For how long does the quality and quantity of residues in the soil affect the carbon compartments and CO2-C emissions?

Abstract

Purpose The mineralization/immobilization of nutrients from the crop residues is correlated with the quality of the plant material and carbon compartments in the recalcitrant and labile soil fractions. The objective of this study was to correlate the quality and quantity of crop residues incubated in the soil with carbon compartments and CO 2 -C emission, using multivariate analysis. Materials and methods The experiment was conducted in factorial 4 + 2 + 5 with three replicates, referring to three types of residues (control, sugarcane, Brachiaria, and soybean), and two contributions of the crop residues in constant rate, CR (10 Mg ha −1 residue), and agronomic rate, AR (20, 8, and 5 Mg ha −1 residue, respectively, for sugarcane, soybean, and Brachiaria), evaluated five times (1, 3, 6, 12, and 48 days after incubation). At each time, we determined the CO 2 -C emission, nitrogen and organic carbon in the soil, and the residues. In addition, the microbial biomass and water-soluble, labile, and humic substance carbons fractionated into fulvic acids, humic acids and humin were quantified.Results and discussion Higher CO 2 -C emissions occurred in the soil with added residue ranging from 0.5 to 1.1 g CO 2 -C m −2 h −1 in the first 6 days of incubation, and there was a positive correlation with the less labile organic soil fractions as well as residue type. In the final period, after 12 days of soil incubation, there was a higher relation of CO 2 -C emission with carbon humin. The sugarcane and soybean residue (20 Mg ha −1 ) promoted higher CO 2 -C emission and the reduction of carbon residue. The addition of residue contributed to an 82.32 % increase in the emission of CO 2 -C, being more significant in the residue with higher nitrogen availability. Conclusions This study shows that the quality and quantity of residue added to soil affects the carbon sequestration and CO 2 -C emission. In the first 6 days of incubation, there was a higher CO 2 -C emission ratio which correlates with the less stable soil carbon compartments as well as residue. In the final period of incubation, there is no effect of quality and quantity of residue added to soil on the CO 2 -C emission.

Biochar insights from laboratory incubations monitoring O2 consumption and CO2 production

“…Soil CO 2 emission directly results from plant roots and microorganism respiration by biochemical processes (Melillo et al 2002;Davidson and Janssens 2006), consuming oxygen (O 2 ) and producing CO 2 emissions through organic matter decomposition (Chen et al 2011). Soil temperature, moisture, microbial abundance, and substrate quality and availability are major properties that control soil CO 2 emission (Almeida et al 2015). The net CO 2 emission from the soil is also controlled by overall soil use and tillage management decisions that also directly influence the processes of CO 2 sequestration and emission (i.e., Figueroa et al 2008;Huang et al 2012;ESRL 2016).…”

Decadal Nitrogen Fertilization Decreases Mineral‐Associated and Subsoil Carbon: A 32‐Year Study

“…roots), which decomposes slowly (Cotrufo et al, ). However, in contrast to low quality, accelerated decomposition of high‐quality residues (e.g., under high N availability) can promote C losses (as CO 2 emissions or leaching of dissolved C) more than stabilization within SOM (De Almeida et al, ; Pabst et al, ). The soil N availability and residue decomposability (with contrasting quality) can, therefore, affect the partitioning of C within SOM fractions and its distribution along soil depths.…”

Recalcitrant carbon and nitrogen in agriculture soils with residue accumulation and fertilization under tropical conditions

“…TOC presented a variation between 1.2 to 3.3 %, decreasing at soil depth with higher difference at FC (± 0.8 %), following CC (± 0.7 %), Figure 1. TOC decrease with soil depth has been reported in various articles (COLLETO et al, 2015;ALMEIDA et al, 2014;SANTANA et al, 2011;PULROLNIK et al, 2009), with highest TOC in surface due to accumulation and decomposition of vegetal and animal materials (ROSCOE et al, 2006), which depending on quality and quantity of the residues to increase TOC in soil (ALMEIDA et al, 2016).…”

“…The highest concentration of TOC and TON in FL and FC, was expected and is due to greater stability and less human intervention, which results in constant maintenance of plant residues and microorganisms responsible for mineralization. Generally, TON content is fall rapidly in soil cultivated with cereals, legumes and pasture due to N needs of microorganism (ALMEIDA et al, 2016;STEVENSON 1994).…”