Every Row and Skip Row Irrigation Impacts on Soybean Production in the Mississippi Delta

Investigators: Hayden Burford, Gurbir Singh, Bhupinder Singh, Dillon Russell, Trey Freeland

Funding Agency: USDA-NASS

Date: 2021

Project Summary

Introduction

Mississippi soybean production in 2020 was more than two million acres. Around 80% of soybeans produced in Mississippi were in the Mississippi Delta Region. Within the Delta, 75% of the soybeans produced were irrigated (USDA- NASS, 2020). The Mississippi River Valley Alluvial Aquifer (MRVAA) is used to supply more than 90% of irrigation water to the Delta region (Dyer et al., 2015). Due to the excessive pumping of groundwater for irrigation, MRVAA water levels have been declining steadily. Different irrigation practices are needed to help slow and eventually stop the decline in the aquifer before the water level gets to an alarming level. Irrigating soybeans on a skip row irrigation plan instead of every row irrigation plan is one way to help lower the groundwater pumping amounts and thereby conserve the aquifer water. Therefore, the objective of this study was to evaluate soybean yield response to every row (ER) irrigation and skip row (SR) irrigation with different irrigation initiation sensor thresholds.

Materials and Methods

This experiment was conducted at the National Center for Alluvial Aquifer Research (NCAAR), Stoneville, MS (33°25′26″N, 90°54′54″W) in the 2020 and 2021 growing seasons. This study was done on a Bosket very fine sandy loam soil series. Treatments were established in a randomized complete block design. The treatments in this experiment were a combination of irrigation row spacing (every row and skip row) and irrigation scheduling sensor thresholds at three different centibars (cb) readings (-40 cb, -70 cb, and -100 cb) with a dryland control. For the 2020 growing season, Bayer Crop Science Asgrow 46X6 was planted at 130,000 seeds/ac on 40-inch beds. For the 2021 growing season, Bayer Crop Science Asgrow 46X0 was planted at 130,000 seeds/ac on 40-inch beds. Soybean was planted on 5/5/2020 and 4/22/2021 with a 4-row John Deere Max-Emerge single-row planter. Fertilizer was applied on 4/7/2021 in the form of triple superphosphate (TSP) and muriate of potash (MOP) at a rate of 0-50-100 lb/ac. Watermark soil moisture sensors were installed at depths of 6, 12, and 24 inches and wired to a Trellis data logger (Peachtree Corners, Georgia) for soil water potential data collection. Soybean was harvested with a Kincaid 8xp plot combine (Haven, Kansas) equipped with a harvest master H2 grain gauge.

Results and Discussion

The SR -70 cb treatment had at least 8% higher yield than the SR -40 cb, SR -100 cb, and dryland treatments in 2020. The ER- 40 cb, ER -70 cb, and ER -100 cb were statistically the same as but numerically higher than the SR- 40 cb, SR -100 cb, and dryland treatments. In 2021, no statistical differences were observed for soybean yield. However, the most conservative treatment (SR -100 cb) had statistically the same yield as the most conventional treatment (ER -40 cb) while receiving less irrigation.

Conclusion

Results from both years of this study show that soybean yields can be maintained with skip row irrigation. This research also showed that yields can be maintained while using a more conservative irrigation plan with the SR -70 cb and the SR -100 cb having statistically comparable yields to the SR 40 cb in the 2021 growing season.

References

Dyer, J., Mercer, A., Rigby, J. R., & Grimes, A. (2015). Identification of recharge zones in the Lower Mississippi River alluvial aquifer using high-resolution precipitation estimates. Journal of Hydrology, 531, 360-369.

USDA-NASS. (2020). 2020 State Agriculture Overview for Mississippi. https://www.nass. usda.gov/Quick_Stats/Ag_Overview/state- Overview.php?state=MISSISSIPPI

Project Photos

• Crop Type:
• Soybean

• Topic:
• Irrigation Scheduling
• Irrigation