Characterizing Soil Physical Properties and Their Influence on Moisture Retention in Eastern Mau, Kenya

Abstract

The study was undertaken to determine site specific physical properties of soil in the plains of Eastern Mau Escarpment for the purposes of enhancing agricultural productivity. Soil physical characteristics are a function of soil moisture retention which has an important influence on agricultural productivity. Topography was found to be 1-1.65%. The soil profile of the mollic andosols was defined as; well drained, moderately deep with varied structure across the profile as supported by the trend of moisture content analysis down the profile which revealed that the moisture content variation was a third order quadratic function that increased with depth. It is characterized by coarse texture, low organic matter status, deep and well-drained profiles. The sieve analysis revealed that it is a rich gradation which refers to a sample of aggregate with a high proportion of particles of small sizes. The weighted means of soil fractions were 82.1, 2.7 and 15.2% for sand, silt and clay respectively. Bulk density, (BD), varied from 1.04-1.37 gcm^-3 within the top soil. The highest BD in the study profiles was found to occur between 20 and 40cm depths, suggesting the existence of a plough pan. Particle density ranged from 1.61 to 2.18gcm^-3. Mean particle density was 2gcm^-3 with high density particles dominating the top 20cm. The pF curves for samples from soil depths; 10, 20, 30, 40, 50 and 60 cm had unique SWCC though the soil texture was found to be similar in all sampled profiles. It was revealed that the plough pan layer retained more moisture than above and below it.

Keywords; mollic andosols, physical characteristics, rich gradation, plough pan