Effect of exchangeable sodium percent on surface sealing
Abstract Laboratory studies were conducted to evaluate the effect of exchangeable sodium percent (ESP) on soil surface sealing and of surface sealing on infiltration and evaporation processes. Surface seals with hydraulic conductances 52.20 × 10 −3 , 49.20 × 10 −3 , 39.00 × 10 −3 , 33.00 × 10 −3 , and 17.91 × 10 −3 h −1 were attained on top of a sandy loam soil with ESP of 4 by placing a 5-mm layer of the same soil with ESP's 6, 10, 20, 30, and 60 respectively. Surface sealing increased with increasing ESP and appeared complete at ESP 30. Evaporation remained unaffected by the seals. Infiltration, however, was considerably reduced. Soil water profiles, which largely depended on the amount of infiltrated water, tended to become uniform. Equal moisture contents were also observed under evaporation.
Rainfall‐Induced Soil Surface Sealing: A Critical Review of Observations, Conceptual Models, and Solutions
Rainfall‐induced soil surface sealing can have severe agricultural, hydrological, and environmental effects. Seal formation is a complex phenomenon dominated by a wide variety of factors involving soil properties, rainfall characteristics, and flow conditions. It has been studied through extensive experimental investigations as well as simulation models. This study reviews some of the main issues, in terms of morphology, phenomenology, and both conceptual and empirical modeling approaches to improve our perception of the phenomenon and our ability to simulate its effects on flow processes. The effects of different factors on infiltration during seal formation and in sealed soil profiles are highlighted, including seal representation, soil and rainfall properties, and field heterogeneity. New research opportunities toward a generalized formulation of the processes involved in soil sealing and a reliable quantitative prediction of its effects on flow processes are identified. These are related mainly to the ability to quantify and predict the relationships between soil hydraulic properties and physical, chemical, and biological factors that affect the soil resistance to destruction.
A rainfall simulator for laboratory studies on crusting
An assembly for simulating rain of varying intensities has been designed and set up. Hypodermic needles of 20 gauge were used for producing drops. The intensity of rains ranged from 2.9 to 11.3 cm/h and the uniformity coefficient varied from 95.9 to 99.8%. Drop size was relatively smaller than that present in the natural rain of same intensity.