Effects Of Biogas Slurry Ratio And Irrigation Amount On Tomato Growth And Soil Environment In Root Zone

With the development of the rural biogas project and the growing area of planting vegetables in China,the exploration of a sustainable development way with resources that can be recycled has gradually become the focus of attention.This project selects tomato cultivated in facility agriculture as the selection material,and combines hole irrigation technology,according to a multiple-low-dose irrigation principles,water and biogas slurry are regularly and quantitatively irrigation into the hole near the root of the plant to study the physiological and ecological indicators(plant height,stem diameter,dry matter content,chlorophyll content,etc.),yield quality(soluble solids,vitamin C,protein,etc.),the efficiency of water and fertilizer utilization and the impact of the soil environment for the whole growth period of tomato in different ratios of biogas slurry and different Irrigation amount.The main findings are as follows:(1)With the increase of biogas slurry ratio and irrigation amount,with the continuous development of the growing period,the plant heights and stem diameters of tomato in winter and spring showed an increasing trend,and there was no significant difference at the seedling stage,but then the difference gradually increases;In a certain amount of irrigation amount(0.8Ep),with the increase of biogas slurry ratio,plant height also increased,but the stem diameter increased first and then decreased;in a certain biogas slurry ratio(1:4),with the increase of irrigation amount,the plant height also increased,but the stem diameter is increased first and then decreased.And the dynamic process of growth changes were similar.(2)In winter and spring,the main root length of tomato showed a trend of T3>T4>T2>T1>T5 in the whole growth period,that is,the length of the main root decreased with the increase of biogas slurry ratio or the increase of irrigation amount,while the leaf area showed an opposite trend,that is T5>T1>T2>T4>T3;When the irrigation amount(0.8Ep)is certain,with the increase of biogas slurry ratio,root weight,stem weight,leaf weight,fruit weight and total biomass increased gradually;when the slurry ratio(1:4)is certain,stem weight,leaf weight increased with irrigation amount increased,while the fruit weight and the total biomass in the late growth stage increase first and then decrease with the increase of irrigation amount.(3)The chlorophyll content of tomato leaves in winter and spring is similar.When the irrigation amount(0.8Ep)is certain,the content of chlorophyll a,b and(a+b)in leaves increases with the increase of the ratio of biogas slurry.That is,T1>T2>T3,while(a/b)shows the opposite trend;When the ratio of biogas slurry(1:4)is certain,the contents of chlorophyll a,b and(a+b)in the leaves increase with the increase of the ratio of biogas slurry,that is,T5>T1>T4,while(a/b)shows the opposite trend.(4)The ratio of different biogas slurry and irrigation amount had significant effects on the yield,quality and economic benefit of tomato in winter and spring.The yield per plant showed the same trend as the output value per hectare,that is,T1>T5>T2>T4>CF>T3>CK.The yield per hectare and the output value per hectare of the spring tomato were better than those of the winter.In winter and spring,the output value per hectare of T1 treatment was the largest,which was 29.66×10~4 yuan and36.92×10~4 yuan,respectively.Which was higher than that of conventional chemical fertilizer treatment.The output value per hectare of the biogas slurry treatment increased significantly compared with the water treatment,and the increase of economic output value per hectare reached 1.36~2.45×10~4 yuan and 1.86~4.31×10~4yuan.The results of winter and spring tomato quality showed that the titratable acidity of the fruits showed T5>T1>T2>T4>CF>T3>CK,while the soluble sugar,vitamin C,soluble protein,soluble solids content of the fruits and the hardness shows the trend of T1>T5>T2>T4>CF>T3>CK,which indicates that the quality of tomato fruit can also be improved by applying biogas slurry.(5)While the water use efficiency of tomato in winter and spring was inconsistent with the yield per plant,which shows the trend of T4>T1>T2>CF>T3>CK>T5.The production efficiency of nitrogen,phosphorus,and potassium in different ratios of biogas slurry is expressed by calculating the agronomy utilization rate of nitrogen,phosphorus,and potassium in biogas slurry.The results showed that the nitrogen,phosphorus and potassium agronomic efficiency of tomatoes in winter and spring showed a trend of T2>T1>T3>T4>T5>CF.Comprehensive tomato quality analysis,water use efficiency and nutrient agronomic utilization analysis,economic benefit analysis,and through the establishment of a multi-level and multi-objective comprehensive evaluation model based on information entropy theory,It can be concluded that the degree of decision making in T1 treatment is significantly higher than that in other treatments.Therefore,scientific and efficient management of biogas slurry ratio and irrigation amount based on T1 can achieve high yield and good quality and high water and fertilizer use efficiency.(6)The change trend of soil water content in the root zone of tomato during the two seasons of winter and spring under different biogas slurry ratio and irrigation volume is similar to that of time,that is,seedling stage>fruiting period>fruit enlargement stage>fruit mature stage.At seedling stage,soil moisture content increased in the root zone,and reached the highest point of water content in the whole growth period.After that,all treatments showed a decreasing trend.(7)The changes of total nitrogen,total phosphorus and total potassium in soils of tomato in winter and spring showed that the application of biogas slurry treatment could increase total nitrogen,total phosphorus and total potassium in soil and total nitrogen and total phosphorus in soil.The surplus of total potassium content increased with the increase of the ratio of biogas slurry and the amount of irrigation.