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eNews May 2021

NMSU Student Studies Water Conservation with Circular Grass Buffer Strips

NMSU Student Studies Water Conservation with Circular Grass Buffer Strips

By Marcus Gay, NM WRRI Student Program Coordinator

Water security is a monumental challenge for semi-arid regions around the country, including eastern New Mexico. The Ogallala Aquifer’s dwindling groundwater reserves threaten the area’s agricultural production, economy, and rural livelihoods. The transition from irrigated farmland to dryland farming in this area has already started in the form of partial pivot circles, where only a portion of the pivot (generally 2/3) is under full irrigation and the rest is kept dry. Semi-arid conditions and low rainfall severely impacts this kind of dryland production. Increasing irrigation water use efficiency and improving the use of rainwater on crop fields would allow farmers to reduce irrigation without significantly affecting crop yield, and as a result would help sustain the aquifer. Research has shown that this region is receiving an increasing amount of its rainfall in large rainfall events. The current annual cropping system is unable to effectively capture rainwater from these high intensity, short duration precipitation events. A major portion of the rainwater from these storms is lost as surface runoff, which also washes away topsoil and nutrients. An innovative strategy that conserves more of this rainwater is needed to increase water efficiency.

NM WRRI has awarded New Mexico State University PhD student Paramveer Singh a Student Water Research Grant to work on a project that offers several benefits, including improving the efficiency of rainwater. Under the guidance of his faculty advisor, Dr. Sangu Angadi, Singh is working on a simple and cost-effective strategy that rearranges the dryland portion of partial pivots to improve multiple ecosystem services. The project is entitled, Improving Green Water Use Proportion in a Center Pivot Irrigation System by Using Circular Grass Buffer Strips, and studies the novel concept of rearranging the dryland portion of partial pivots into circular buffer strips of native perennial grasses growing 3-4 ft tall and alternating with irrigated crop strips.

The system provides multiple barriers to surface runoff and wind flow. The research team expects the system to reduce runoff, increase infiltration of rainwater, and reduce evaporation loss. To explore and gauge the potential benefits of wind moderation by circular grass buffer strips, a multi-year study has started at NMSU’s Agricultural Science Center in Clovis, New Mexico. Five circular buffer strips of perennial grasses were planted in June 2016 in the southwest quarter of a center pivot at the station. The southwest quarter of another nearby center pivot serves as a control. The grass buffer strips were arranged alternately with crop strips. In the past three years, the research evaluated micro-climate, corn physiological response, and grain yield response. Encouraging soil moisture results after rainfall events inspired the research team to carry out an in-depth assessment of the proportion of rainwater use under the two systems. For this part of the project, Dr. Robert J. Lascano, from the United States Department of Agriculture Agricultural Research Service (USDA-ARS) in Lubbock, Texas, will collaborate with the team. Initial soil and plant samples will be collected before rainfall events during the corn growth period (June to September). Rainwater for each event will be collected and analyzed to determine its isotopic composition. After a rain event, plant samples will be taken every two hours during daylight for four days. Soil samples will be taken every eight hours. The amount of rainfall received will determine the depth of soil samples. Sealed and frozen samples will be examined at USDA-ARS in Lubbock, Texas, for isotope signature.

Preliminary results are indicating a 46% improvement in water conserved after a heavy rainfall event. As Singh explains, “We expect a significant increase in rainwater (green water) use by corn with circular buffer strips as conservation of heavy rainfall events improve significantly. More of that water will be used in the production process for a period of time after each rainfall event. If that contribution is significant, irrigation management can be altered to reduce Ogallala Aquifer water use and improve water use efficiency.” According to Singh, precipitation is going to play a vital role in the region’s agricultural production system as aquifer depletion continues. This novel system may prove to be a much-needed solution for both irrigated and dryland production systems and the rural economy of the entire region.

Singh has presented this research at the 2020 Crop Science Society of America – Soil Science Society of America International Annual Meeting and the 65th Annual New Mexico Water Conference. Originally from the village of Kheri Jattan of Punjab, India, Singh plans to finish his PhD in Agronomy and Crop Science in 2022. After graduation, Singh would like to continue working in the field of agricultural research because, as he explains, “my home state Punjab is facing a similar water crisis issue where over-pumping of groundwater for rice production has severely declined the water table. I would love to use my experience and knowledge garnered here at NMSU to contribute to solving water scarcity problems back home in whatever capacity.”