Irrigation

By Evan, Zoe, Jonah, and Caleb

Introduction

Irrigation is defined as the artificial application of water to land, either for agricultural production or for nonagricultural purposes as well. It is a way to supplement rainfall and increase the productivity of the land. Irrigation is usually done through systems of underground pipes, pumps, and sprinklers that disperse water. Irrigation water can come from surface reservoirs, such as ponds, rivers, or lakes, but it can also come from below the surface. Wells are typically used to tap into the subsurface water. Other sources of irrigation water can be dew or wastewater, although these are less common (Jones, 2023). Irrigation is currently responsible for about 70% of all freshwater withdrawals worldwide, and the majority of this water is eventually returned to the aquifer it is drawn from. However, there are potential environmental hazards with irrigation, especially if water is drawn faster than it is replenished (Kelly, 2020).

https://www.fao.org/aquastat/en/geospatial-information/global-maps-irrigated-areas/latest-version/

Global Perspective

The Food and Agriculture Organization (FAO) estimates that around 680 million acres of land are irrigated worldwide. Asia accounts for nearly 70% of this irrigated land, mostly through China, India, and Pakistan (Jones, 2023). Also, as demonstrated by the map to the left, the United States and many countries in Europe heavily contribute to the amount of irrigated land. This statistic is likely to continue increasing in the future, perhaps to as much as 4.4 billion acres of irrigated land. Many people see the benefits of irrigation because it makes land more fertile for agriculture and allows for increased productivity in food. However, there are problems arising from irrigation. The main issue is that our water supply is limited, and more irrigation means we may need to find new sources of water to ensure that there is a large enough supply to sustain us and our growing population (Kelly, 2020).

USDA ERS - Irrigation & Water Use

National Perspective

In 2015, irrigation accounted for 42% of the United States’ total freshwater withdrawals. In total, the US is responsible for 58 million acres of irrigated land. Some states rely more heavily on irrigation than others, as shown in the map to the left. Nebraska had the most irrigated land in the US, followed by California and Arkansas. California is a good example of where irrigation could have some negative consequences in the future. Access to clean drinking water in California has been an issue recently, especially with droughts and freshwater reservoirs being depleted quickly. Sustainable irrigation practices will need to be implemented in order to avoid water shortages (Hrozencik, 2022).

mlive.com

Local Perspective

Ottawa County has been dealing with water shortages since 2008, when they were first reported by residents. This is because around 11,000 industrial and agricultural wells were tapping into the groundwater. Ottawa county has only a few aquifers to draw from, and with limited rainfall here, these aquifers aren’t replenishing fast enough. Allendale now requires new houses to connect to city water instead. With water levels down around 40 feet in the last 50 years, a new strategy for irrigation will need to be implemented if we want to maintain local aquifers (Center, 2019).

Background Research

A preliminary study was done in 2013 assessing the problem of unreliable groundwater availability and elevated salinity. What they found is that there has been a modest to significant decline in static water levels especially for the bedrock aquifer. The Phase 1 study also showed an increase in chlorine levels (above recommended levels) in municipal wells sampled over the last 30 years. To understand what the exact causes are and to address the problem head-on Phase 2 was created compiling scientific data and precise modeling in 2018.

High concentration of chloride can cause problems for crops especially in the lower peninsula such as blueberries, potatoes, and corn (Ayers, 1985). Possible anthropogenic sources include roadway deicers (road salt), septic tank effluent, agricultural fertilizers (e.g., potassium chloride) and leaky oil/gas wells. (Phase II, 2018). Since Ottawa County is the fastest growing county in Michigan, excessive groundwater pumping has created “artificially” low groundwater levels. In the figure below it shows the distribution of groundwater use between domestic wells, public supply, irrigation, and industry. As you can see, irrigation has a significant impact on the amount of groundwater supply and has led to decreasing static water levels as well as elevated chlorine levels.

Drip Irrigation

One of the solutions that could be implemented at the SAP is drip irrigation. It is considered the most efficient water and nutrient delivery system for growing crops. This alternative irrigation system delivers water and nutrients directly to the plants' root zone, in the right amounts, at the right time, so each plant gets exactly what it needs, when it needs, for optimal growing. How does it work you might ask? Water and nutrients are delivered directly to each plant in pipes known as 'driplines', featuring small units called 'drippers' (Netafim) This system allows for consistent water and nutrient application to the whole crop. Since the SAP is a small-scale sustainable operation this irrigation system would make the most sense and would decrease the amount of stress on Ottawa County's depleting aquifer.

Implementation plan

Drip irrigation can deliver significant increases in yield (bringing more money into the SAP) as well as saving costs for water and fertilizer. The installment of drip irrigation is not very complex, rather, most of the significant work to be done is establishing which type of soil one has and the layout of the drip lines. If the soil has a high permeability which means it is primarily sand, then the drip holes should be spaced closer together at about 150 mm apart. If the soil is low in permeability meaning it is much like clay, then the drip holes should be spaced further away at about 500mm. The best way to establish the layout of the lines is by looking at a scale of the garden, one in which provides a certain amount of square meterage which will allow one to decipher how much line is needed. But also because the scale will provide a visualization of a grid in the crops and how the drip lines should be snaked through to maximize efficiency. Once these measurements are established, the only thing left to do is to purchase the required materials. These include: Back flow Prevention Kit, Tap timer (optional), Arkal Disc Filter, Pressure Reducing Valve (PRV), Air Release Valve, Low Density Poly Pipe, Drip line, Wire Pegs, Adaptors and fittings, and lastly a Line Automatic Flushing Valve. (SEO, 2021) A simplistic diagram of the drip system is provided here:

Timeline

Budget

As we were unable to find the exact square footage that the SAP is now utilizing for crops, we are unable to give an exact budget. With this said, drip irrigation overall is relatively cheap to implement in the long run. The installment of this system will typically run around $1.60 - $4.00 per square foot. (How, 2023). Seeing that the SAP sits on 1.36 acres, and assuming that 80% is used for agriculture, installing this system could cost the SAP $76,096 - $190,240. Now, this can vary depending on how in depth one wants to go. For example, if one wanted to implement a solar panel, allowing the process to be completely self-sufficient, the cost would go up to about $80,096 and $194,240 respectively. but could be very beneficial in the long run.

References

SEO, Admin. “How to: Install Your Own Drip Irrigation System.” Dural Irrigation, Dural Irrigation, 27 May 2021, https://duralirrigation.com.au/blogs/irrigation-diy/installing-a-drip-irrigation-system.

Jones, B. (n.d.). Irrigation | definition, history, systems, & facts | britannica. Retrieved March 17, 2023, from https://www.britannica.com/technology/irrigation

Kelly, M. (n.d.). Expansion, environmental impacts of irrigation by 2050 greatly underestimated. Princeton University. Retrieved March 17, 2023, from https://www.princeton.edu/news/2020/05/05/expansion-environmental-impacts-irrigation-2050-greatly-underestimated

Hrozencik. (n.d.). Irrigation & Water Use. USDA ERS - Irrigation & Water Use. Retrieved March 17, 2023, from https://www.ers.usda.gov/topics/farm-practices-management/irrigation-water-use/

Center, P. (2020, January 13). Ottawa County's ground water crisis. WGVU NEWS. Retrieved March 17, 2023, from https://www.wgvunews.org/midday-west-michigan/2019-12-26/ottawa-countys-ground-water-crisis

“How Much Does Drip Irrigation Cost in 2023? - Lawn Care Blog: Lawn Love.” Lawn Care Blog | Lawn Love, 24 Jan. 2023, https://lawnlove.com/blog/drip-irrigation-cost/#:~:text=in%20Your%20Area-,The%20average%20cost%20of%20a%20residential%20drip%20irrigation%20system%20is,about%20%242.80%20per%20square%20foot.

“How Much Does a Solar Water Pump Cost?” RPS Solar Pumps | America's #1 Solar Well Pumps, https://www.rpssolarpumps.com/solar-pump-faq/how-much-does-a-solar-water-pump-cost/.