Influence of Row Spacing and Straw Mulch on First Stage Drying

Abstract

Evaporation during first stage drying was measured with evaporation plates on the soil surface in grain sorghum plots with 25‐, 50‐, and 100‐cm row spacings, during several stages of grain sorghum [Sorghum bicolor (L.) Moench] development in 1972 and 1973. Evaporation during first stage drying was affected by row spacing, leaf area index (LAI), and soil shading. Both LAI and soil shading were related to row spacing and plant population. The more complete plant canopy of grain sorghum with narrow‐row spacing decreased penetration of radiant energy to the soil surface and reduced the evaporation rate of soil water during first stage drying. Evaporation was greatest during the early part of the season when shading was least and lowest during boot stage and pollination, when all leaves were fully expanded and provided maximum plant canopy and soil shading. Narrow‐row spacing established an earlier, and more complete plant canopy than conventional 100‐cm row spacing and shaded more of the soil surface from early vegetative growth to maturity. Soil surface shaded near solar noon was a better indicator of first stage evaporation beneath a canopy than LAI.The combined effect of a mulched surface and a plant canopy on reducing evaporation was the product of the fractional reduction in potential evaporation resulting from the plant canopy and the evaporation resulting from the mulched surface with no canopy cover. An empirical equation was developed from the evaporation data for use in calculating first stage evaporation as related to potential evaporation, fraction of the soil surface shaded, and mulch rate.

Quantifying and predicting soil water evaporation as influenced by runoff strip lengths and mulch cover

“…These values are in agreement with the finding of other authors (Todd et al, 1991;Adams et al, 1976), but suggested that effects of mulch and crop canopy shade were independent of each other under dryland production without water harvesting and under limited irrigation. Shading by maize canopy under dryland condition significantly reduced the Es by 0.5 and 0.3 mm d −1 and under limited irrigation by 0.6 and 0.7 mm d −1 for two consecutive seasons (Todd et al, 1991).…”

Modelling the impact of mulching the soil with plant remains on water regime formation, crop yield and energy costs in agricultural ecosystems

“…1b. The measurements were taken from literature (Bond and Willis, 1970;Adams et al, 1976) and obtained in our field experiments (Gusev et al, 1992).…”

Quantitative analysis of yield and soil water balance for summer maize on the piedmont of the North China Plain using AquaCrop

“…where CC is canopy cover, (1-CC*) is the adjusted fraction of the non-covered soil surface [69,70] ; Ke x is maximum soil evaporation coefficient for fully wet and non-shaded soil surface, the default value is 1.10 [71] ; Kr is the evaporation reduction coefficient; f K is a decline factor, the value of f K depends on the hydraulic properties of soil and can be used to calibrate Kr (Table 2), which takes a value of 4 [68] ; W rel is the relative water content of the soil layer through which water moves to the evaporating soil surface layer. When CC* = 0, E stage I = E 0 .…”