the increase of cultivation age(1～6 years);it also gradually decreased with the deep of the 0~60-cm soil layer and was seriously accumulated in the top soil.The contents of soil available N,P and K in greenhouse affected greatly by the fertilizer rate,also gradually increased with the increase of cultivation age,so there was a significant increase in 40~60-cm soil layer,which brought about a potential threaten to the ecological environment.The content of soil organic matter in greenhouse rapidly increased with the increase of cultivation age and had not much change after the cultivation for 5 years.In this test,the content of soil organic matter in greenhouse did not reach the level of the first-class vegetable soil.