Long‐Term Corn Residue Effects

Abstract

A better understanding of C turnover, with estimates of root‐derived C, is needed to manage soil C sequestration. The objective was to evaluate the long‐term treatment and environmental effects on unharvestable soil C components. Two N fertilizer treatments and a control were imposed during 29 yr of continuous corn (Zea mays L.) with stover removal as silage vs. stover return during grain harvest with moldboard plow (MB) tillage. Soil organic carbon (SOC) declined and natural 13C abundance (δ13C) increased during the 29‐yr period. Field averages of SOC and δ13C (0–30 cm) were 96.4 Mg ha−1 and −17.3‰ in 1965; respective values in 1995 were 78.9 Mg ha−1 and −16.6‰. Loss of SOC was greater with stover removed or no fertilization, but δ13C increased for all treatments. Stover yield (SY), SOC, and δ13C data were applied to a model to estimate unharvestable C and predict total source C (SC) input from corn. The SC for 29 yr totaled 172 to 189 Mg ha−1 when stover was harvested and 268 to 284 Mg ha−1 when stover was returned. The SC input from unharvestable sources was 1.8 times more than SC from aboveground stover when N was added and 1.7 when N was not added. The root‐to‐shoot ratio was 1.1 when N was added and 1.2 with no N. Only 5.3% of the SC was retained as SOC. Unharvestable C contributions to rhizodeposition are much larger than suggested from controlled studies including C‐enriched CO2 followed by soil respiration or CO2 efflux measurements.

Critical soil moisture range for a coffee crop in an oxidic latosol as affected by soil management

“…The use of plant residues resulting in an improvement in the physical properties of soil is found in several studies (Blainski et al, 2012;Mulumba and Lal, 2008;Olibone et al, 2010;Verma and Sharma, 2008), and also the use of intercropping, such as grasses in citrus crops (Fidalski et al, 2010). The maintenance of Brachiaria in the interrow is also important for the addition of carbon because rhizo-deposition can incorporate up to 1.8 times more carbon than chaff decomposition (Wilts et al, 2004).…”

Life cycle greenhouse gas emissions, fossil fuel demand and solar energy conversion efficiency in European bioethanol production for automotive purposes

“…There is evidence that due to their relatively slow break down rate, crop residues have a relatively good potential for maintaining soil carbon levels and that crop residue return to agricultural land is important for the sustainability of cropping systems [80,81]. It is also well known that when crop residues are consistently burned soil organic matter is reduced [80], which in turn may have a negative impact on future photosynthesis [48,49]. Such burning is now prohibited in many European countries [82] and will for this reason not be further considered here.…”

Connecting Soil Organic Carbon and Root Biomass with Land-Use and Vegetation in Temperate Grassland

“…Two major pathways of organic matter input—root tissue and exudates—directly involve plants [22]. Roots contribute to SOC pools through rhizodeposition [23] and the longer residence time of carbon from root tissue than shoot tissue [24]. Abiotic factors can also affect root growth and SOC.…”