Soil Respiration as Affected by Long-Term Broiler Litter Application to a Udult in the Ozark Highlands

Abstract

The United States produced 8.4 billion broiler chickens () and an estimated 10.1 to 14.3 million Mg of broiler litter (BL) in 2012. Arkansas' production of 1 billion broilers in 2012 produced an estimated 1.2 to 1.7 million Mg of BL, most of which was concentrated in the Ozark Highlands region of northwest Arkansas. Increased CO release from soils associated with agricultural practices has generated concerns regarding the contribution of certain agricultural management practices to global warming. The objectives of this study were to evaluate the effects of long-term (>6 yr) BL application to a Udult on soil respiration and annual C emissions and to determine the predictability of soil respiration based on soil temperature and moisture in the Ozark Highlands region of northwest Arkansas. Soil respiration was measured routinely between May 2009 and May 2012 in response to annual BL application rates of 0, 5.6, and 11.2 Mg dry litter ha that began in 2003. Soil respiration varied ( < 0.01) with BL rate, measurement date, and year. Additions of BL stimulated respiration after application, and rainfall events after dry-soil conditions stimulated respiration in all years. Soil temperature at the 10-cm depth, 0- to 6-cm soil volumetric water content (VWC), and annual CO-C emissions were unaffected ( > 0.05) by BL application rate but differed ( < 0.01) among study years. Multiple regression indicated that soil respiration could be reasonably predicted using 2-cm-depth soil temperature (T) and the product of T and VWC as predictors ( = 0.52; < 0.01). Results indicate that organic amendments, such as BL, can stimulate release of CO from the soil to the atmosphere, potentially negatively affecting atmospheric greenhouse gas concentrations; thus, there may be application rates above which the benefits of organic amendments may be diminished by adverse environmental effects. Improved BL management strategies are needed to lessen the loss of CO from BL-amended soils.

Seasonal Effects on Leachate Quality from an Ozark Highlands Managed Grassland Using Automated, Equilibrium‐Tension Lysimeters

“…Reporting on the results of the first 2 yr of BL application in this same long-term study, Pirani et al (2006) demonstrated that leachate-As concentrations differed among BL rates in at least one 3-mo season and that As and Se leachate loads were at least numerically elevated in response to the increasing BL application rate. Similar results were also reported by McMullen et al (2015) for the annual summary of the 8-yr data set. However, soil leachate solution would probably undergo many reactions and attenuations, even in areas of karst geology, before it was able to mix with nearby or regional surface waters.…”

“…Seasonal leachate DOC load averaged 3.9 kg ha −1 across BL rates with time (Table 2). Despite a large C concentration in the applied BL, DOC leaching was relatively low from the litter treatments because the C additions from the applied BL stimulated increased soil respiration (McMullen et al, 2015). Seasonal leachate loads of all other elements and compounds measured in this study averaged <0.3 kg ha −1 across BL rates with time (Table 2).…”

Soil CO2 evolution is driven by forage species, soil moisture, grazing pressure, poultry litter fertilization, and seasonality in silvopastures

“…Soil moisture and temperature are the most common abiotic variables affecting soil respiration (Chen et al, 2008;Hibbard et al, 2005). Previous studies have reported positive (Brown et al, 2009), negative (Ding et al, 2010;Jones et al, 2006;McMullen et al, 2015;Singh et al, 2019), and no correlation (Al-Kaisi & Yin, 2005) between CO 2 flux and soil moisture. Moisture provides access to microbial substrates (Chen et al, 2008;Harper et al, 2005;Hibbard et al, 2005), and plant root respiration may increase with water and N availability (Valentini et al, 2000).…”

“…Moisture provides access to microbial substrates (Chen et al., 2008; Harper et al., 2005; Hibbard et al., 2005), and plant root respiration may increase with water and N availability (Valentini et al., 2000). Soil temperature accounts for a large portion of seasonal and daily CO 2 variation (Davidson et al., 1998) and has been correlated with soil CO 2 flux in a range of environmental settings (Ding et al., 2010; Epron et al., 1999; Fang & Moncrieff, 2001; Hibbard et al., 2005; McMullen et al., 2015; Ruehr et al., 2010). As agricultural soils are important contributors to the global C cycle and C storage amounts are subject to management practices (Roberson et al., 2008), other environmental factors that affect soil respiration warrant further investigation (Hibbard et al., 2005).…”