Effects Of Combined Application Of Biogas Slurry And Biochar On Fine Root Biomass,Morphology And Carbon And Nitrogen Content Of Poplar Plantation

With global energy and environmental crisis,the effective use of resources is one of important issues.Because biogas slurry is an organic fertilizer with rich in nutrients,and biochar is a good soil modifier,biogas slurry and biochar combined application can achieve complementary advantage to improve the nutrient utilization rate.The application of biogas slurry and biochar to poplar plantation not only may take the effective utilization of agricultural and forestry wastes,but also to provide a new way to maintain soil fertility in poplar plantation.Soil fine root is a vital organ of the tree absorbing water and nutrients.We have conducted the experiment to examine the effects of application of biogas slurry mixed with the biochar on soil fine roots in the poplar plantation,and to provide the ways of application of biogas slurry with biochar,and sustainability management of poplar plantation as well.In the poplar plantation in north Jiangsu province,four application levels of biogas slurry of 0,125,250 and 375 m³·hm^-2 were set by random block design,and four application levels of biochar of 0,40,80 and 120t·hm^-22 were set in each application level of biogas slurry,respectively.The results were as follows.?1?In April,July,October and December,the interaction between biogas slurry and biochar was not significant?P>0.05?,but both significantly reduced the total biomass of fine roots in the 0-60cm soil layer?P<0.05?.Biogas slurry and biochar have different effects on the biomass of fine roots in different layers and grades:For the 0-20 cm soil layer,biogas slurry and biochar significantly reduced the biomass of fine roots and root biomass of grade 1-5 in this layer in April,July,October and December?P<0.05?.For the 20-40 cm soil layer,in April,biogas slurry and biochar both significantly reduced the biomass of fine roots in this layer,and biogas slurry significantly reduced the biomass of fine roots of grade1-3 in this layer,and biochar significantly reduced the biomass of fine roots of grade 2-5 in this layer?P<0.05?.In July,biogas slurry significantly reduced the biomass of fine roots in this layer,and biogas slurry significantly reduced the biomass of fine roots of grades 1-5in this layer,and biochar significantly reduced the biomass of fine roots of grades 1,3,4,and 5 in this layer?P<0.05?.In October and December,biogas slurry and biochar had no significant effect on the biomass of fine roots in this layer?P>0.05?,but biogas slurry and biochar both significantly reduced the biomass of roots of grade 1-3 in this layer?P<0.05?.For the 40-60 cm soil layer,in April,biogas slurry and biochar had no significant effect on the biomass of fine roots in this layer?P>0.05?,but biogas slurry significantly reduced the biomass of fine roots of grade 1,2 in this layer,and biochar significantly reduced the biomass of fine roots of grade 2 in this layer?P<0.05?.In July,biogas slurry and biochar had no significant effect on the biomass of fine roots of this layer?P>0.05?,but biogas slurry significantly reduced the biomass of fine roots of grade 1 in this layer,and biochar significantly reduced the biomass of fine roots of grade 1,2 in this layer?P<0.05?.In October,biogas slurry and biochar had no significant effect on the biomass of fine roots in this layer?P>0.05?,but biogas slurry significantly reduced the biomass of fine roots of grade 1,2 in this layer,and biochar significantly reduced the biomass of fine roots of grade 1in this layer?P<0.05?.In December,the effect of biogas slurry and biochar on the biomass of fine roots in this layer was not significant?P>0.05?,but both biogas slurry and biochar significantly reduced the biomass of fine roots of grade 1,2 in this layer.?2?Biogas slurry and biochar have different influences on the average diameter of 1-5grade fine roots in different soil layers:For the 0-20 cm soil layer,in April and October,biogas slurry and biochar significantly reduced the average diameter of fine roots of grade 1,2 in this layer?P<0.05?.In July and December,biogas slurry significantly reduced the average diameter of fine roots of grade 1-3 in this layer,and biochar significantly reduced the average diameter of fine roots of grade 1,2 in this layer?P<0.05?.For the 20-40 cm and 40-60 cm soil layers,biogas slurry and biochar had no significant effect on the average diameter of fine roots of grade 1-5?P>0.05?.Biogas slurry and biochar have different influences on the average length of 1-5 grade fine roots in different soil layers:For the 0-20 cm soil layer,in April,the biogas slurry significantly reduced the average length of fine roots of grade 1-5 roots in the layer?P<0.05?.In July,the biogas slurry significantly reduced the average length of fine roots of grade 1-4 in this layer?P<0.05?.In October,the biogas slurry significantly reduced the average length of fine roots of grade 1,2 in this layer?P<0.05?.In December,the influence of biogas slurry and biochar on the average length of fine roots of grade 1-5 grades in this layer was not significant?P>0.05?.For the 20-40 cm layer,in April,biogas slurry significantly reduced the average length of fine roots of grade 1,2 in this layer?P<0.05?.In July,the biogas slurry significantly reduced the average length of fine roots of grade 1-4 in this layer?P<0.05?.In October,the biogas slurry significantly reduced the average length of fine roots of grade 1-5 in this layer?P<0.05?.In December,the influence of biogas slurry and biochar on the average length of fine roots of grade 1-5 in this layer was not significant?P>0.05?.For the 40-60 cm soil layer,in April,the biogas slurry significantly reduced the average length of fine roots of grade 1-4 in this layer?P<0.05?.In July and October,biogas slurry significantly reduced the average length of fine roots of grade 1-3 in this layer?P<0.05?.In December,the influence of biogas slurry and biochar on the average length of fine roots of grade 1-5 in this layer was not significant?P>0.05?.Biogas slurry and biochar have different influences on the s pecific root length of 1-5grade fine roots in different soil layers:For the 0-20 cm soil layer,in April,the biogas slurry significantly reduced the the specific root length of fine roots of grade 1-5 in this layer,and the biochar significantly reduced the the specific root length of fine roots of grade 1,2 in this layer?P<0.05?.In July,biogas slurry significantly reduced the specific root length of fine roots of grade 1-5,and biochar significantly reduced the specific root length of fine roots of grade 2,3?P<0.05?.In October,biogas slurry significantly reduced the specific root length of fine roots of grade 1-5,and biochar significantly reduced the specific root length of fine roots of grade 1,4,and 5?P<0.05?.In December,biogas slurry significantly reduced the specific root length of fine roots of grade 1-5,and biochar significantly reduced the specific root length of fine roots of grade 1-4?P<0.05?.For the 20-40 cm soil layer,in April,biogas slurry significantly reduced the specific root length of fine roots of grade 1-5,and biochar significantly reduced the specific root length of fine roots of grade 1,2?P<0.05?.In July,the biogas slurry significantly reduced the specific root length of fine roots of grade 1-5,and the biochar significantly reduced the specific root length of fine roots of grade 1,3,and 4?P>0.05?.In October,biogas slurry significantly reduced the specific root length of fine roots of grade 1-5,and biochar significantly reduced the specific root length of fine roots of grade 1,2?P<0.05?.In December,the biogas slurry significantly reduced the specific root length of fine roots of grade 1-4?P<0.05?.For the 40-60 cm soil layer,in April,biogas slurry significantly reduced the specific root length of fine roots of grade 1-4,and biochar significantly reduced the specific root length of fine roots of grade 2?P<0.05?.In July,the biogas slurry significantly reduced the specific root length of fine roots of grade 1,2,4,and 5?P<0.05?.In October,biogas slurry significantly reduced the specific root length of fine roots of grade 1,2,4 and 5,and biochar significantly reduced the specific root length of fine roots of grade 2?P<0.05?.In December,biogas slurry significantly reduced the specific root length of fine roots of grade 1,2,and 4,and biochar significantly reduced the specific root length of fine roots of grade 2?P<0.05?.?3?In April,July,October and December,the interaction between biogas slurry and biochar was not significant?P>0.05?,but the C content of fine roots of grade 1-5 was significantly reduced?P<0.05?.The interaction between biogas slurry and biochar on N content of fine roots at all grades was not significant?P>0.05?.In April,the N content of fine roots of grade 1-5 was significantly reduced in biogas slurry,and the N content of fine roots of grade 1 and 2 was significantly reduced in biochar?P<0.05?.In July,biogas slurry significantly reduced the N content of fine roots of grade 1-5,and biochar significantly reduced the N content of fine roots of grade 1,2 and 4?P<0.05?.In October and December,the N content of fine roots of grade 1-5 was significantly reduced in biogas slurry,and the N content of fine roots of grade 1-3 was significantly reduced in biochar?P<0.05?.In summary,biogas slurry combined with biochar has a significant effect on the biomass,morphological characteristics and carbon and nitrogen content of fine roots at all grades?especially lower roots?of poplar plantation.Our results provide a scientific basis for us to understand the mechanism of biogas slurry combined with biochar to regulate fine root structure and function.