: Saturated soil culture is one of the water saving techniques that can improve water productivity. However, it is either less implemented or adopted because it consumes more time and energy. Therefore, an experiment was conducted to determine the effective water depth that can keep soil moisture close to saturation for a commonly practiced irrigation interval, combined with a rainfall pattern for increasing water productivity. The design was a randomized complete block with three replications and four water treatments representing 120% (T120), 180% (T180), 240% (T240), and 300% (T300) of soil saturation or the application of 2, 3, 4 and 5 cm water depth. The results showed that the application of 3 cm was the effective depth. It decreased plant height, tiller number, chlorophyll content, and panicle number per hill by 12.37%, 20.84%, 7.59%, and 70.98%, respectively. The decrease of these parameters is followed by total recovery due to effective rainfall contribution, which led to low yield sacrifice (6% of reduction) and 40% of water saving. We argue that weekly application of a 3 cm water depth and matching crop needed-water period with the onset of rainfall may be implemented and recommended as suitable saturated soil culture practice for rice production in high water demand conditions.

Saturated soil irrigation (SSI) has been reported as a great technique that increases water productivity in fully irrigated rice cultivation. However, this technique should be employed in a dry prone area where rainfalls fail to fulfill rice water requirements and fill up reservoirs for sufficient irrigation. Therefore, an experiment was conducted to identify the most effective complementary irrigation that restores soil moisture to saturation and increases water productivity with fewer yield expenses. The study used a complete randomized blocks design with four replications and four soil saturation treatments: Sat_200% (farmer practice), Sat_160%, Sat_120%, and Sat_80%. In Sat_160%, Sat_120%, and Sat_80% irrigation was applied once a week in the absence of rainfall. In Sat_200%, water was daily applied except the day of rain. The results showed that reductions in soil saturation decreased plant height, tillers, and leaves number by 10%, 18%, and 14%, respectively. Yield and components were reduced between 26.09% and 4.8%. Weekly soil saturation at 120% exhibited greater irrigation productivity (0.69 kg/m³), rainwater productivity (1.02 kg/m³), and water-saving (90.53%) with less production penalty (5 × 10⁻³ kg/m³). We advocate that saturated soil irrigation should be recommended in the rainfed rice system as a drought mitigation measure in semi-arid conditions.

Although promoted as an alternative to secure rain-fed agriculture, supplementary irrigation cannot ensure sustainable food production, regardless of the rational and optimal use of organic matter. Therefore, an experiment was set up in a sandy loam soil (bulk density =1.55 g/cm³; field capacity =18%; wilting point=1.4%) to determine the optimal combination of irrigation depth and compost rate. The experimental design was a split plot with four replications. The main factor was the irrigation water depths, which represented 50%, 75%, and 100% of the tomato crop’s water requirement (2800 m³/ha/Irrigation). The second factor consisted of two compost rates: 5 t/ha (C5) and 10 t/ha (C10). Six combinations were tested: C10 + 100%, C10 + 75%, C10 + 50%, C5 + 100%, C5 + 75%, and C5 + 50%. Fertilizers (NPK 14-23-14 and Urea 46%) were applied at the recommended rates of 250 kg/ha and 150 kg/ha, respectively, at 15 and 35 days after transplanting. The adopted irrigation interval was 2 days. After transplanting, a constant water depth (DI 100%) was applied, and water treatments were initiated 15 days after transplanting. Water application was postponed to the next irrigation if rain occurred. The results showed that, in general under supplementary irrigation, the addition of compost increase growth parameters, yield and water use productivity. However, when water requirement is reduced by half this increase is not consistent. Indeed, the higher yield was induced by C5 + 75% treatment. The combination of C10 + 50% improved water productivity by 70%. Therefore, the combination of C10 + 50% should be recommended for the sustainable management of land and water resources.