Jinjin Zhang^1,2 , Zengqiang Duan¹ , Xun Li^1,2

1. The State key Laboratory of the Soil and Agricultural Sustainable Development, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, 210008, P.R. China
2. Graduate School of Chinese Academy of Sciences, Beijing, 100049, P.R. China
Author    Correspondence author
Molecular Soil Biology, 2011, Vol. 2, No. 1   doi: 10.5376/msb.2011.02.0001
Received: 24 Feb., 2011    Accepted: 16 May, 2011    Published: 29 Jun., 2011

This is an open access article published under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Zhang et al., 2011, The Classification Criteria for NO₃^- type Soil Secondary Salinization in Cucumber Cultivated Greenhouse, Molecular Soil Biology, doi:10.5376/msb.2011.02.0001

 The use of nitrogen fertilizers in intensive agricultural systems in China has dramatically increased for protected vegetale farming in recent years. The excessive use of nitrogen fertilizer has obviously resulted in salinizing soil,  namely soil secondary salinization (short for SSS), which has become a significant environmental stress for crops, such as cucumber cultivated in greenhouse, in the protected farming in China. Therefore it is urgent and necessary to propose some guidelines for farmers to manage of the SSS problem in the areas of facility agriculture. In this study, the criteria of SSS classification based on the concentration of NO₃^- was studied in cucumber cultivating greenhouses (Cucumis sativus L. cv. Dongfangmingzhu) in Taizhou, Jiangsu province, neighboring shanghai of East China. After the soils in the tested greenhouses were treated with different concentrations of nitrate, the SSS levels expressed by electrical conductivity (EC) were detected at 0.89 ds/m for control, 2.78 ds/m for treatment 1 (T1), 3.65 ds/m for treatment 2 (T2), 4.66 ds/m for treatment 3 (T3) and 6.15 ds/m for treatment 4 (T4). The results showed that there were significant relationships between NO₃^- contents and soil EC in the surface soil, which indicated that the changes of soil characters resulting from the changes of nitrate concentrations in soil in the greenhouse should be used as criteria for classifying the ranks of the NO₃^- type SSS. The ranks of the NO₃^-  type SSS was significantly related with the plant height and yield of cucumber (p < 0.05). In this research, we proposed the criteria of classification for NO₃^- type SSS in cucumber cultivated greenhouse in Delta of Yangtze River with five ranks based on the effects of SSS on the plant height and yield of cucumber, that is: levelâ… : 0.89 ds/m < EC < 2.03 ds/m, level â…¡: 2.03 ds/m < EC < 3.76 ds/m level â…¢: 3.76 ds/m < EC < 5.32 ds/m, level â…£: 5.32 ds/m< EC < 6.15 ds/m, and level â…¤: EC > 6.15 ds/m. This study might provide a practical guideline for evaluating NO₃^- type SSS in facility agriculture, and also might be importance of the protected vegetable farming, particular in cucumber cultivated in greenhouse and plastic covering house, to monitor and adjust salinity in soil for Cucumis sativus.

Soil secondary salinization (SSS); NO₃^- type SSS; Classification criteria; Protected farming; Facility agriculture; Cucumber (Cucumis sativus L.)