• 
• Japanese
• 
• IETC's Focal Area
• Waste Management
• Publications & Tools
• Meetings & Workshops
• Global Partnership on Waste Management
• Water and Sanitation
• Publications & Tools
• Meetings & Workshops
• Resources
• Publications & Tools
• About IETC
• Background and History
• Director
• Activity Reports
• Supporting Foundations
• Contact Us

3.17 Irrigation With Diluted Liquid Manure

Technical Description

The basic principle of this technology is water recycling within a partially closed agricultural system. The liquid manure is diluted with surface water (in part, used to wash out the barnyard), use to irrigate the agricultural areas, and collected as a return flow from the fields for secondary use. Pig and cattle sheds can be designed and built to collect liquid and solid manure to permit these wastes to be flushed to a collection point where they can be used for irrigating grasslands, fodder fields, and vegetable growing areas. The volume of wastewater that can be collected from a 30 000 pig shed amounts to 120 000 m³/year. While it is technically feasible to reuse this entire volume, the reuse of water may be limited by the allowable fertilization rates for the lands being irrigated. For example, one particular pig operation is limited in its reuse by the amount of nitrogen in the wastewater (the allowable fertilization dose in this case is 300 kg N/ha).

The irrigation system at Limanti, Latvia, is an example of this type of agricultural reuse system. The system employs two stationary pumping stations, one of which is for pumping the liquid manure and the other is for pumping freshwater from the Daugava River. Smaller pumping stations are used for recycling the return flows to the manure collection reservoir. This collection reservoir is located within the drainage system of the irrigated area. All surface flows and drainage waters are gathered in this reservoir. The main piping conduits are 500 mm diameter steel pipes which deliver the water and manure to asbestoconcrete pipes ranging in diameter from 300 mm to 500 mm. The liquid manure is screened before being irrigated, and, should additional storage be required, temporary reservoirs for storing the diluted liquid manure within the fields may be constructed with plastic screens.

Extent of Use

This technology has been well used in Latvia since the early 1980s. More than 10 large pig farms, housing more than 10 000 pigs each, and almost 100 large cattle farms, with more than 400 cows each, have constructed this type of reuse system. This method is used in Latvia, Lithuania, and Russia.

Operation and Maintenance

Good meteorological information is required to prevent water-logging of the fields. Likewise, skilled agronomists are needed to determine appropriate manure application rates to provide adequate fertilization of crops and to minimize the potential for groundwater contamination by nitrates, etc. Skilled mechanics (two for running the pumping stations and 8 for operating the irrigation equipment, in two shifts) are also very important for the successful operation and maintenance of this type of system.

Level of Involvement

While this technology is generally implemented at the local farm level, monitoring and control by environmental authorities of groundwater, wells, soils, and surface waters, and by health authorities, to assure the quality of the produce, is often necessary.

Costs

The construction cost of this type of reuse system is about $10 000/ha, and the anticipated payback period is 6 to 8 years. Recurring irrigation costs are estimated to be about $1 000/year. The net improvement in crop yields through the use of liquid manure is approximately 200 centners of fodder per hectare. The water saving and environmental issues are additional benefits derived from the use of this technology, but are difficult to estimate.

Effectiveness of the Technology

Use of this technology has resulted in an harvest of grass of up to 600 centners/ha. The efficiency of the system is high, and additional environmental benefits and water savings occur. Agricultural production is increased by approximately 2 times, and the use of mineral fertilizers is decreased by more than 2 times. Further the total volume of freshwater used in irrigation is decreased from 3 m3/ha to a total of 2 m3/ha, 1.5 m³ of which is freshwater. This results in a savings of 50% in freshwater usage.

Suitability

This technology is suitable for use in areas suited for irrigated agriculture, and is especially suitable for use on large farms.

Advantages

Use of this technology results in significant water savings and improved environmental protection.

Disadvantages

Irrigation equipment requires an high degree of maintenance. Parts for older-style irrigation systems may not be readily available, and it may be necessary to replace older equipment with more modern (and readily available) machinery.

Cultural Acceptability

This technology is related to traditional methods of fodder production and is well-accepted.

Further Development of the Technology

A better understanding of the economic value of the environmental protection benefits is needed. Also, monitoring should be conducted to determine the long term environmental issues relating to using this type of technology.

Information Sources

Rolands Bebris, Ministry of Environmental Protection and Regional Development, 25 Peldu Str., 1494 Riga, Latvia, Tel. (371-7) 227145, fax: (371-7) 820442, e-mail: BEBRI@VARAM.GOV.LV.

Anna Egle, V/U "Meliorprojects", 11 Novembra Bulvaris 31, LV-1494 Riga, Latvia, Tel. (371-7) 228734.

Table of Contents

• Brochure
• 
• 



• International Year of Forests
• 
• 



• World Environment Day
• 
• 



• UNEP Campaign
• 
•