Carbon Sequestration and Dynamics of Two Irrigated Agricultural Soils in California

Abstract

Irrigation in semiarid regions can alter soil C sequestration processes compared with those of native soils. To better understand the effect of these altered processes, we studied the C sequestration and dynamics of two soils from major irrigated agricultural regions of California (the San Joaquin Valley and the Imperial Valley). Soils were sampled from selected native and cultivated fields to represent a span of almost a century of irrigated farming. Field soil samples were analyzed for total soil C and soil inorganic C as carbonate (SIC). Soil organic C (SOC) was then calculated from the measured data. Results showed that SOC stock increased above that stored in the native soil after five decades of irrigated farming. The SIC stock showed opposing trends within the top meter of the two studied soils: a decrease was measured after 55 yr in the San Joaquin Valley soil, while SIC in the Imperial Valley soil increased after 85 yr of irrigated agriculture and appears to represent a significant form of sequestered soil C. Our results indicate that long‐term irrigated farming can significantly increase SOC due primarily to SOC added below the 10‐cm soil depth, while significant increases in SIC may be partially due to the conversion of increased soil CO2 to carbonates under a regime of Colorado River irrigation water. Thus, when considering C sequestration in irrigated agriculture in semiarid regions, it is important to determine levels of both SOC and SIC.

Sequestration of Organic Carbon Influenced by the Application of Straw Residue and Farmyard Manure in Two Different Soils

“…The higher the rate of added organic matter was, the higher increase in SOC content was observed. This result is consistent with the findings of Wu et al (2008), who found an increase in the final SOC content after application of organic matter. Similarly, Adesodun and Odejimi (2010) observed that carbon sequestration was enhanced with the application of pig-composted manure.…”

“…In fact, CO 2 produced due to carbon mineralization could be emitted more easily and faster from the uncultivated soil than from the cropland soil, which had a heavier texture and higher ability to protect SOC against microbial decomposition. This result is consistent with the finding of Wu et al (2008), who reported that soil texture is a core determinant of SOC. They concluded that fine-textured 174 M. MAHMOODABADI and E. HEYDARPOUR Fig.…”

“…Storage of SOC in agricultural systems is a balance between carbon additions from non-harvested portions of crops (Wu et al, 2008), organic sources (Thelen et al, 2010), and carbon losses, primarily through organic matter decomposition and release of respired CO 2 to the atmosphere (Bird et al, 2002). For centuries, organic matter has been applied to agricultural soils as a means of supplying the crops with nutrients and maintaining the required SOC content with benefits to soil structure (Balashov et al, 2010).…”

A Review of the Role of Vegetal Ecosystems in CO2 Capture

“…The realization of this objective requires creating, sharing, and applying new multi-level knowledge, and several actions, such as testing new crops and cultivars, the introduction of new technologic processes linked to major water use efficiency (adopting drip and sub-irrigation), the adoption of agricultural practices that are less carbon intensive, and the enhancement of agronomic productivity per unit consumption of C-based, must be taken. Finally, the management of agricultural practices should be addressed to optimize the use of soil, as a whole, and to reduce energy and resource consumption, taking into account different agricultural ecosystems from a holistic and multidisciplinary approach, thus reinforcing the role of endogenous resources in combination with public initiatives [18,[50][51][52][53][54][55][56].…”

Evaluation of soil carbon stocks in response to management changes in sugarcane production

“…This could impact microbial activities, and if the model is predicting higher of irrigation that is occurring this would possibly result in lower soil C stocks accumulation rates than predicted. Wu et al (2008) also studied a long-term irrigation practice under cultivated fields and stated that fast accumulation in soil C stocks occurred in at 10-25 cm as result of incorporation organic matter during tillage and through inputs from crop roots. Tillage in our long-term predictions, was simulated every 7 years, this was linked to a modelled increase in soil C stock.…”