Carbon dioxide emissions as affected by alternative long-term irrigation and tillage management practices in the lower Mississippi River Valley.

S Aaron Smith ,Kristofor R Brye

doi:10.1155/2014/626732

S Aaron Smith , Kristofor R Brye

Open Access

https://doi.org/10.1155/2014/626732

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Abstract

Ensuring the sustainability of cultivated soils is an ever-increasing priority for producers in the Lower Mississippi River Valley (LMRV). As groundwater sources become depleted and environmental regulations become more strict, producers will look to alternative management practices that will ensure the sustainability and cost-effectiveness of their production systems. This study was conducted to assess the long-term (>7 years) effects of irrigation (i.e., irrigated and dryland production) and tillage (conventional and no-tillage) on estimated carbon dioxide (CO2) emissions from soil respiration during two soybean (Glycine max L.) growing seasons from a wheat- (Triticum aestivum L.-) soybean, double-cropped production system in the LMRV region of eastern Arkansas. Soil surface CO2 fluxes were measured approximately every two weeks during two soybean growing seasons. Estimated season-long CO2 emissions were unaffected by irrigation in 2011 (P > 0.05); however, during the unusually dry 2012 growing season, season-long CO2 emissions were 87.6% greater (P = 0.044) under irrigated (21.9 Mg CO2 ha−1) than under dryland management (11.7 Mg CO2 ha−1). Contrary to what was expected, there was no interactive effect of irrigation and tillage on estimated season-long CO2 emissions. Understanding how long-term agricultural management practices affect soil respiration can help improve policies for soil and environmental sustainability.

Highlights

Soybean (Glycine max L.) is a major crop grown in the Lower Mississippi River Valley (LMRV)
20% of soybean produced in eastern Arkansas was grown in a dryland cropping system [7]
The 30-year monthly rainfall in eastern Arkansas ranges from 6.9 cm in August to 11.1 cm in June and totals 45.3 cm throughout the 5-month soybean growing season [18]

Summary

Introduction

Soybean (Glycine max L.) is a major crop grown in the Lower Mississippi River Valley (LMRV). Arkansas produces the greatest amount of soybean of the three states that generally constitute the LMRV (i.e., Arkansas, Louisiana, and Mississippi) and is ranked eighth nationally for total economic gain from soybean production [1]. The Alluvial Aquifer, which is the southeastern portion of the Mississippi embayment, is the major source of groundwater used for irrigation in this dense, agriculturally productive region. The Alluvial Aquifer is ranked third in the nation for total annual withdrawals [2], and most of the water is used for irrigated crop production, rice (Oryza sativa L.) and soybean [3]. Increased withdrawal rates from the Alluvial Aquifer, due in part to increasing areas of irrigated rice and soybean production and shifting rainfall patterns during the growing season, have led to substantial decreases in groundwater levels throughout eastern Arkansas and the neighboring states [4]. The lack of available water in a dryland cropping system can result in yield loss

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