Distribution characteristics and stability of soil aggregates as compounded by soft rock and sand under different planting years of corn in Mu Us sandy land in China

Field plot experiments of compound soil mixing with soft rock and sand with ratios of 1 : 1, 1 : 2 and 1 : 5 during 2010-2018 years of corn cultivation in Mu Us Sandy Land in china., was carried out to observe the change characteristics of composition, distribution and mean weight diameter (MWD) of compound soil water stable aggregate (WSA) under different corn planting years. The results showed that with the increase of planting years, the content of WSA in composite soils of three portions with a particle size of < 0.25 mm gradually decreased, and WSA with a particle size of > 0.25 mm showed a continuous increasing trend. The WSA with a particle size of 0.25 - 0.5 mm accounted high for the maximum ratio, which plays an important role in the agglomeration of the compound soil. After 9 years of planting, the MWD of 1 : 1, 1 : 2 and 1 : 5 compound soil WSA increased by 1.13, 1.85 and 1.58 times, respectively, and t 1:2 compound soil WSA with particle size > 0.25 mm and MWD increase at a faster rate, which lead to a higher soil agglomeration and stability. The interaction between the mixture ratio of soft rock to sand and the planting years of corn has a significant impact on the formation and stability of WSA in the compound soil. With the increase of planting years of corn, the agglomeration effect of compound soil in different proportions was found to enhance, and the development of soil structure improve continuously. Bangladesh J. Bot. 50(3): 917-923, 2021 (September) Special

Impact of Effective Microorganisms (EM) Application on the Physical Condition of Haplic Luvisol

The study set out to determine changes in the soil air-water properties, the water-stable aggregate share and organic carbon content as effects of a five-year application of effective microorganisms (EM-A). The hypothesis that long-term applied EM-A biopreparations have a positive effect on the soil physical condition has not been confirmed. Haplic Luvisols originating from silt were studied in a field experiment after EM-A biopreparation treatment. The soil samples with the natural structure preserved intact were collected three times each year. The properties of the soil determined in the study were: particle density, total organic carbon content, bulk density, total porosity, air capacity, air permeability, soil moisture at sampling, field water capacity, available water content, unavailable water content, and water-stable aggregate content. The ratio of field water capacity and total porosity (FC/TP) was calculated. It was found that EM-A application primarily leads to a decrease in the content of organic carbon and water-stable aggregates. This was an adverse effect. Total organic carbon (TOC) and water-stable aggregates proved to be very sensitive indicators for assessing the soil physical condition. However, changes in soil compaction and air–water properties did not show significant deterioration. Our research addresses the data gaps about EM application to soil.

Uniform fiber distribution in cold asphalt mixtures with viscous microdispersed bitumen

. In this article, the authors have solved the applied problem of uniform distribution of fiber fibers in cold asphalt concrete mix. The principal possibility of uniform distribution of reinforcing elements in the form of short fibers of basalt and polyacrylonitrile fibers in the volume of reinforced asphalt materials based on microdispersed bitumens has been established. The technology of introducing fiber into mixtures-semi-finished asphalt materials based on microdispersed bitumens has been developed. At an asphalt concrete plant, a suspension ("solution") of basalt fiber or fiber from polyacrylonitrile fibers of the required concentration is prepared in a water supply container. The most appropriate way to mix water with fiber in the flow container is bubbling with compressed air using a compressor, which is the standard equipment of an asphalt concrete plant. Any dispersed-reinforced asphalt materials based on microdispersed bitumen can be prepared using a fiber "solution". Bituminous suspension in conditions that exclude water evaporation (in sealed containers), as a result of spontaneous processes, tends to a stable aggregate state. The most stable aggregate state of the bituminous suspension is plastic. In the process of preparing a bituminous suspension, it is necessary to ensure that it is obtained in a plastic state (similar to plasticine). In the plastic state, the mixture will not delaminate not only during storage, but also during transportation.