Suitable inflow rate and furrow length for simplified surge flow irrigation     

Onishi  Junya  Ikeura  Hiroshi  Paluashova  Gaukhar K.  Shirokova  Yulia I.  Kitamura  Yoshinobu  Fujimaki  Haruyuki 《Paddy and Water Environment》2019,17(2):185-193

Paddy and Water Environment - In the arid lands covering Uzbekistan, furrow irrigation with low application efficiency is still widely used due to a lack of funds and shortage of labor. To save...  相似文献   

Use of Electrical Conductivity Instead of Soluble Salts for Soil Salinity Monitoring in Central Asia   总被引：6，自引：1，他引：5  

Y. Shirokova  I. Forkutsa  N. Sharafutdinova 《Irrigation and Drainage Systems》2000,14(3):199-206

The USSR classifications of soil salinity used in Central Asiawas based on laboratory measurement of the total dissolved(toxic) salts or the chloride ion concentration in the soil waterextracts (soil:water = 1:5). Current practices, however, startto differ between the republics because of different levels ofacceptance of international literature. This change in practiceis triggered partly by the cost of the laboratory measurements.The use of different methods next to each other affects thereliability of information on salinity. This paper promotes theused of the UC of a 1:1 soil-water suspension was found to givethe best fit to the soil extract with leaching of calcium andsulfate ions. The cost of data collection is significantly lowerthan that of the 1:5 extract.  相似文献   

Modeling irrigated cotton with shallow groundwater in the Aral Sea Basin of Uzbekistan: I. Water dynamics   总被引：4，自引：3，他引：1  

I. Forkutsa  Rolf Sommer  Y. I. Shirokova  J. P. A. Lamers  K. Kienzler  B. Tischbein  C. Martius  P. L. G. Vlek 《Irrigation Science》2009,27(4):331-346

In Khorezm, a region located in the Aral Sea basin of Uzbekistan, water use for irrigation of predominantly cotton is high whereas water use efficiency is low. To quantify the seasonal water and salt balance, water application, crop growth, soil water, and groundwater dynamics were studied on a sandy, sandy loam and loamy cotton field in the years 2003 and 2005. To simulate and quantify improved management strategies and update irrigation standards, the soil water model Hydrus-1D was applied. Results showed that shallow groundwater contributed a substantial share (up to 399 mm) to actual evapotranspiration of cotton (estimated at 488–727 mm), which alleviated water stress in response to suboptimal quantities of water applied for irrigation, but enhanced concurrently secondary soil salinization. Thus, pre-season salt leaching becomes a necessity. Nevertheless, as long as farmers face high uncertainty in irrigation water supply, maintaining shallow groundwater tables can be considered as a safety-net against unreliable water delivery. Simulations showed that in 2003 around 200 mm would have been sufficient during pre-season leaching, whereas up to 300 mm of water was applied in reality amounting to an overuse of almost 33%. Using some of this water during the irrigation season would have alleviated season crop-water stress such as in June 2003. Management strategy analyses revealed that crop water uptake would only marginally benefit from a permanent crop residue layer, often recommended as part of conservation agriculture. Such a mulch layer, however, would substantially reduce soil evaporation, capillary rise of groundwater, and consequently secondary soil salinization. The simulations furthermore demonstrated that not relying on the contribution of shallow groundwater to satisfy crop water demand is possible by implementing timely and soil-specific irrigation scheduling. Water use would then not be higher than the current Uzbek irrigation standards. It is argued that if furrow irrigation is to be continued, pure sandy soils, which constitute <5% of the agricultural soils in Khorezm, are best to be taken out of annual cotton production.  相似文献   

Modeling irrigated cotton with shallow groundwater in the Aral Sea Basin of Uzbekistan: II. Soil salinity dynamics   总被引：2，自引：1，他引：1  

I. Forkutsa  Rolf Sommer  Y. I. Shirokova  J. P. A. Lamers  K. Kienzler  B. Tischbein  C. Martius  P. L. G. Vlek 《Irrigation Science》2009,27(4):319-330

Years of ill-managed irrigation have triggered secondary soil salinization in the Khorezm region of Uzbekistan located in the Aral Sea basin. To assess the magnitude and dynamics of secondary soil salinization, to quantify improved management strategies and to derive updated irrigation standards, the soil water model Hydrus-1D was used. Water and soil salinity dynamics in three cotton fields with different soil textures were monitored and simulated for the years 2003 and 2005. Until now in Khorezm, overall soil salinity could only be controlled by pre-season salt leaching using high amounts of water. This water, however, may not be available anymore in the near future because of global climate change and shrinking fresh water resources. Simulations confirmed that the present leaching practice is barely effective. At two out of the three locations within a sandy loam field, leaching did not remove salts from the 2 m profile. Instead, salts were only shifted from the upper (0–0.8 m) to the lower (0.8–2 m) soil layer. Strong groundwater contribution to evapotranspiration triggered secondary (re)-salinization of the topsoil during the cropping season. As a consequence, salt amounts in the top 0.8 m of soil increased from 9 to 22 Mg ha⁻¹ in the field with loamy texture, and from 4 to 12 Mg ha⁻¹ in the field with sandy texture. Management strategy analyses revealed that reducing soil evaporation by a surface residue layer would notably decrease secondary soil salinization. Here, owing to the reduced capillary rise of groundwater, post-season salt contents of the three fields were reduced by between 12 and 19% when compared with residue-free conditions. Even more effective would be improving the efficiency of the drainage system so as to lower the groundwater table. This would require a revision of the current irrigation management schemes, but could, as simulations revealed, reduce the post-season salt content in the 2 m soil profile of the three fields by between 36 and 59% when compared with unaltered conditions. For the revised irrigation management in total not more water than already foreseen by national irrigation recommendations would be needed. Increasing leaching and irrigation efficiency would help sustaining the present cotton production levels while reducing future leaching demands.  相似文献