Impact of Tillage and Residue Burning on Carbon Dioxide Flux in a Wheat–Soybean Production System

Abstract

Burning of wheat (Triticum aestivum L.) residue followed by plowing is a common management practice in wheat–soybean [Glycine Max (L.) Merrill] production systems in the mid‐southern USA. However, this residue management practice is not environmentally friendly and may not be sustainable. The objectives of this study were to (i) evaluate the effects of N fertilization of wheat, residue burning, and tillage on soil surface carbon dioxide (CO2) flux in a wheat–soybean double‐crop production system, and (ii) evaluate the role of soil temperature and soil moisture in controlling CO2 flux in a relatively warm, subhumid environment. Soil surface CO2 flux was measured nine times between June 2002 and October 2003 during the soybean growing season under all combinations of conventional‐ (CT) and no‐tillage (NT) at high and low N fertilization levels with and without residue burning at two locations in the Mississippi River delta region of eastern Arkansas. Soil surface CO2 flux was 37.6% higher (P < 0.01) from CT than from NT and 6.1% higher (P < 0.05) from the low than the high N rate treatment at one location, but not at the other. Burning did not affect soil surface CO2 flux except for a significant burning × N rate (P = 0.016) and burning × time interaction (P = 0.032) at one location, but not at the other. Both soil temperature and moisture parameters were significantly negatively correlated with temperature‐normalized soil surface CO2 flux, but soil temperature, particularly at the 10‐cm depth, explained more of the variation than did soil moisture parameters. The results of this study indicate that tillage and N fertilization of prior wheat, but not residue burning, affect the loss of C as CO2 from the soil and that there are additional soil and/or environmental factors, other than near‐surface soil moisture and temperature fluctuations, perhaps microbial biomass, that contribute to controlling soil surface CO2 flux in wheat‐soybean production systems in the subhumid region of southern USA.

Daily soil surface CO2 flux during non-flooded periods in flood-irrigated rice rotations

“…Results from this sampling date are different from what was expected based on past studies that reported greater CO 2 flux under conventional tillage than that measured under reduced and no-tillage treatments (Reicosky and Lindstrom 1993;Reicosky et al 1997;West and Marland 2002). These results were also contrary to results in a study evaluating a soybean-wheat rotation on a silt-loam soil in a similar geographic location of east-central Arkansas, which reported a 38 % greater soil surface CO 2 flux under conventional tillage than from that under no-tillage (Brye et al 2006b). However, greater soil surface CO 2 flux under notillage than that under conventional tillage observed in this study on 10 November 2009 was similar to tillage effects on CO 2 emissions in a sorghum (Sorghum bicolor L.)-based cropping system study conducted in Georgia (Hendrix et al 1988).…”

“…Rotations with greater frequencies of corn add significantly more biomass to the soil than rotations with greater frequencies of soybean. Furthermore, the large roots of corn, as opposed to the smaller roots of soybean, create large differences in soil surface CO 2 flux associated with root respiration (Kuzyakov and Cheng 2001;Al-Kaisi and Yin 2005;Brye et al 2006b;Omonode et al 2007). …”

“…Most of the studies that have been performed to investigate the longterm effects of crop rotations on CO 2 emissions have been evaluated in crops such as soybean, corn, and wheat (AlKaisi and Yin 2005;Omonode et al 2007;Brye et al 2006b). However, due to the cyclic anoxic conditions that result from rice production, these dryland crop studies do not pertain to crop rotations that include flood-irrigated rice.…”

Surface organic carbon enrichment to explain greater CO2 emissions from short-term no-tilled soils

“…However, several studies pointed to much lower reduction rates, as for instance 2% by Brye et al (2006) and Sainju et al (2010) in the USA. In contrast, greater CO 2 emissions from NT soils were reported.…”

Gaseous and particulate emission profiles during controlled rice straw burning

“…Despite there have been calls for improvements in harvesting technologies and residue management systems to avoid straw burning (Brye et al, 2006, Gupta et al, 2004, YadvinderSingh et al, 2004, this practice is still common in many areas. Our results provide knowledge on straw conditions, particularly moisture content, affecting pollutant emissions.…”