Integrated Irrigation and Drainage Practices to Enhance Water Productivity and Reduce Pollution in a Rice Production System

Abstract

Water-saving irrigation and controlled drainage have been separately practised in many countries to increase water use efficiency and reduce non-point source pollution while maintaining crop yields. In a two-year field experiment in the Gaoyou Irrigation District of South China, water use, crop yield, and pollution loads were monitored in an integrated water-saving irrigation and controlled drainage (WSI-CD) system and an unregulated system. For both 2007 and 2008, irrigation water productivity (WP I ) and gross water productivity (WP G ) of the WSI-CD were 45.3 and 31.6% higher than those of the unregulated system. While evapotranspiration water productivity (WP ET ) of the WSI-CD was similar to or even less than that of the unregulated system, this indicated that a reduction in irrigation water did not cause water stress and the WSI-CD only reduced non-productive water use. In 2008, the amount of drainage water from WSI-CD (1956 m 3 ha -1 ) was far less than the unregulated system (4255 m 3 ha -1 ), and TN and TP loads were significantly reduced by 50.9 and 52.3%.The water-saving irrigation practice contributed to lower drainage potential, while the controlled drainage reduced irrigation requirements. The integrated WSI-CD practices seemed to have the desirable functions of water saving and pollutant reduction. RÉSUMÉ L'irrigation économe en eau et le drainage contrôlé ont été pratiqués séparément, dans de nombreux pays pour augmenter l'efficience d'utilisation de l'eau et réduire la pollution diffuse, tout en maintenant les rendements. Au cours d'une expérience de terrain de deux ans conduite dans le district d'irrigation Gaoyou en Chine du Sud, les lames d'eau, le rendement des cultures, et la pollution ont été suivis dans un système intégré d'économie d'eau d'irrigation et de pratiques de drainage contrôlé (WSI-CD) par comparaison avec un système non contrôlé. Pour 2007 et 2008, la productivité de l'eau d'irrigation (WPI) et la productivité de l'eau brute (GTP) du WSI-CD ont été de 45.3 et 31.6 % plus élevées que ceux du système non contrôlé. Alors que la productivité de l'eau d'évapotranspiration (WPET) du WSI-CD était semblable ou même inférieure à celle du système non contrôlé, ce qui indique que la réduction de l'eau d'irrigation n'a pas causé de stress hydrique et que le système contrôlé a seulement réduit la consommation d'eau non productive. En 2008, la lame d'eau drainée de WSI-CD (1956 m 3 ha -1 ) a été beaucoup moins moindre que le système non contrôlé (4255 m 3 ha -1 ), alors que les charges TN et de TP ont été significativement réduites de 50.9 et 52.3 %. Les pratiques d'irrigation économes en eau ont contribué à plus faible potentiel de drainage, tandis que le drainage contrôlé réduit les besoins en irrigation. Le système intégré d'économie d'eau et de drainage controlé semble avoir la double fonction d'économie d'eau et de réduction des polluants.

Further Understanding of the Impacts of Rainfall and Agricultural Management Practices on Nutrient Loss from Rice Paddies in a Monsoon Area

“…They also found that the loss of T-N and T-P decreased from 165.5 to 20.2 kg ha −1 for N and from 1.96 to 0.58 kg ha −1 for P by the reduction of irrigation. Peng et al (2012) also reported that water-saving irrigation (reduction of 20 to 40 % compared to the conventional irrigation) reduced loss of both N and P by around 35 %. Fig.…”

Biodiversity Conservation in Rice Paddies in China: Toward Ecological Sustainability

“…Since the 1990s, researchers have developed, tested and disseminated several water-saving irrigation techniques for rice cultivation, including controlled irrigation [40,41], intermittent irrigation [42,43], half-dry cultivation [44], filmed ground and dry cultivation [44], systems of alternate submergence-nonsubmergence [45] and alternate wetting and drying [46,47]. These methods share the absence of continuous standing water on the paddy field surface or soil moisture content lower than saturation; thus, the paddy field moisture conditions differ from those created by traditional flooding irrigation.…”

“…Irrigation water is also over used; thus, most of the applied fertilizers is flushed out of the fields and causes eutrophication of downstream water bodies [41]. We can control the downstream water bodies, and let some aquatic plants absorb the nutrients in the drainage.…”

Straw Application Strategy to Optimize Nutrient Release in a Southeastern China Rice Cropland

“…The soil pH (1:5 with H 2 O) was 6.5, and the concentrations of organic carbon, total N, and total P were 18.1, 1.2, and 1.1 g kg −1 , respectively [28]. The water level was maintained at 5-7 cm above the soil surface in the rice crops before the late tillering stage, and then drained for the control of non-productive tillering [38]. After about one week, the paddy field was re-flooded, kept alternately wet and dry, and then drained again two weeks before rice harvest.…”