Multilocation Straw Removal Effects on Sugarcane Yield in South-Central Brazil

Abstract

Sugarcane straw is a crop residue that has a dual purpose and can be maintained on the fields or used to produce bioenergy. The straw retention in the field provides multiple ecosystem services, and the complex interactions between straw and yield responses are hard to predict by local studies. The aim of this study was to investigate the straw removal effects on sugarcane yield in southcentral Brazil. To achieve the objective, a set of 21 field studies was conducted in contrasting edaphoclimatic conditions. In addition, data of seven studies from the literature were included to build a more robust dataset. Since straw removal treatments were not homogeneous in all experiments, they were grouped as follows: NR, no removal (baseline treatment); LR, low removal; MR, moderate removal; and TR, total removal. To facilitate the data analysis, the experiments were gathered in four macroregions: southern Goiás, western São Paulo, central-eastern São Paulo, and northeastern São Paulo. The site location was the most effective individual factor to explain the straw removal effects on sugarcane yields. Compared with NR treatment, the average yield losses induced by LR, MR, and TR were 2, 10, and 13 Mg ha −1 in southern Goiás and 2, 4, and 6 Mg ha −1 in western São Paulo states, respectively. In other regions, no clear pattern was observed, and only site-specific effects were observed. Straw removal affected sugarcane yields in all soil types, but higher responses were observed under best conditions for sugarcane growth (i.e., clayey soils in southern Goiás). Our findings indicated harvesting season has a relevant role on determining yield responses to straw removal and younger ratoons are more responsive to straw removal. Conclusions from this study suggest straw removal recommendations cannot be designed based on isolated factors but require holistic and integrated knowledge to ensure that the straw amount left on field is enough to sustain multiple soil ecosystem services and crop yields.

Does straw retention sustain soil carbon stocks in Brazilian sugarcane fields?

“…Results of this study are consistent with previous long-term predictions obtained from modelling research conducted in Brazil (Carvalho et al, 2017b;Oliveira et al, 2017), and are in line with SOC declines reported in sites with corn stover removal around world (Johnson et al, 2014;Xu et al, 2019). Aligned with our findings, recent studies have shown that the maintenance of sugarcane straw on soil surface provides several soil ecosystem services, such as protection against soil erosion , favorable environment to microbiological processes (Pimentel et al, 2019;Tenelli et al, 2019), stabilization of aggregates (Castioni et al, 2019), nutrients cycling and reduction of fertilizer consumption (Cherubin et al, 2019), all of which having essential role to boost sugarcane crop yield (Carvalho et al, 2019).…”

“…Additionally, the lower SOC stocks in sandy soils can be associated with sugarcane productive potential of these areas. For example, Carvalho et al (2019) measured sugarcane yields in the same experimental areas and concluded that sandy soils produce 40% less biomass than clayey soils. The authors reported that the higher yields in clayey soils are linked to greater water availability and soil fertility, thus providing proper conditions for root growth and development.…”

Multilocation changes in soil carbon stocks from sugarcane straw removal for bioenergy production in Brazil

“…In addition to the fact that the lower SOC stocks in sandy soils are related to textural properties, this may also be associated with sugarcane productive potential of these areas. For example, Carvalho et al (2019) measured sugarcane yields in the same experimental areas and concluded that sandy soils produce 40% less biomass and crop residues than clay soils. The authors reported that the higher yields in clay soils are linked to greater water availability and soil fertility, thus providing proper conditions for root growth and development.…”

“…These results are also consistent with prior long‐term predictions from modelling research in Brazil (Carvalho, Hudiburg, et al, 2017; Oliveira et al, 2017), and are in line with SOC declines reported for corn ( Zea mays L.) stover removal around the world (Battaglia et al, 2020; Berhane et al, 2020; Johnson et al, 2014; Xu et al, 2019). Aligned with our findings, recent studies have shown that the maintenance of sugarcane straw on soil surface supports several soil ecosystem services, including decreasing soil erosion (Carvalho, Nogueirol, et al, 2017), creating more favorable environments for microbiological processes (Pimentel et al, 2019; Tenelli et al, 2019), stabilizing soil aggregates (Castioni et al, 2019), enhancing nutrient cycling and reducing fertilizer consumption (Cherubin et al, 2019), all which have an essential role in boosting sugarcane yield (Carvalho et al, 2009). By the way, what was the role of straw for each removal treatment?…”

Alterations in soil physical and hydraulic properties under sugarcane straw removal management: basis for assessment of ecosystem services related to water flow regulation and erosion control

“…In the Center-South region, which concentrates over 90% of total Brazilian production (CONAB, 2021), the burnt cane harvest system has been substituted by a system with mechanized harvesting of unburnt or "green" cane. In addition to the agronomic, environmental, and human health benefits, the transition to mechanized harvesting opened the possibility of using crop residues as raw material for cogeneration of electricity or production of cellulosic ethanol Carvalho et al, 2019 ;Aguiar et al, 2021), in addition to the already-used sugarcane bagasse. As the majority of sugarcane mills in the Center-South region are already energy-independent, and a growing number has been sending their surplus electricity to the national grid since 2013 (UNICA, 2020), the use of sugarcane straw to produce bioelectricity for commercialization is an interesting possibility to increase the financial sustainability of mills facing an economic crisis.…”