17:15 〜 19:15
[AGE34-P03] Improvement of soil physical properties by adding polymer compounds
キーワード：soil aggregate、water holding capacity、hydraulic conductivity、polymer
Heavy rain and drought, which are said to be the effects of global warming and climate change, are predicted, and farmland and soil environments are facing major challenges as a production base. There is a risk of soil erosion in the event of heavy rain, and measures to mitigate this are required. In the event of drought, it may be possible to lengthen the cultivation period by increasing the water retention capacity of the soil. The formation and maintenance of soil aggregation has long been sought after in terms of the development of soil structure, and it is often seen as the ideal form. It is said that the inter-aggregate pores increase water permeability, while the intra-aggregate pores increase water retention. Although high-molecular-weight polymers have been used as a means of artificially increasing the degree of soil aggregation, these polymers have been used without much discussion of their characteristics as high-molecular-weight polymers. In this study, we added high-molecular-weight polymers to soils and investigated in detail how the physical properties of the soil changed.
We used masa soil, clay soil, and reddish-yellow soil in the experiments, and added polyvinyl alcohol, polyacrylamide, natural rubber latex, and cellulose nanofibers at a weight ratio of 1% each as the polymer compounds. We then examined the soil moisture characteristics, particle size distribution, permeability, and functional groups using FTIR. We used the centrifugal method to improve the reproducibility of the soil moisture characteristic curve. We also used a laser diffraction particle size distribution measurement device to improve the reproducibility of the particle size distribution.
As a result, aggregation was promoted in cellulose nanofibers and polyvinyl alcohol, but not in latex. With regard to soil water retention, the addition of polymer compounds improved water retention in all cases except for clay. The effect was particularly pronounced with cellulose nanofibers, but the effect was limited with latex. With regard to permeability, the permeability of all polymers improved except for reddish-yellow soil.
From the experiments so far, it appears that each polymer has its own characteristics, and in particular, there are differences in the degree of aggregation and water retention. Finally, when the functional groups were examined using FTIR, there were differences in the expression of hydrophobic and hydrophilic functional groups, and it was thought that this was at least creating differences in water retention. In fact, if there are OH or COOH groups, they may work in the same way as clay minerals, which have a negative charge and adsorb substances, but we were unable to reach a systematic understanding within the scope of this inspection. Further investigation was considered necessary.
We used masa soil, clay soil, and reddish-yellow soil in the experiments, and added polyvinyl alcohol, polyacrylamide, natural rubber latex, and cellulose nanofibers at a weight ratio of 1% each as the polymer compounds. We then examined the soil moisture characteristics, particle size distribution, permeability, and functional groups using FTIR. We used the centrifugal method to improve the reproducibility of the soil moisture characteristic curve. We also used a laser diffraction particle size distribution measurement device to improve the reproducibility of the particle size distribution.
As a result, aggregation was promoted in cellulose nanofibers and polyvinyl alcohol, but not in latex. With regard to soil water retention, the addition of polymer compounds improved water retention in all cases except for clay. The effect was particularly pronounced with cellulose nanofibers, but the effect was limited with latex. With regard to permeability, the permeability of all polymers improved except for reddish-yellow soil.
From the experiments so far, it appears that each polymer has its own characteristics, and in particular, there are differences in the degree of aggregation and water retention. Finally, when the functional groups were examined using FTIR, there were differences in the expression of hydrophobic and hydrophilic functional groups, and it was thought that this was at least creating differences in water retention. In fact, if there are OH or COOH groups, they may work in the same way as clay minerals, which have a negative charge and adsorb substances, but we were unable to reach a systematic understanding within the scope of this inspection. Further investigation was considered necessary.