Circular Buffer Strips of Native Perennial Grasses to Sustain Ogallala Aquifer

In the semi-arid US Great Plains, declining Ogallala aquifer needs new ideas to ensure the sustainability of the aquifer and resiliency of irrigated agriculture. The region also faces multiple challenges including extreme wind and water erosion, increasing climate extremes, decreasing soil health and declining biodiversity. Increasing number of partial pivots created by reduced well outputs, where only part of the pivot is irrigated, created an opportunity to develop a new concept Circular Buffer Strip (CBS). It is a simple and cost-effective strategy of rearranging the dryland portion of a partial pivot into circles of buffer strips of native perennial grasses alternating with crop strips to enhance multiple ecosystem services including improving efficiency of water cycle. Aerodynamic principles, grass height and farm equipment sizes are used in deciding the width of grass and crop strips. It conservs intense and offseason rainfall, improves crop microclimate to mitigate plant stresses, and improves water use efficiency of the system. A landscape study was initiated at Agricultural Research Center at Clovis in 2016. A mixture of seven tall growing cool and warm season grasses were planted in the circular buffer strips and grain corn was planted in strips alternating with grass strips and in the control pivot. The objective of this is to assess temporal and spatial distribution of benefits from single and multiple buffers. Improved precipitation conservation, crop productivity and water use efficiency are consistently observed in this long term study. Wind moderation, which reduces evaporation was consistently observed. Observations of moisture conserved after large rainfall events ( 50mm) during the last two years clearly indicated that crop strips of CBS stored 18 to 25% more water compared to corn strips in control pivot without buffers. This improved water extraction from the soil profile, reduced water stress and improved biomass production in CBS corn after 4-7 days. In addition, wind moderation effect by grass strips conserved 3 and 26% higher moisture at 5 cm depth in 2019 and 2020, respectively. Improved water conservation and efficient use improved combine harvested corn yield by 10 to 15% and depending on the season the benefits extended to 72 m from out edge of the center pivot. As a result, corn water use efficiency in CBS was 18% higher than CT over two years. Thus, wide scale adoption of the concept in the southern Great Plains can reduce water pumped from the aquifer by reducing irrigated acreage and by improving water productivity. Improvements of other ecosystem services and climate resiliency will be additional attractions to adopt the concept.