| The area of facility agriculture has been increasing, and facility production plays a more and more important role in modern agriculture. Nowadays, greenhouses prove to be an effective approach to adjust the industrial structure and increase farmers'income, which is of great promotion effect on the development of local agriculture and economy. However, a series of soil problems such as nutrient enrichment and salt accumulation in greenhouse will appear after many years of planting, and these problems will threaten agricultural sustainable development. Therefore, it is necessary to research the soil quality in greenhouses to provide scientific and reasonable management measures. And it will guide the development of facilities agriculture, and provide theoretical basis for scientific fertilization management and sustainable use of soil as well.In the study, soil in greenhouses with different age was taken as samples, and soil in open field was taken as CK at the same time. What's more, the impact of planting years on soil physical, chemical and biological properties were studied. Then, the fuzzy comprehensive evaluation of soil was conducted by fuzzy comprehensive evaluation method. The results are as follows:1. Along with the growth of the years of planting, soil bulk density and moisture capacity slightly increased first and decreased, and they achieved maximum respectively at5a and10a. Soil pH showed a small drop at3a, and then maintained stable level. Conductivity and nitrate content increased first and then decreased, which achieved maximum respectively at5a and3a. Nitrate content was together at top soil, but was within the limits of safty. A certain extent soil salinization emerged there.2.Organic matter content was high compared with CK, but it was below the demand of high quality standard of vegetable fields. Besides, total and available content of N, P and K were all high. Along with the growth of the years of planting, the content of total P, total K and availble P was straight upwards, while the content of organic matter, total K, available N and available K increased first and then decreased, and they achieved their maximum at10a.3.The activity of urease and invertase were downward trend on the whole, while the activity of protease and catalase remained relatively stable level. 4.Urease activity had significant negative correlation with organic matter (R2=0.890*, P<0.05), total nitrogen (R2=-0.911*, P<0.05), available phosphorus (R2=-0.920*, P<0.05) and available potassium (R2=-0.927*, P<0.05), and the correlation between invertase activity and total phosphorus was significantly negative (R2=-0.900*, P<0.05). What's more, the activity of protease and catalase had no significant correlation with all nutrient indices.5.The weight of each index was obtained by principal component analysis, and divided each index into3standards referring to related research results. Then, soil fuzzy comprehensive evaluation was carried out. Level Ⅰ means better soil quality, and level Ⅲ means worse soil quality.According to the result, the soil with10and15years of planting belonged to the level Ⅰ soil, the soil with1,3and5years of belonged to the level Ⅱ soil, and the soil in the open belonged to the level Ⅲ soil. That is to say that greenhouse with older age has a better soil quality.To maintain sustainable productivity of soil in greenhouses, the application of high quality to fertilizer should be strengthened to improve the content of organic matter, meanwhile, we should also pay attention to reduce the application of chemical fertilizer and control the ratio of NPK fertilizers. |
PDF Full Text Request