Study On The Suitable Model Of Water/Biogas Slurry Integrated Irrigation Instead Of Chemical Fertilizer In The Whole Growth Period Of Tomato

In order to explore the suitable model of replacing chemical fertilizer with biogas slurry,pot experiment and field experiment were carried out in greenhouse.In the pot experiment,the biogas slurry irrigation concentration is 20%,and 3 irrigation modes were set up:conventional irrigation（CI,simultaneous and equal watering on both sides of the pot）,alternate partial root-zone irrigation（APRI,alternate watering on both sides of the pot）and fixed partial root-zone irrigation（FPRI,fixed watering on one side of the pot）.We also adopted two biogas slurry irrigation methods including biogas slurry hole irrigation and surface irrigation.There were 6 treatments in pot experiment,including XF（Hole irrigation with APRI）、XJ（Hole irrigation with CI）、XG（Hole irrigation with FPRI）、BF（Hole irrigation with APRI）、BJ（Surface irrigation with CI）、BG（Surface irrigation with FPRI）.The amount of irrigation for CI is 1.0Ep APRI and FPRI is 60%of the CI.The field experiment used biogas slurry hole irrigation method,the concentration of biogas slurry was 20%,and set three irrigation levels such as 0.5Ep,0.7Ep and 0.9Ep.Three fertilization schemes were designed,including soil mixed with biochar and irrigated by biogas slurry,biogas slurry only and chemical fertilizer only.There were 9 treatments in field experiment,including SZ_0.5（Biochar and biogas slurry are applied together,and the irrigation amount is0.5Ep）、SZ_0.7（Biochar and biogas slurry are applied together,and the irrigation amount is 0.7Ep）、SZ_0.9（Biochar and biogas slurry are applied together,and the irrigation amount is 0.9Ep）、H_0.5（Apply chemical fertilizer only and the irrigation amount is 0.5Ep）、H_0.7（Apply chemical fertilizer only and the irrigation amount is 0.7E_P）、H_0.9（Apply chemical fertilizer only and the irrigation amount is 0.9E_P）、Z_0.5（Apply biogas slurry only and the irrigation amount is0.5Ep）、Z_0.7（Apply biogas slurry only and the irrigation amount is 0.7Ep）、Z_0.9（Apply biogas slurry only and the irrigation amount is 0.9E_P）。This paper discusses the effects of different biogas slurry application schemes on tomato physiological and ecological indicators,yield,water use efficiency and tomato fruit quality indicators,and discusses the impact of different biogas slurry application schemes on tomato comprehensive quality and comprehensive benefits.The following main conclusions are obtained:（1）The two-season pot experiment showed that the distribution of root amount and water content in the upper layer（0-15cm）was larger than that in the lower layer（15-30cm）,but distribution of soil moisture and root system in the root zone of biogas slurry hole irrigation is more uniform than that of surface irrigation.（2）Combined with the two-season pot experiment,it can be seen that CI is beneficial to plant height but not to stem stalk thickening,but APRI promotes the growth of tomato stem thickening.Under the condition of biogas slurry hole irrigation,tomato plant height and stem thickness are larger than biogas slurry surface irrigation treatments.The two-season pot experiment showed that the total dry matter and yield of tomato under CI were respectively higher than APRI and FPRI treatments.The experiment also showed that the root/rhoot ratio of tomato under APRI were respectively higher than FPRI and CI treatments.Under the condition of biogas slurry hole irrigation,total dry matter and yield are larger than biogas slurry surface irrigation treatments.（3）The comprehensive quality and comprehensive benefits of tomato in the two-season pot experiment were XF treatment as the best and BG as the worst.Under the biogas slurry surface application method or hole application method,the comprehensive quality and comprehensive benefit of tomato are APRI as the largest,and the FPRI the smallest;under the same irrigation mode,the biogas slurry hole application of tomato comprehensive quality and comprehensive benefit are greater than the biogas slurry surface application treatments.（4）Field experiments showed that the change in tomato stem thickness was the same as the plant height.Under the same fertilization scheme,tomato plant height and stem thickness increased first and then decreased with the increase of irrigation.Under the same irrigation level,the plant height and stem thickness of tomato in the chemical fertilizer treatment group were the largest,and the biogas slurry and biochar co-application treatment was the smallest.And when soil was mixed with biochar,the total dry matter and yield of tomato increased with the increase of biogas slurry application,while in the case of soil without mixed biochar,the total tomato dry matter and yield increased first and then decreased with the increase of biogas slurry application.The total dry matter and yield of tomato treated with chemical fertilizer also increased with the increase of irrigation.（5）Field experiments show that the comprehensive quality and comprehensive benefits of tomato are the highest with Z_0.7 treatment and the smallest with SZ_0.5 treatment.Under different fertilization schemes,the comprehensive quality and comprehensive benefits of tomato increased first and then decreased with the increase of irrigation volume.The application of biogas slurry only in the case of medium and low level irrigation is more conducive to achieving the best quality and ensuring yield of tomato fruits.Compared with chemical fertilizers,the application of biogas slurry can also ensure the comprehensive quality and comprehensive benefits of tomatoes at high water levels,but the combined application of biogas slurry and biochar is more conducive to achieving the best quality and higher Yield.