Stover Quality and Soil Organic Carbon in Long‐Term Nitrogen‐Fertilized Maize

Abstract

Nitrogen fertilization o en increases maize (Zea mays L.) grain yield but reduces the C/N ratio of stover returned to the soil, which may a ect the soil organic carbon (SOC) balance. is study evaluated the long-term e ect of N fertilization on maize grain yield, stover quality in terms of its C/N ratio, and its e ect on SOC. In addition, a simulation approach was used to account for the e ect of stover quality on its mineralization and SOC balance. Maize grain yield, stover production and quality, and SOC stock were measured during a 6-yr period (2006)(2007)(2008)(2009)(2010)(2011)(2012) in a long-term N fertilization experiment under continuous maize since 1994 in Paraná, Argentina. On average, grain yield ranged from 5.06 in 2011 to 9.10 Mg ha -1 in 2009. e N e ect on grain yield, signi cant in all seasons, was more important than the e ect on C stover production. In contrast, stover C/N ratio showed a linear decrease as a function of N fertilization. Changes in the stover C/N ratio were inversely proportional to the di erence between the N rate and the agronomical optimum nitrogen rate (AONR). Although N fertilization increased stover C inputs in 3 out of 6 yr, SOC stock remained unchanged. Simulation results indicate that the required stover amount to maintain the SOC stock increased as the C/N ratio decreased. Our results contribute to better understanding of the previous, controversial results of the N e ect on SOC and provide useful insights to develop or improve simulation models for SOC dynamics.

Nitrogen utilization efficiency in maize as affected by hybrid and N rate in late-sown crops

“…Since N upt did not differ among hybrids, the use of genotypes with an improved ability for N partitioning to grain may be an emerging strategy in environments with strong restrictions for late growth in order to reduce residual N in stover and undesirable environmental consequences. As has been showed recently, the N amount in involved in crop residue is a key factor in it mineralization, which influences the amount of C input required to maintain soil C balance close to neutral (Melchiori et al, 2014).…”

Development of a nitrogen recommendation tool for corn considering static and dynamic variables

“…A subsample of the residue was analyzed for C, N, and C:N ratio using the dry combustion method (LECO, 2008). Residue amount and quality for the other seasons were estimated from previously published grain yield and residue C:N relationships for Argentina (Melchiori et al, 2014).…”

Dryland Soil Carbon and Nitrogen Stocks in Response to Cropping Systems and Nitrogen Fertilization

“…Schemer et al [17] observed that crop rotation had a greater effect on SOC and STN than N fertilization. Other researchers [12,25], however, did not find significant effect of N fertilization on SOC and STN.…”