Impact of Soil Heat Flux on Water Use of Quinoa

       A field study was conducted in the winter season of 2017 at the Agricultural Experimental Station of Wadi Suder, south Sinai (D.R.C.), to evaluate the effect of soil organic matter and  applied irrigation water on soil thermal conductivity, soil heat flux consequently on soil evaporation , actual water evapotranspiration (ETa) and water use efficiency (WUE) of quinoa yield(chenopodium quinoa willd). Theoretical water evapotranspiration (ETo) was calculated for each treatment using Penman-Monteith equations. Water use efficiency (WUE) was calculated as a result of cumulative improvement for studied parameters. The results reveal that soil thermal conductivity increases by24, 26 and 65% as increasing of applied water, organic matter and their interaction, respectively. While, soil heat flux correlated significantly with all treatments and soil heat conductivity. Generally, the increases were 71, 86 and 232% for organic matter, applied water and inter action, respectively. Whereas, soil heat flux increase by 0.02 mj/m²/day as a result of increasing thermal conductivity by 9.33 cal/cm/s/^oc (each 1 cal/cm/s/^oc of thermal conductivity enhanced heat flux by 0.002 mj/m²/day). Evaporation from soil surface increase by 0.008 mm/day as heat flux increase by 0.021mjm^-2day, whilst, increasing soil heat flux (1mj/m²/day) resulted in decreasing Eta by 1.81m³/fed. Simultaneously data illustrates that increasing evaporation by 0.008mm/day led to decrease Eta by 8.92m³/fed. Thus, water use efficiency WUE increases spontaneously by (136%) and (119%) for seed and straw yield, as soil heat flux increased by 0.021mj/m²/day, respectively. From the aforementioned data, we advise by using irrigation treatment 80% coupled with 1% organic matter which save about 20% from main applied water this ratio will increase seed yield by 402kg (36%). Also, at drought condition the farmer can use irrigation treatment 60% whereas save about 39% (675m³) if it use under the same organic matter (1%) which could enhance seed yield by 27%.