Nitrate leaching and soil nitrous oxide emissions diminish with time in a hybrid poplar short‐rotation coppice in southern Germany

Abstract

Kenya AbstractHybrid poplar short-rotation coppices (SRC) provide feedstocks for bioenergy production and can be established on lands that are suboptimal for food production. The environmental consequences of deploying this production system on marginal agricultural land need to be evaluated, including the investigation of common management practices i.e., fertilization and irrigation. In this work, we evaluated (1) the soil-atmosphere exchange of carbon dioxide, methane, and nitrous oxide (N 2 O); (2) the changes in soil organic carbon (SOC) stocks; (3) the gross ammonification and nitrification rates; and (4) the nitrate leaching as affected by the establishment of a hybrid poplar SRC on a marginal agricultural land in southern Germany. Our study covered one 3-year rotation period and 2 years after the first coppicing. We combined field and laboratory experiments with modeling. The soil N 2 O emissions decreased from 2.2 kg N 2 O-N ha À1 a À1 in the year of SRC establishment to 1.1-1.4 kg N 2 O-N ha À1 a À1 after 4 years. Likewise, nitrate leaching reduced from 13 to 1.5-8 kg N ha À1 a À1 . Tree coppicing induced a brief pulse of soil N 2 O flux and marginal effects on gross N turnover rates. Overall, the N losses diminished within 4 years by 80% without fertilization (irrespective of irrigation) and by 40% when 40-50 kg N ha À1 a À1 were applied. Enhanced N losses due to fertilization and the minor effect of fertilization and irrigation on tree growth discourage its use during the first rotation period after SRC establishment. A SOC accrual rate of 0.4 Mg C ha À1 a À1 (uppermost 25 cm, P = 0.2) was observed 5 years after the SRC establishment. Overall, our data suggest that SRC cultivation on marginal agricultural land in the region is a promising option for increasing the share of renewable energy sources due to its net positive environmental effects.

Species and Genotype Effects of Bioenergy Crops on Root Production, Carbon and Nitrogen in Temperate Agricultural Soil

“…Soil TN was a different matter, and we estimated losses of up to − 0.15 Mg TN ha −1 year −1 under Terra Nova but marginal increases of up to 1.0 Mg TN ha −1 year −1 under the other crops. We may presume that high N requirements of willows [58] were met in part by soil TN reserves in addition to fertiliser.…”

Environmental impacts of bioenergy wood production from poplar short‐rotation coppice grown at a marginal agricultural site in Germany

“…Hybrid poplars have exceptional vegetative regeneration abilities (Aylott et al ., ) and high biomass production rates and can be cultivated and adapted to a wide range of geographical conditions – especially in temperate climate (Fortier et al ., ). Established as SRC on marginal agricultural sites, they further have the potential to increase soil C sequestration (Anderson‐Teixeira et al ., ), while reducing soil nitrate (Díaz‐Pines et al ., ).…”

“…We focused our analysis on these two categories, which are the primary criteria in numerous papers that deal with the cultivation and the use of biomass for energy production (Cherubini & Strømman, ), because they address different environmental spheres (air and soil) and are often found to show significant differences between management regimes (McBride et al ., ). Our study addressed all phases of the technological and agronomic production of poplar wood chips, based on experimental (Díaz‐Pines et al ., ) and literature data (Burger, ) as well as data collections concerning technological activities (c.f. Schweier et al ., ) and the use of a database (Ecoinvent, ) in combination with simulation estimates (for 21 years) performed with the process‐based ecosystem model LandscapeDNDC (Haas et al ., ) and Umberto , a software which supports ISO compliant LCAs (IFU, ).…”

Greenhouse gas budget of a poplar bioenergy plantation in Belgium: CO2 uptake outweighs CH4 and N2O emissions

“…Although biomass from SRC might be a valuable option to partially replace fossil fuels, we lack knowledge of the greenhouse gas (GHG) balance associated with the operation of perennial SRC (Crutzen, Mosier, Smith, & Winiwarter, ; Díaz‐Pinés et al, ; Palmer, Forrester, Rothstein, & Mladenoff, ). Previous life cycle analyses of SRC plantations combined field measurements and modeling (Schweier et al, ), but ecosystem GHG fluxes have seldomly been quantified over multiple rotations of SRC on‐site (Gelfand et al, ; Harris et al, ).…”

“…Former land use, site‐specific soil properties and climate conditions influence GHG emissions from SRCs (Field, Marx, Easter, Adler, & Paustian, ; Whitaker et al, ). Site management, that is, the use of fertilizer, irrigation, and length of the rotation period, also influences the GHG balance (Carter et al, ; Díaz‐Pinés et al, ).…”