Alternate Wetting and Drying in the Center of Portugal: Effects on Water and Rice Productivity and Contribution to Development

Abstract

Rice irrigation by continuous flooding is highly water demanding in comparison with most methods applied in the irrigation of other crops, due to a significant deep percolation and surface drainage of paddies. The pollution of water resources and methane emissions are other environmental problems of rice agroecosystems, which require effective agronomic changes to safeguard its sustainable production. To contribute to this solution, an experimental study of alternate wetting and drying flooding (AWD) was carried out in the Center of Portugal in farmer’s paddies, using the methodology of field irrigation evaluation. The AWD results showed that there is a relevant potential to save about 10% of irrigation water with a reduced yield impact, allowing an additional period of about 10 to 29 days of dry soil. The guidelines to promote the on-farm scale AWD automation were outlined, integrating multiple data sources, to get a safe control of soil water and crop productivity. The conclusions point out the advantages of a significant change in the irrigation procedures, the use of water level sensors to assess the right irrigation scheduling to manage the soil deficit and the mild crop stress during the dry periods, and the development of paddy irrigation supplies, to allow a safe and smart AWD.

A bibliometric analysis of scientific literature on alternate wetting and drying (AWD)

“…The economic sustainability of AWD adoption is also a growing focus of study (Alauddin et al 2020;Hao et al 2022;Poddar et al 2022). Moreover, AWD research is extending beyond traditional regions like Asia, the USA, and Australia to places like the Mediterranean basin (Monaco et al 2021;Gharsallah et al 2023;Gonçalves et al 2022;Gilardi et al 2023), where AWD is being evaluated as a viable technique to address local issues while maintaining traditional gravity irrigation systems.…”

Evaluation of the Microbiological Quality of Water in the Rice-Growing System of the Lis Valley, Portugal

“…The soils have a clay loam texture, with a typical proportion of 56% clay and 37% silt, the pH is about 7.0-7.4, organic carbon content is 2.6-2.8% and bulk density is about 1.25 g/cm 3 . The ground table level is 70-90 cm below the soil surface, with a saturation soil water content of 0.50-0.52 cm 3 /cm 3 [12].…”

A Remote-Sensing-Assisted Estimation of Water Use in Rice Paddy Fields: A Study on Lis Valley, Portugal

“…In terms of practical effects, this means that the dry period is almost non-existent, except for the time when herbicides are applied and when the harvest is close (usually between the last 22-25 days). The measurements of the inflow and outflow discharges in P1 were measured using automatic water level sensors, where the data were complemented with the measurement of the atmospheric pressure through a barometer located nearby (Table 1), following the methodology used by Gonçalves et al [50] (Figure 2a). The sensors were inserted into a water tube consisting of a PVC pipe and placed on soil at a 25 cm depth.…”

“…In the sowing of this rice, the farmer used a combination of "Luna", "Teti", and "Lusitano" seeds in varying amounts. To obtain the rice yield, 5 sampling points were chosen to spatially represent the entire P1 plot, crosswise, from which a 0.5 m 2 (100 cm × 50 cm) sample was taken, following the methodology used by Gonçalves et al [50] (Figure 2c) in a procedure that is commonly used in rice experimentation in Portugal. All the sampled plants were collected manually.…”

“…The variables measured were: air temperature, relative humidity, wind speed, wind direction, daily average incoming solar radiation, and precipitation. Adapted from [50].…”