Adaptation of crop management to water-limited environments

Farmers must combine various crop management strategies to cope with water deficit resulting from soil, weather or limited irrigation: drought escape, avoidance or tolerance, crop rationing, irrigation (supplemental, deficit). These strategies can be translated into six objectives: (i) increasing soil stored water at plant sowing, (ii) increasing soil water extraction, (iii) reducing the contribution of soil evaporation to total water-use, (iv) optimizing the seasonal water use pattern between pre- and post-anthesis, (v) tolerate water stress and recover after stress alleviation, and (vi) irrigate at the most-sensitive growth phases. To reach these objectives, tactical decisions concern soil tillage, type of crop and cultivar, sowing date and density, N fertilization, irrigation timing, amount and frequency. Flexible crop management systems based on decision rules should be preferred to the recommendation of fixed packages of techniques. Timing, intensity, and predictability of drought (intermittent, terminal) are important features for choosing the cropping alternatives. Simulation models may help the farmer to select best-bet management options on the basis of historical long-term weather records. Simple soil and plant indicators associated with real-time decision support systems should be developed to revise the initial management plan by integrating in-season weather information.