Analysis Of Reflection To Soil Particle Size Based On Multi-angular Measurements

The need of the use of modern technological tools to analyze and examine spatial phenomena in an ecological space requires attention.Soil,an integral part of the global ecosystem which forms the Earth’s uppermost layer,serves as home to plants,animals,and other living organisms needs to be continuously investigated to preserve its sustainability function.The soil structural parameters interaction with solar(light)energy produces one of the three(3):absorption,reflection,and transmittance.Of the three(3)reaction exhibits by soil parameters with their light energy interaction,reflection is of primary importance in remote sensing for analyzing and estimating inherent soil properties.Soil particle size serves as a coordinating element in soil’s structural parameters that dictates the interaction of a soil’s chemical and biological properties.The other soil parameters are housed in soil depending on the particle size distribution of the soil under investigation;this results in the variations in the degree of energy reflected by soil particle sizes.The BRF of soil surfaces fuel the estimation and assessment of soil properties in Remote Sensing to characterize,map,and classify soil resources for their effective and efficient utilization.This research analyzed the BRF from soil particle sizes measured at varied viewing angles.As soil surface reflection is a crucial element in environmental monitoring,assessment,and precision agriculture.This research shall contribute to interpreting and understanding of the complex interaction of light energy and its effects on soil parameters,particularly soil particle sizes,and how reflected energy measured from soil surfaces can influence current knowledge in soil’s effective classification and characterization.Three different types of soil samples were sieved for the study:two(2)of the soil samples thus the black soil and chestnut-cinnamon soil had 14 sieved particle sizes ranges in a descending order from 2mm-0.027mm and the aeolian sandy soil on the other hand had 6 sieved particle sizes ranging from 0.525mm0.075mm.All the measurements for each sample were taken in the visible and near infrared wavelength range using the Northeast Normal University Laboratory Goniospectrometer Systems(NENULGS).The Bidirectional Reflectance Factors(BRFs)was measured at varied viewing angles.The non-Lambertian phenomena of the soil surfaces BRF and ARF at selected wavelength were compared with earlier research to validate the accuracy of this study measurement.Also,the average BRF of each particle size were quantitatively analyzed in the visible and near infrared wavelength at the nadir direction to enable standardization of data detected from other angles.Furthermore,like earlier studies,the BRF of all the particle sizes measured for the study reflection peak at the backward scattering direction and the minimal reflection was in the forward scattering direction.Again,the multi-angular ARF relative difference was calculated for the 0.3mm particle sizes of all the 3 soil samples.It was observed that the maximum relative ARF difference were in the backward scattering direction and its minimal relative difference is recorded in the forward scattering.The maximum and minimal ARF relative difference was exhibited by the black soil particle sizes in both the visible and Near Infrared domain.Furthermore,the variations observed in the particle sizes of the three soil samples ARFs shows that soil surface anisotropic characteristics is one of the essential parameters in examining and analyzing changes of soil particle sizes.The soil samples effective particle sizes were correlated and estimated with the BRF at nadir and evaluated at all viewing angles.The results showed strong average linear R~2=0.84measured at all viewing angles for the aeolian sandy soil and fairly strong linear relation for the chestnut-cinnamon soil and a weak linear relation for the black soil(R~2=0.64:R~2=0.41respectively).The weak linear relation exhibited by the black soil is attributed mainly to its relatively high organic matter content.The aeolian sandy soil natural logarithm correlation coefficient(R~2)is the weakest.This weak relation is fueled based on the assumption of minimal particle size distribution of the aeolian sandy soil.The chestnut-cinnamon soil and black soil natural logarithm relations are strongest and strong respectively.The results shows that the volume of particle size distribution dictates the type of statistical tool to be employed for efficient quantitative examination of soil surfaces BRF.The methods employed for this study shows considerable contribution in helping to understand reflected light energy from different soil surfaces at varied viewing angles.It also showed that appropriate application of the method is vital for characterizing,mapping,and classifying soils to serve their effective purpose for efficient soil utilization.