| The construction of biogas digests in rural areas in China can not only solve the problem of energy use of farmers,but also the biogas slurry produced by fermentation can be used as fertilizer.Based on various soil problems caused by existing unreasonable water and fertilizer management models.In this study,tomatoes,the main cultivated crop in greenhouse in Northwest China,were selected as materials.Combined with the hole irrigation mode,the water and biogas slurry are integrated into the hole on both sides of the root zone of the tomato plant ? Physiological and ecological indexes(plant height,stem diameter,dry matter content,etc.),yield and quality(organic acid,soluble sugar,soluble solids,vitamin C,protein,etc.),water and fertilizer use efficiency and soil environment of greenhouse tomato were studied under different biogas slurry concentration and application frequency.The main findings are as follows:(1)When the concentration of biogas slurry was 20%,the plant height and stem diameter of tomatoes in the two-season experiment could reach the highest level at4-day irrigation frequency.With the increase of application concentration and the increase of irrigation frequency,the plant height and stem diameter showed an upward trend.(2)When the concentration of biogas slurry is 20% and the irrigation frequency is 4 days,the dry matter and yield of tomato in the two seasons can reach the highest,which is significantly higher than that of chemical fertilizer application,and with the increase of the biogas slurry application frequency and the decrease of the concentration,the dry matter and yield of all the biogas slurry treatments is significantly reduced.When the concentration of biogas slurry was reduced to 14%,the yield of fertilizer treatment was the highest,which was higher than that of all biogas slurry treatments.Compared with the 2017,tomato yield decreased by 25.4%in 2018.(3)Under the same conditions,high concentration of biogas slurry is more beneficial to enhance WUE of tomatoes.The hole irrigation mode based on the integrated application of water and biogas slurry can reduce irrigation amount without sacrificing the production of crop material,thus significantly improving the water use efficiency of greenhouse tomatoes.However,compared with the 2017,the WUE value in 2018 decreased by an average of 33.8%.(4)The ratio of sugar to acid in tomato fruits,which had a significant effect onthe flavor quality of tomato fruits,was significantly increased by the application of biogas slurry.With the increase of biogas slurry concentration and irrigation frequency,the ratio of sugar to acid in tomato fruits was significantly increased.Combined with the quality indicators,T1-4 treatment was the best.(5)In the two-year experiment,the soil water content reached the lowest in the mature period.Different biogas concentration and irrigation frequency could affect the soil water content in tomato root zone,and was also affected by greenhouse climate conditions and crop growth characteristics.the soil water content in the root zone decreased significantly due to the different growth climate in 2018.And the content of total nitrogen and total phosphorus in the root zone of all biogas slurry treatments was lower than that of the original soil,while that of fertilizer treatments was the highest,which further increased the content of total nitrogen and total phosphorus in the soil.The application model of the integrated application of water and biogas based on hole irrigation is more convenient for crops to absorb and utilize nutrients.(6)The comprehensive evaluation of yield,water use efficiency and sugar-acid ratio of tomatoes using biogas slurry during the whole growth period based on spatial analysis showed that the irrigation frequency and concentration range of biogas slurry reached the maximum of(?95%)were about 4.0-4.5 days and 18.5-20% in 2017,4.0-4.5 days and 19-20% in 2018. |
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