Farm Irrigation Efficiency

Project Drawdown defines Farm Irrigation Efficiency as: a set of energy-efficient irrigation practices that increase crop yields while reducing emissions. This solution replaces conventional irrigation on irrigated cropland.

Pumping and transporting water accounts for 70-80 percent of global water use, and is a major use of energy. Much of this irrigation is delivered using inefficient methods such as flood irrigation. Employing improved Farm Irrigation Efficiency practices across the agricultural system can bring about water and greenhouse gas savings as high as 25 percent and 40 percent under sprinkler and drip methods, respectively, compared with conventional irrigation methods.

Of course, irrigation is critical to crop production, particularly in the era of climate change with increasingly unpredictable rains. For this reason, efficient irrigation is highly rated as a climate change adaptation strategy.

Methodology

Total Land Area[1]

The total land area for this solution is irrigated cropland, totaling 320 million hectares.[2] Current adoption[3] of efficient Farm Irrigation Efficiency is 53.8 million hectares, The adoption of drip and sprinkler irrigation system is taken from the ICID, FAO Aquastat and National Statistics. Current adoption value for the year 2018 is interpolated based on the average value estimation for the years, 1999, 2009, and 2017. ).

Adoption Scenarios[4]

Seven custom adoption scenarios were developed based on the aggregated region-level data. Some of the custom adoption scenarios assume higher growth rates for all regions except the OECD, which has a much higher current adoption than other regions. Considering global water scarcity, some scenarios assumes an early peak adoption by 2030.

Impacts of increased adoption of Farm Irrigation Efficiency from 2020-2050 were generated based on two growth scenarios, which were assessed in comparison to a Reference Scenario where the solution’s market share was fixed at the current levels.

• Scenario 1: Analysis of these seven custom scenarios results in the adoption of 187.7 million hectares for Farm Irrigation Efficiency under this scenario.
• Scenario 2: This scenario results results in the adoption  of 286.5 million hectares.

Emissions Model

Climate impacts of Farm Irrigation Efficiency are based on the difference between the electricity required per hectare for conventional and improved irrigation systems. Meta-analysis of Food and Agriculture Organization (FAO) data found that conventional irrigation requires 2.3 terawatt-hours per million hectares per year, while improved irrigation uses 1.5 terawatt-hours per million hectares per year.

Financial Model

Conventional first cost for irrigation is US$671.37 per hectare,[5] based on 13 data points from 10 sources. First cost for the Farm Irrigation Efficiency solution is US$1,575.86 per hectare, based on meta-analysis of 37 data points from 22 sources. Conventional operational cost is US$274.04 per hectare. Operational cost per hectare for Farm Irrigation Efficiency is US$151.02,. ,  The operational cost for both conventional practice and for the solution is estimated by using the percentage of  the total water withdrawal and the total cost of withdrawal in respective case.

Integration[6]

Unlike most Drawdown solutions, the Farm Irrigation Efficiency solution can be applied to units of land where other solutions are taking place, as it was determined that the emissions reduction from improved irrigation is independent from, for example, biosequestration from conservation agriculture or tree intercropping.

Results

Total adoption of Farm Irrigation Efficiency in the Scenario 1 is 187.7million hectares in 2050, representing 59 percent of the total available land. Of this, 133.95 million hectares are adopted from 2020-2050. The emissions impact of this scenario is 1.13 gigatons of carbon dioxide-equivalent reduced by 2050. Net cost is US$222.9 billion. Net savings in operational cost is US$534.6 billion. This solution also saves 37 billion gallons of water.

Total adoption in the Scenario 2 is 286.5 million hectares in 2050, representing 89 percent of the total available land. Of this, 232.72 million hectares are adopted from 2020-2050. The impact of this scenario is 2.07 gigatons of carbon dioxide-equivalent reduced by 2050. Net cost is US$386.9 billion. Net savings in operational cost is US$938.6 billion. This solution also saves 68 billion gallons of water.

Discussion

Benchmarks

Few benchmarks are available to provide comparisons for this study. The FAO noted in 2011 that no published figures were available on greenhouse gas emissions from irrigation (Turral et al., 2011).

Limitations

Additional data points on the emissions and irrigation costs of Farm Irrigation Efficiency would improve this study. It would also be worthwhile to model extending improved irrigation to currently rainfed areas to increase yields as a form of agricultural intensification.

Conclusions

Irrigation efficiency is a win-win solution. It increases food security in a world with increasingly unpredictable weather, reduces water use, and reduces emissions.