Perennial Forages as Second Generation Bioenergy Crops

The lignocellulose in forage crops represents a second generation of biomass feedstock for conversion into energy-related end products. Some of the most extensively studied species for cellulosic feedstock production include forages such as switchgrass (Panicum virgatum L.), reed canarygrass (Phalaris arundinacea L.), and alfalfa (Medicago sativa L.). An advantage of using forages as bioenergy crops is that farmers are familiar with their management and already have the capacity to grow, harvest, store, and transport them. Forage crops offer additional flexibility in management because they can be used for biomass or forage and the land can be returned to other uses or put into crop rotation. Estimates indicate about 22.3 million ha of cropland, idle cropland, and cropland pasture will be needed for biomass production in 2030. Converting these lands to large scale cellulosic energy farming could push the traditional forage-livestock industry to ever more marginal lands. Furthermore, encouraging bioenergy production from marginal lands could directly compete with forage-livestock production

Effects of Tillage and Nitrogen Fertilizers on CH4 and CO2 Emissions and Soil Organic Carbon in Paddy Fields of Central China

Quantifying carbon (C) sequestration in paddy soils is necessary to help better understand the effect of agricultural practices on the C cycle. The objective of the present study was to assess the effects of tillage practices [conventional tillage (CT) and no-tillage (NT)] and the application of nitrogen (N) fertilizer (0 and 210 kg N ha−1) on fluxes of CH4 and CO2, and soil organic C (SOC) sequestration during the 2009 and 2010 rice growing seasons in central China. Application of N fertilizer significantly increased CH4 emissions by 13%–66% and SOC by 21%–94% irrespective of soil sampling depths, but had no effect on CO2 emissions in either year. Tillage significantly affected CH4 and CO2 emissions, where NT significantly decreased CH4 emissions by 10%–36% but increased CO2 emissions by 22%–40% in both years. The effects of tillage on the SOC varied with the depth of soil sampling. NT significantly increased the SOC by 7%–48% in the 0–5 cm layer compared with CT. However, there was no significant difference in the SOC between NT and CT across the entire 0–20 cm layer. Hence, our results suggest that the potential of SOC sequestration in NT paddy fields may be overestimated in central China if only surface soil samples are considered

Maize Production in a Changing Climate

Plant breeding and improved management options have made remarkable progress in increasing crop yields during the past century. However, climate change projections suggest that large yield losses will be occurring in many regions, particularly within sub-Saharan Africa. The development of climate-ready germplasm to offset these losses is of the upmost importance. Given the time lag between the development of improved germplasm and adoption in farmers’ fields, the development of improved breeding pipelines needs to be a high priority. Recent advances in molecular breeding provide powerful tools to accelerate breeding gains and dissect stress adaptation. This review focuses on achievements in stress tolerance breeding and physiology and presents future tools for quick and efficient germplasm development. Sustainable agronomic and resource management practices can effectively contribute to climate change mitigation. Management options to increase maize system resilience to climate-related stresses and mitigate the effects of future climate change are also discussed

Soil Spatial Variability: Structures, Models, and Their Effects on Crop Yield Variability

190 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2001.Principal component analysis showed that only 15 of 51 variables accounted for more than 80% of total soil variability. Component regression accounted for about 52%, and 39% of soybean and corn yields variability respectively. Particle size distribution and organic matter by influencing moisture and nutrient dynamics, were the most important factors determining yield variability in these soils.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD

Estimation of nocturnal CO₂ and N₂O soil emissions from changes in surface boundary layer mass storage

Annual budgets of greenhouse and other trace gases require knowledge of the emissions throughout the year. Unfortunately, emissions into the surface boundary layer during stable, calm nocturnal periods are not measurable using most micrometeorological methods due to non-stationarity and uncoupled flow. However, during nocturnal periods with very light winds, carbon dioxide (CO2) and nitrous oxide (N2O) frequently accumulate near the surface and this mass accumulation can be used to determine emissions. Gas concentrations were measured at four heights (one within and three above canopy) and turbulence was measured at three heights above a mature 2.5 m maize canopy from 23 July to 10 September 2015. Nocturnal CO2 and N2O fluxes from the canopy were determined using the accumulation of mass within a 6.3 m control volume and out the top of the control volume within the nocturnal surface boundary layer. Diffusive fluxes were estimated by flux gradient method. The total accumulative and diffusive fluxes during near-calm nights (friction velocities < 0.05 ms−1) averaged 1.16 µmol m−2 s−1 CO2 and 0.53 nmol m−2 s−1 N2O. Fluxes were also measured using chambers. Daily mean CO2 fluxes determined by the accumulation method were 90 to 130 % of those determined using soil chambers. Daily mean N2O fluxes determined by the accumulation method were 60 to 80 % of that determined using soil chambers. The better signal-to-noise ratios of the chamber method for CO2 over N2O, non-stationary flow, assumed Schmidt numbers, and anemometer tilt were likely contributing reasons for the differences in chambers versus accumulated nocturnal mass flux estimates. Near-surface N2O accumulative flux measurements in more homogeneous regions and with greater depth are needed to confirm the conclusion that mass accumulation can be effectively used to estimate soil emissions during nearly calm nights

Potential benefits and inherent dangers in cropping municipal waste dump sites – case studies in the City of Ibadan, Nigeria

The benefits derivable to crops from the high fertility status of municipal wastes dump sites and the dangers of heavy metal accumulation in crops planted therein were examined in three municipal refuse dumpsites namely, [Eleiyele (Site 1), Ring Road, (Site 2) and Bere (Site 3)] in Ibadan, Nigeria. The response of maize (Zea mays) to the soil nutrients and heavy metals were examined in the greenhouse and in the field. The plant nutrients in the three dump sites were quite adequate for maize growth and development but no germination of the test crop was observed in Site 3. Water (absorbed) and potassium nitrate (KNO3) (exchangeable) fractions of the heavy metals in the soils of the three sites were lower than the critical levels considered to be phytotoxic. However, the total extractable copper (Cu) (20.42mgkg-1) and zinc (Zn) (39.44mgkg-1) in the soils were higher in Site 3 than in the other dump sites. Site 3 soil also contained the highest population of cellulose degrading microorganisms. The concentrations of the heavy metals in plant tissue planted in the greenhouse experiment were low but high in plant tissue harvested in the field. Refuse dump site soils are important in Ibadan agricultural production but it is necessary that cropping is preceeded by soil test to determine nutrient and heavy metal concentrations. Keywords:Soil nutrients; Fertility status; Heavy metals; Municipal wastes [Global Jnl Environ Sci Vol.2(2) 2003: 102-105

Tillage and Nitrogen Rate Effects on Area- and Yield-Scaled Nitrous Oxide Emissions From Pre-Plant Anhydrous Ammonia

Precision-guided technologies enable corn (Zea mays L.) growers to apply pre-plant anhydrous ammonia (NH3) parallel to intended corn rows even when full-width tillage follows NH3 application. Close, but crop-safe, proximity of NH3 to corn rows may potentially increase N use efficiency and lower N requirements and nitrous oxide (N2O) emissions. Experiments in 2011 and 2012 on silty clay loam Mollisol near West Lafayette, IN, assessed area- and yield-scaled N2O emissions when spring pre-plant NH3 was applied at recommended (202 kg N ha−1) and reduced rate (145 kg N ha−1), in no-till (NT) and conventional tillage (CT) systems following NT soybean [Glycine max (L.) Merr.]. Each 12-cm deep NH3 band was positioned 15 cm from, and parallel to, intended corn rows using precision guidance. Nitrification of NH3 in application bands was 31% faster under CT than NT. Area- and grain yield-scaled N2O emissions were N rate dependent in both growing seasons. On average, CT+202 kg N resulted in highest area-scaled (mean = 2.45 kg N ha−1) and grain yield-scaled (mean = 360 g N Mg−1) N2O emissions. In contrast, CT+145 kg N had similar yield-scaled emissions as NT+202 and NT+145 kg N, and reduced area-scaled N2O emissions by 65, 45, and 19% respectively, relative to CT+202 kg N, NT+202 kg N, and NT+145 kg N treatments. These preliminary results suggest that reducing pre-plant NH3 rates by ∼30% under CT has the potential to reduce N2O emissions without significant yield declines in the CT phase of a NT–CT rotation, despite faster nitrification in CT