Features of forming the salt balance in rice fields with various parameters and designs of the Danube rice irrigation systems

Abstract

Ecological-reclamation state of rice irrigation systems harvest of cultivated crops determined by a number of factors, including natural (soil, topographical, hydrogeological, climatic factors) and technological (irrigation norm, designs and parameters of irrigation and drainage networks, etc.) factors. One of the main factors influencing the formation of rice yield which is traditionally grown by flooding technology is the efficiency of the rice irrigation system’s design. Construction features of irrigation fields and their parameters (distances between the drains, depth of the drainage network) affect the intensity of the processes of salinization of soils and groundwater. Analysis of the components of salt balances of rice fields with different parameters and designs on example of the Danube rice irrigation systems showed that fields with the distances between the drains from 200 to 250 m have significant advantages over Krasnodar-type fields with the same parameters and over fields with 500 m distance between the drains creating optimal salt regime for rice and, accordingly, obtaining higher yields of rice. As on the card-checks with drainage with the distances between the drains 500 m uniform desalinization of soils on all area cannot be reached and yield of rice on them is close to 20 c/ha such card-checks with drainage must be converted into card-checks with drainage with the distances between the drains 250 m.

Formation of a Favorable Filtration Regime of Soils in Saline Areas of the Danube Delta Rice Irrigation Systems

“…This value accounts for up to 50% of the consumable portion of the water balance. In our analysis, which is grounded in both our findings and the outcomes of previous filtration studies (Turchenuk et al 2016(Turchenuk et al , 2017, we propose that, for the establishment of favorable water-air and salt regimes in the soils of the aeration zone during the rice growing season, the intensity of filtration should be moderately low and consistent across the irrigation check area. Moreover, the filtration process should be actively managed.…”

“…Field investigations conducted by our team and other researchers (Turchenuk et al 2016(Turchenuk et al , 2017 in the rice systems of the Danube Delta reveal specific characteristics in the flow of filtration streams on irrigation cards during the maintenance of the water layer. A zone of groundwater buckling is formed along the irrigation canals, and a stagnant zone develops in the center of the check.…”

“…The assessment of the drainage system's effectiveness in the rice system, as outlined by Goncharov (1969), Mendus et al (2007), and Turchenuk et al (2016), revealed that the drainage implemented in the 1960s, following the design standards of that era, falls short of providing adequate drainage for rice fields. This inadequacy stands as a significant factor contributing to the unsatisfactory ecological reclamation state and the decline in yields of both rice and the associated crops in the rice rotation.…”

“…In light of this, we can infer that during the rice growing season, the rate of vertical filtration in the upper soil layer within the entire rice check area should be maintained within the range of 10 to 12 mm/day (Turchenuk et al 2016(Turchenuk et al , 2017. However, achieving uniform drainage across the entire rice field under the current designs of rice cards and drainage parameters is deemed unattainable.…”

“…Maintaining supported water levels should be implemented in card drainage canals located within the rice field from the re-flooding of rice fields after germination until the rice reaches maturity. The establishment of a supported water level is crucial not only for reducing filtration losses but also for enhancing the stability of drainage canals (Turchenuk et al 2016).…”