Water Re-Use Project

Water-saving Strategies in Irrigated Agriculture.
The Analysis of Water Re-Use Project Result
The purpose of the project “Water Re-Use” is to test ways of water- and soil-saving in conditions of irrigated agriculture and to provide preliminary recommendations for the region.
Ukraine is climatically predisposed to application of irrigation. However, on the territory of Ukraine there are few water sources for irrigation. Therefore, saving water and replacement of fresh water with sewage becomes an urgent problem.
     The Ukrainian researchers participated in an international research European project where scientists from different countries tested comprehensible strategies in different climatic and economic situations. Besides, there were collected opinions of experts, business executives, officials, policy makers, and other professionals so as to formulate a scientific and public position concerning conventional and recommended strategies in irrigated agriculture.
Urgency of search for new in irrigation strategies for Ukraine

1) Droughty climate throughout a significant part of the country

     40 % of Ukrainian territory is a Steppe with a very droughty climate, 35 % being Forest-Steppe with an insufficient level of natural humidifying. The southern Dry Steppe, south of Kherson region and northern part of the Crimea, with the humidity factor (precipitation to evaporation ratio) of below 0.25, in opinion of some researchers, is considered as a semi-desert zone.
     Climate aridization is a new factor which increases deficiency of moisture for plants. While for the previous 120 years of supervision there were registered 31 droughty year, during the last 15 years there were 7 droughty ones.  
2) Poor water supply of Ukrainian territory

     In  Ukraine there are yearly formed about 1000 m3 of drain per capita of population, which is significantly lower of the critical water supply, that is 1700 m3  (data of the European Economic Commission of the United Nations).
     Without additional humidification in the Steppe zone and in a significant part of Forest-Steppe zone efficient cultivation of agricultural plants, especially moisture-loving cultures, is impossible.
Strategy 1.  Use of purified waste water for irrigation as an the important source of reducing deficiency of water for agricultural crops in Ukraine
     Irrigated agriculture is an important and developed branch of agricultural production in Ukraine.
     By 1990 the area of the irrigated land was over 2.5 million hectares, including that irrigated by waste water and was over 100,000 hectares.
     There had been developed an infrastructure of irrigated agriculture, including designing and construction of irrigating systems, manufacture of technical equipment for irrigation and a network of regional laboratories for monitoring the irrigated land. Around large industrial cities (Kiev, Kharkiv, Odessa, Mariupol, etc.) there developed systems for irrigation with municipal and other waste water. In the following years, owing to various social and economic reasons, the areas of the irrigated land began to be reduced, and irrigation by waste water broke up in completely.

     The research showed, that watering with waste municipal waters of Kharkiv and, especially, with sewage from a pig-breeding complex, enriched by mobile nutrients, was very effective. It is important to emphasize, that a high efficiency of such irrigation was observed in conditions of Forest-Steppe where the need for additional humidifying is insignificant, and at cultivation of cultures with moderate need of water.
     The research was conducted within 4 years. The quality of vegetation and soil properties in the variants watered by sewage did not differ from the control variant with irrigation by fresh water.
     Thus, watering with sewage under a careful control of the composition of irrigation water and soil properties is practicable way to increase the efficiency of agriculture and recycling of drains.
     On the basis of the results of research and taking into account the previous research our proposals to renew irrigation by sewage in Ukraine can be considered grounded.
Field experiments with irrigation
Strategy 2. Soil and water saving as resent trends in improving irrigated agriculture in Ukraine

     The results obtained helped us to ground our proposals as to improving the theory and practice of irrigated agriculture in Ukraine. Conceptual positions are as follows:

     Requirements to irrigation:
- Time of supplying the water needs to be coordinated with the requirements of the culture itself;
- The volume of irrigation water needs to be coordinated with actual water capacity of the root soil layer;
- Depth of the humidified layer needs to be coordinated with the development of root system of plants.

     Task for meliorator:
- To provide minimal losses of water at irrigation;
- To provide minimal destruction of soil structure in the surface layer of soil.

Ways of achievement of conceptual positions of strategy 2:
- mulching the soil surface;
- minimization of depth of a settlement irrigation layer, especially at carrying out the 1-st and the 2-nd watering;
- minimization of ascending losses of moisture by shifting watering hours to a lower evapotranspiration times of the day;
- minimization of descending losses of moisture by way of eliminating preferential flows of moisture (watering should be without head);
- calculation of actual water-capacity of a watered layer by the parameters of soil bulk density and humidity, measured in an on-line mode, instead of on reference book;
- synchronization of irrigation norms with the depth of plant roots development;
- synchronization of watering time with the soil water penetration.
In field experiments with waste water
 Relative evapotranspiration for a day of June 26, 2009
Changes in the soil humidity (2006-2008): (1) Municipal waste water, Kharkiv, UA; (2) Waste water from a pig-breeding complex, Grakovo, UA; (3) Fresh water

Strategy 2 is aimed at overcoming the chronic drawbacks of existing practices of irrigated agriculture in Ukraine: excessive watering, soil degradation (flooding, secondary salinization, alkalinisation, infringement of structurization, overcompaction of superficial layer) and absence of control of the layer to be humidified before watering.
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