The study dealt with the following issues:
- study of the efficiency of autumn-winter and spring leaching irrigation
under different leaching methods and rates to combat soil
salinization on the background of close horizontal drainage;- identification of the reclamation effect of leaching,
influence of the latter on soil desalinisation, irrigation
water saving and cotton yield.
According to
natural and economic characteristics this pilot plot is
typical for Central Fergana.
Lithology: light and medium loams. Soils are medium
saline. Chemical composition is chloride-sulphate. Water
table is 2,0-2,4 m. Net area of the plot is 153 ha.Irrigation network – concrete flumes with efficiency
of 0.92-0.95. Specific length of close horizontal drainage's
is 40 m/ha. Drain depth is 2,7-3,0 m, while drain spacing
is 280 m.
Pilot site was
rigged by means of measurement and accounting.
Field observations of water and salt transportation,
water-salt balance elements in aeration zone, groundwater
and irrigated lands were made by standard methods.It was established that for Central Fergana conditions
under relatively close to surface groundwater (1.5-2.2 m)
further soil desalinization may be achieved by means of
winter-spring recharge irrigations and leaching with rate
of 1.5-2.5 thousands m3/ha, as well as by vegetation
irrigations with norm of 950-1100 m3/ha, providing
at least 3-4 irrigations with norm of 3.5-4.0 thousands
m3/ha. Experiments showed that the best time
for recharge irrigation is March and for leaching - January
and February.
In view of technological
approach the best was leaching by checks where soil salinization
during the growing season is slower than by furrows. |
