Determination of irrigation depth for potato considering weather forecast and cost for water under a saline condition

抄録

We have presented a new scheme, “optimized irrigation”, in which irrigation depth is determined such that net income during each interval is maximized considering weather forecasts and the price of water using WASH_2D, numerical simulation models of water flow and solute transport in soils and crop growth. To evaluate whether the optimized irrigation is also able to restrict salinity stress without any intentional leaching, we carried out an irrigation experiment in a sandy field. Potato was grown in a greenhouse in Tottori, Japan, using a drip irrigation system whose emitter distance was 20 cm and lateral spacing was 60 cm. Seeds were sown on 3 September below each emitter. Three treatments were established: 1) irrigation with fresh water (F), 2) irrigation with 2 g/L of NaCl solution (C), 3) irrigation with 2 g/L of NaCl solution and irrigation depth was determined with the proposed scheme (O). “F” and “C” were irrigated with automated irrigation systems using soil moisture sensors. Leachings were carried on “C” out on 12 (10 mm) and 21 (16 mm) November. “F” received the lowest amount of water owing to zero leaching requirement while “O” and “C” received almost the same mount. Net income was calculated under a producer price of 0.5 $/kgFW of tuber and the price of saline water at 0.5 $/m³. Treatment O gained the as high net income as F, revealing the effectiveness of the proposed scheme.