Simulation of management and soil interactions impacting SOC dynamics in sugarcane using the CENTURY Model

Abstract

Newer methods of management and harvesting of sugarcane are being considered to improve soil and water conservation in Brazil. Our aim in this study was to evaluate soil C dynamics under sugarcane cultivation as influenced by the use of conservation management, using measurements from four different management systems and land use histories, i.e. conventional management with preharvest burning, no burning with residue retention and two systems without burning plus additional organic amendments. Field sites also differed in terms of soil texture. We compared field measurements of soil C stocks, 13C and microbial biomass with simulated results from the Century ecosystem model for each of the sites and management histories. We also did long-term simulations of the management treatments and sites to approximate steady-state SOC levels, to explore potential management-induced differences in SOC stocks and interactions with soil texture. The model accurately represented treatment and site differences for total SOC stocks, in which SOC stocks were strongly affected by both rates of organic matter input to soil and soil clay content. However, the model tended to underestimate the relative contribution of sugarcane-derived C to total SOC for sites with high residue and external organic matter amendments. Measured microbial biomass C across the sites was closely aligned with relative amounts of organic matter input but did not appear to be strongly affected by soil texture, whereas the model predicted that both texture and organic matter input rate would impact microbial biomass C. Long-term simulations of the conservation management alternatives suggested that SOC stocks could be maintained at or above levels in the original native Cerradão vegetation, whereas conventional practices using residue burning would result in a reduction of SOC to ca. 60% of native levels. Our results support the use of the CENTURY model as an aid to assess the impacts of different soil management practices on SOC stocks under sugarcane in Brazil.

Sugarcane expansion in Brazilian tropical soils—Effects of land use change on soil chemical attributes

“…Mechanized harvesting associated with reduced tillage and maintenance of SC straw on soil surface are key-factors to increase soil C sequestration, nutrient-cycling and improve soil quality in SC fields (Cerri et al, 2011;Bordonal et al, 2012;Brandani et al, 2014). In addition, fertilization using organic residues from sugarcane industry (e.g., vinasse and filter cake) could be a feasible alternative to increase SOM (Brandani et al, 2014) and provide nutrients, especially K and P (Christofoletti et al, 2013;Prado et al, 2013) reducing the production costs with mineral fertilizers (Almeida Junior et al, 2011;Silva et al, 2014).…”

Multi-Analytical Interactions in Support of Sugarcane Agroecosystems Sustainability in Tropical Soils

“…As an alternative to mineral fertilization in sugarcane production fields, waste products from ethanol production (vinasse and filter cake), sewage sludge, green manures, inoculants of atmospheric N-fixing bacteria and phytohormones are commonly applied to the soil in the form of organic fertilizer to promote plant growth [46]. These organic fertilizers represent an important contribution of the N, P, K, and organic matter, mainly soil labile organic fractions, such as dissolved organic C and N, and others C-light organic fractions [47][48][49], in the sugarcane agroindustry [25]. Soil labile organic C can be defined as the soil organic matter fraction that sustains the soil food web and therefore directly influences nutrient cycles and many biologically related soil properties [50].…”

“…Although organic fertilizers are used to increase sugarcane productivity through nutrient availability to plants, they can also affect soil microbial community and physicochemical soil factors [7,14,20,52], and key biogeochemical processes associated with GHG emissions, such as decomposition, respiration, nitrification and denitrification [23,25,53]. Moreover, the use of organic residues has resulted in the increase of C and N labile organic forms [47][48][49], which has been used as soil quality indicator due to rapid alteration according to soil practice management [54]. It is generally assumed that plant litter and humus are the two most important Sugarcane -Technology and Research sources of dissolved organic matter in soils, and its release into solution occurs through physicochemical decomposition and leaching from litter and formation of humic substances [55].…”

“…Regarding the soil chemical factors, the K and S were negatively correlated with microbial biomass and the soil pH was positively correlated with microbial-C biomass. The long-term organic inputs has evidenced clear trend of increasing microbial-C biomass when compared with conventional practice management [47,56]. In turn, Dias [53] reported that vinasse can increase the abundance of nitrous oxide reductase (nosZ) gene but not the copy number of both nitrite reductase (nirK) and methyl coenzyme-M reductase (mcrA) genes in sugarcane soils.…”

Estimating soil carbon dynamics in intercrop and sole crop agroecosystems using the Century model

“…The extent to which the decomposed compounds are stabilized is a function of soil texture (Parton et al, 1988). Century was initially developed to simulate changes in SOC stocks in grasslands (Parton et al, 1988), but the model is also able to simulate agroecosystems (Ouyang et al, 2014;Brandani et al, 2015), forest ecosystems (Hashimoto et al, 2012), and agroforestry systems (Oelbermann and Voroney, 2011) in temperate and tropical environments. Century, therefore, has become one of the most widely used models due to its broad applicability.…”