Soil Water Evaporation: Surface Residue Rate and Placement Effects

Abstract

Evaporation with time was measured from columns of originally wetted fine sandy loam soil subjected to uniform daily evaporative potential and treated with various rates of surface residue. During the initial constant rate drying stage, evaporation decreased with increasing residue rates. Conjunctively, the period of constant rate drying was appreciably lengthened with decreasing evaporation rates. After prolonged falling rate drying, cumulative evaporative losses were nearly equal irrespective of surface residue. It was hypothesized that during falling rate drying and with limited quantities of residue, total evaporation might be less if the residue were placed on less than the entire soil surface in concentrated zones. Utilizing the available data, calculated curves were constructed which supported the hypothesis. Additional