Abstract:

It's of great significance to find out the status of nitrate nitrogen in the soil of protected vegetable fields for the nitrogen management of regional protected vegetable fields and the sustainable development of protected vegetable industries. Based on sampling and testing, the study adopted a large sample survey method to comprehensively analyze and evaluate the status of nitrate nitrogen in the soil of protected vegetable fields in Xi’an. The results showed that: (1) the average content of nitrate nitrogen in the soil of the protected vegetable fields was 55.22 mg/kg, and the abundance and deficiency level was medium. (2) The regional variation of soil nitrate nitrogen content in the protected vegetable fields was obvious, among which the average value of soil nitrate nitrogen content in Lantian County was the highest (92.40 mg/kg), and the average value of soil nitrate nitrogen content in Zhouzhi County was the lowest (28.10 mg/kg). (3) WIth the increase of planting years, the content of nitrate nitrogen in the soil of protected vegetable fields generally presented a downward trend, and the average value of nitrate nitrogen in the soil of protected vegetable fields in 1-5 years (57.67 mg/kg) was the highest. (4) The content of nitrate nitrogen in the soil of protected vegetable fields showed obvious regularity with the change of soil texture. The coarser the soil texture, the lower content of nitrate nitrogen, and the finer the soil texture, the higher the content of nitrate nitrogen. (5) There was a very significant positive correlation between nitrate nitrogen and available phosphorus, but no significant correlation with organic matter, alkali-hydrolyzable nitrogen, available potassium, pH, soil electronic conductivity, etc. In general, there was no excessive accumulation of nitrate nitrogen in the surface soil of the protected vegetable fields in Xi’an, but attention should be paid to nitrogen reduction and balanced fertilization in the process of fertilization management.

Key words: protected vegetable fields, nitrate nitrogen, planting years, soil texture, nutrients