The effect of crop and climate factors on the radiation balance of an irrigated maize crop.
Loss of short-wave radiation by reflection from an irrigated maize crop grown for forage averaged 0.18 of the incident total short-wave radiation received during the growing season. This coefficient (albedo) varied by 15% during the growing season and was positively correlated with crop LAI. Diurnal changes in albedo were greater and were negatively correlated with solar elevation, although the arrangement of leaf area within the crop appeared to affect the albedo to a minor extent. Mean albedo agreed well with other measurements for maize. Net long-wave radiation loss from the crop averaged 0.35 of the incident total short-wave radiation received during the growing season. Seasonal variation in this component was small, but diurnal variation averaged 20%. The diurnal variation in downward long-wave flux from the sky was somewhat greater than that of upward flux from the crop surface. The size of the long-wave component was larger than previously published values for maize, but agreed well with values for other crop surfaces.-R.B.