Crop residue chemistry, decomposition rates, and CO2 evolution in Bt and non-Bt corn agroecosystems in North America: a review

Abstract

Corn (Zea mays L.

Scientific Opinion on an application from Pioneer Hi‐Bred International and Dow AgroSciences LLC (EFSA‐GMO‐NL‐2005‐23) for placing on the market of genetically modified maize 59122 for food and feed uses, import, processing and cultivation under Regulation (EC) No 1829/2003

“…110 Bt-proteins do not act as antimicrobials but rather as insecticides with a narrow host specificity. During the relatively long period of scientific exploration of Bt-proteins and their potential biotechnological or agricultural applications, there has been no scientific report to the EFSA GMO Panel's knowledge that these proteins would exhibit adverse effects on bacteria or other microorganisms or interfere with microbial activities Yanni et al, 2010;Barriuso et al, 2012;Fließbach et al, 2012;Prischl et al, 2012). Therefore, there is no indication of a hazard from maize 59122 or its Cry34Ab1/Cry35Ab1 proteins to soil microorganisms and the ecosystem services they provide, including their contribution to biogeochemical processes.…”

Soil microbial properties in Bt (Bacillus thuringiensis) corn cropping systems

“…Residues of Bt corn have been shown to have higher lignin concentrations (Saxena and Stotzky, 2001) or C/N ratios (Flores et al, 2005) than conventional corn although it is not always the case (Tarkalson et al, 2008;Yanni et al, 2011). But in most studies (reviewed by Yanni et al, 2010), the rate and extent of decomposition of Bt crop residues is not different from that of non-Bt crop residues.…”

Effects of water management practices on residue decomposition and degradation of Cry1Ac protein from crop-wild Bt rice hybrids and parental lines during winter fallow season

“…Day (1983) demonstrated that the higher decay rates of leaf litter under flooded conditions were primarily due to high leaching losses that were attributed to continuous soaking rather than greater microbial activity. Yanni et al, (2010) also reported that the soluble fraction appeared to control the decomposition rate because leaves, which contain the highest percentage of the soluble fraction and the lowest C:N ratio, decomposed rapidly. It was reported that rice roots contained a higher content of recalcitrant components such as lignin and a lower content of decomposable components such as nonstructural carbohydrates compared with rice leaves and stems (Abiven et al, 2005).…”

“…For instance, the Cry genes in GM corn may alter litter quality and then influence litter decomposition and nutrient release (Flores et al, 2005;Yanni et al, 2011). The decomposition of voluminous crop residues is an important ecological factor in nutrient cycling and carbon sequestration in soils (Yanni et al, 2010). The estimated annual amount of rice straw in China is 188 million tonnes, but only a limited amount is used for animal feed and the remainder is returned directly to the soil (Wang et al 2006a), leading to large quantities of rice residues remaining in the field.…”