Effect Of Biochar With Bio-Organic Fertilizer On Soil Physicochemical Properties And Small Chinese Cabbage Growth In Newly Reclaimed Lands

Newly reclaimed land,as a potential arable resource,suffers from soil erosion and weak fertility.Improving newly reclaimed land can increase the area of arable land,improve its quality and provide a guarantee for the sustainable agricultural development.In recent years,biochar and bio-organic fertilizer have been widely used for soil amelioration.Therefore,this study investigates the effects of biochar with bio-organic fertilizer on the physical and chemical properties of the soil and small chinese cabbage growth in newly reclaimed land based on indoor soil column simulation experiment,culture experiment and potting experiment.The soil column trial was set up with no biochar as control(CK),biochar species(maize straw biochar A,rice husk biochar B)and application amount(2%,4%,8%)for a total of 7 treatments;The culture experiment was carried out without the addition of bio-organic fertilizer as a control,and seven bio-organic fertilizer applications(1%,2%,3%,4%,5%,6%,7%)were set up in a mixed culture with soil,for a total of eight treatments;The pot experiment was set up with three biochar levels(B0,B1,B2)and two fertilizer levels(compound fertilizer Fc and bio-organic fertilizer FT at the same 150 mg/kg of nitrogen),for a total of six treatments.The following conclusions of the study were obtained:(1)In the soil column infiltration experiment,except for treatment B2,the addition of biochar slowed down the infiltration of soil moisture in the newly reclaimed land,increased the infiltration time,and reduced the migration distance,cumulative infiltration and initial infiltration rate of wetting fronts at the same time.The effect of maize straw biochar on slowing soil water infiltration was better than that of rice husk biochar.The effect of delayed water infiltration increased with increasing application amounts of maize straw biochar,while the delayed effect of water infiltration was strongest with medium application amounts of rice husk biochar.(2)In the soil column evaporation experiment,the effect of different species and application amounts of biochar on the evaporation process of the newly reclaimed soils varied.The addition of biochar increased the initial daily evapotranspiration intensity.The cumulative evapotranspiration and daily evapotranspiration intensity increased as the amount of maize straw biochar applied increased,with medium and high application amounts of maize straw biochar promoting soil water evapotranspiration,while low application amounts did the contrary.The cumulative evapotranspiration and daily evapotranspiration intensity decreased as the amount of rice husk biochar applied increased,and the medium to high application rate of rice husk biochar could significantly restrain soil water evaporation.(3)The results of the soil cultivation experiment show that the application of bio-organic fertilizer helps to improve the physical structure of the soil in the newly reclaimed land and enhances soil fertility.As the amount of bio-organic fertilizer applied increases,the soil bulk density decreases and the porosity increases,reaching a significant level at an application amount of ≥4%.The organic matter,alkaline nitrogen,fast-acting phosphorus and fast-acting potassium content of the soil increased with the application of bio-organic fertilizer,reaching a significant level at ≥1%.With the increasing of time,there is a slight increase of soil alkaline nitrogen and fast-acting phosphorus content under the effect of bio-organic fertilizer.There is a good linear relationship between soil fertilizer content and the amount of bio-organic fertilizer applied,with higher application amounts improving soil fertility levels.(4)The results of the pot trials showed that a suitable amount of maize straw biochar with bio-organic fertilizer helped to improve the physical properties of the soil and enhance soil fertility in the newly reclaimed land.Biochar with bio-organic fertilizer raises soil temperature;high application amounts of biochar(B2FΤ compared to B0FΤ)increased soil water content under bioorganic fertilizer conditions.Under B0 and B1 conditions,the application of bio-organic fertilizers(compared to compound fertilizers)increased soil organic matter,while the opposite was true under B2 conditions;under B1 conditions,the application of bio-organic fertilizers(compared to compound fertilizers)increased soil alkaline soluble nitrogen,while under B0 and B2 conditions,on the contrary(5)The results of the pot experiment showed that the suitable amount of maize straw biochar with bio-organic fertilizer can effectively promote the growth of small chinese cabbage.At the time of harvest of small chinese cabbage,the B1FΤ treatment showed increases in plant height,stem thickness,leaf area index,dry matter accumulation,yield and cumulative irrigation respectively compared to the B0FC treatment;the application of biochar under bio-organic fertilizer conditions can promote the growth of small chinese cabbage.Compared with compound fertilizers,the application of bio-organic fertilizers reduced the intercellular carbon dioxide concentration of small chinese cabbage leaves and increased the transpiration rate,stomatal conductance and net photosynthetic rate of small chinese cabbage leaves;compared with B0 condition,low application amounts of biochar reduce intercellular carbon dioxide concentration,high application amounts increase intercellular carbon dioxide concentration,the application of biochar reduces transpiration rate,stomatal conductance and net photosynthetic rate,the higher the application amounts,the greater the reduction.(6)The results of the pot experiment showed that the suitable amount of maize straw biochar with bio-organic fertilizer can effectively improve the quality of small chinese cabbage and increase its nutritional value.The application of bio-organic fertilizers significantly increased the soluble protein,soluble sugar and total phenol content of small chinese cabbage compared to compound fertilizers.Compared with B0 condition,the application of biochar significantly increased the soluble protein content of small chinese cabbage.Under compound fertilizer conditions,low application amounts of biochar reduced the soluble sugar content of small chinese cabbage,high application amounts of biochar did the opposite,while under bioorganic fertilizer conditions,the soluble sugar of small chinese cabbage decreased as the application amount of biochar increased.The B2FT treatment of small chinese cabbage had the highest total phenol content.There was no risk of exceeding nitrite levels in all treatments of biochar with bio-organic fertilizer,and the freshness of the small chinese cabbage was above 85%.(7)The treatment of 6.85 t/hm2 of maize straw biochar with bio-organic fertilizer(B1FΤ)can effectively improve the physical and chemical properties of the soil in the newly reclaimed land,promote the growth of small chinese cabbage and improve the quality of small chinese cabbage,which is the recommended choice for rapidly increasing the productivity of farmland in newly reclaimed land.