Irrigating for the Future

New research from the University of California may have uncovered a way to simultaneously  irrigate crops and refill the groundwater table below. The groundwater in California provides its residence with water in times of need. During dry years, groundwater provides 46% of the water supply for Californians. In the last two dry spells, groundwater well levels have dropped some 10 to 50 feet. The state has enacted plans to sustainably manage the groundwater, but at the rate groundwater is being used, who knows how long it will be until there isn’t any left to rely on.

That is why researchers are trying to refill these groundwater reserves. By intentionally flooding fields in the winter months, they hoped to see water percolate deep into the soil and replenish the reserves below. While attempting to do so, they also needed to be aware of the health of the crops in those fields. Researchers noted that over watering the soil could cause disease, damage the roots, and therefore, have a negative economic impact. That is why they decided to perform this experiment with alfalfa. Alfalfa is widely used, nitrogen fixing, and a low economic risk. Since it is nitrogen fixing, it does not require the use of fertilizers and also eliminates the problem of runoff and leaching. Using two well established fields for the experiment, researchers began applying water in 2015 and continued at the second field until 2016.

Once both studies were complete, the data was analyzed and the researchers found that much of the water applied made it deep into the ground. At the first site, 95-98% of the water left the upper root zone of the top 2 feet of soil as deep percolation, traveling 5 feet below into the ground. The second site showed 93-99% of the water entering the ground as deep percolation. There was only one instance where there was a negative relationship between yield and amount of water. This shows that flood irrigating alfalfa fields may be a sustainable possibility to achieve crop yield and manage underground reserves. Although, certain factors may enhance the success of this method. It is recommended that before farmers take up this method, they ensure that their soil is suitable. Soils in this study were very fine, with high porosity. Researchers estimated that 300,000 acres of alfalfa fields in California have soils that would take well to this method.

It would be interesting to see how these results vary from the norm. Groundwater is very important for agriculture and human households, although there isn’t much being done throughout the country to help maintain these reserves. That is why it is so essential that we conserve water when possible, especially if you source your water from a well.

Source: Dahlke, H., Brown, A., Orloff, S., Putnam, D., O’Geen T. (2018) Managed winter flooding of alfalfa recharges groundwater with minimal crop damage. California Agriculture 72(1):65-75.

Photo: Flickr

How to Solve the Water Crisis

Leaky Faucet
Source: Flickr

Water is essential to maintaining all life on earth, yet two billion people worldwide don’t have access to a clean or safe water. However, availability of fresh water may change as seen in an article published on the 9th of February, 2018 in Sciences Advances. This article, titled “Ultrafast selective transport of alkali metal ions in metal organic frameworks with subnanometer pores” details the findings of researchers at both Monash University and the University of Texas at Austin that offers a breakthrough solution to the water crisis.  They discovered that metal-organic frameworks (MOFs), a material with the largest internal surface area of any known substance, can be used to capture and remove salt and metal ions from water.

Metal-organic frameworks are sponge-like crystals that can capture, store, are release chemical compounds. MOFs have a narrow distribution of pore size, making them useful in various separation technologies as well as for the storage of gases like hydrogen and carbon dioxide. MOFs have been used in gas purification and separation, as a catalyst (something that increases the rate of a chemical reaction), or as sensors.

The researchers discovered that MOFs can mimic the filtering function or ‘ion selectivity’ of organic cell membrane. They are able to remove salt from seawater and separate metal ions in a highly efficient and cost effective manner. The researchers estimate that MOFs can improve desalination capacity in water treatment processes by a factor of 2 to 3 in energy consumption. This means there is a more cost-effective, fast way to treat water and make it readily available for those who need it most.

Not only this, but MOFs are able to extract metals that are harmful to humans and otherwise difficult to remove from drinking water. For example, since lithium-ion batteries have become the most popular battery for mobile electronic devices like phones and tablets, they are in such high demand that unconventional methods may have to be developed to continue lithium production, such as extraction from water with metal-organic frameworks.

There are both economic and physical reasons a region could be effected by water scarcity, but the results are the same; humans without the basic necessities of life. It can be caused by lack of investment in technology and infrastructure to collect water from various sources, economic competition for water quantity and quality, or simply the irreversible depletion of drinkable groundwater. The increasing world population, expansion of irrigated agriculture, improving living standards, and changing consumption patterns will only make it more difficult to obtain clean and safe drinking water for all, so these findings published by researchers at Monash University and University of Texas at Austin bring big news to the table in terms of providing the essentials for life to humans worldwide.

Huacheng Zhang, Jue Hou, Yaoxin Hu, Peiyao Wang, Ranwen Ou, Lei Jiang, Jefferson Zhe Liu, Benny D. Freeman, Anita J. Hill and Huanting Wang. Ultrafast selective transport of alkali metal ions in metal organic frameworks with subnanometer poresSciences Advances, 2018; DOI: 10.1126/sciadv.aaq0066