Improving Greenhouse Soil And Cucumber Growth Under Irrigation With Saline Water By Application Of Straw Biological-Reactor And Compost

The shortage of high-quality water resources has become a major limiting factor for the development of protected vegetable production and fanners’ income in Ningxia, leading to the use of saline water for crop irrigation to alleviate the shortage of high-quality water resources. However, irrigation with low-quality water often results in negative effects on plant growth due to salt stress. Thus, the sustainable use of saline water should be conducted based on the mitigation of crop salt stress and the enhancement of crop yields. To alleviate crop salt stress induced by irrigation with saline water, this article investigated the effects of high-carbon compost (HCC) applicated at 0-20cm soil layer and staw biolofical-reactor (SBR) applicated at 20-40cm soil onprotected cucumber soil environment and crop growth under irrigation with saline water. The main results are as follows:(1) Compared to fresh water irrigation (FWI), saline water irrigation (SWI) significantly decreased root-zone (0-40cm) soil water content, increased Na accumulation and pH, and finally limited the availablility of soil nutrients. However, under SWI, HCC and SBR increased soil organic matter and then enhanced soil water hold capacity, improved soil porocity and increased Na leaching. In addition, these two soil amendments efficiently decreased soil pH and increased inorganic N, available P and K in soils.(2) Compared to FWI, SWI significantly decreased the population of soil cultuable microorganisms, and bacteria in particular, in root-zone, and decreased bacterial divercity and amino acids and amines utilization by microbes. However, under SWI, HCC and SBR efficiently reduced the degradation of soil microbial environment mentioned above.(3) Compared to FWI, SWI significantly decreased K+/Na+ratio in plants and NPK absorption by plants. However, under SWI, HCC and SBR increased K+/Na+ ratio in plants and enhanced NPK absorption by plants. In addition, the increase of K+/Na+ ratio in plants was higher under SBR treatment than under HCC treatment. The HCC enhanced N and K absorption by plants, while SBR enhanced P absorption by plants.(4) Compared to FWI, SWI significantly decreased intercellular CO2 concentration, transpiration rate and net photosynthetic rate in leaves in autumn-winter season, and reduced plant biomass and fruit yield in all cultivation seasons. However, HCC and SBR efficiently reduced the negative effects of SWI on crop growth. Additionally, SWI decreased solubale solids and sugers in fruit in the first two cultivation seasons, but reversed this trend in the last two cultivation seasons.(5) On the aspect of soil environment and crop growth improvement, for most properties the combination of HCC and SBR did not show additive effect. Moreover, in the last cultivation season, SWI limited crop growth under HCC and SBR treatments.The results mentioned above suggests that the application of HCC and SBR could alleviate crop salt stress caused by SWI and maintain yields during short-term cultivation (4 cultivation seasons or 2 cultivation years). However, for the actual production, the rotation of SWI and FW, combined with HCC and SBR for reducing FWI frequency, was recommended during the 4th cultivation season.