Engineering, nutrient removal, and feedstock conversion evaluations of four corn stover harvest scenarios

Crop residue has been identified as a near-term source of biomass for renewable fuel, heat, power, chemicals and other bio-materials. A prototype one-pass harvest system was used to collect residue samples from a corn (Zea mays L.) field near Ames, IA. Four harvest scenarios (low cut, high-cut top, high-cut bottom, and normal cut) were evaluated and are expressed as collected stover harvest indices (CSHI). High-cut top and high-cut bottom samples were obtained from the same plot in separate operations. Chemical composition, dilute acid pretreatment response, ethanol conversion yield and efficiency, and thermochemical conversion for each scenario were determined. Mean grain yield in this study (10.1 Mg ha−1 dry weight) was representative of the average yield (10.0 Mg ha−1) for the area (Story County, IA) and year (2005). The four harvest scenarios removed 6.7, 4.9, 1.7, and 5.1 Mg ha−1 of dry matter, respectively, or 0.60 for low cut, 0.66 for normal cut, and 0.61 for the total high-cut (top+bottom) scenarios when expressed as CSHI values. The macro-nutrient replacement value for the normal harvest scenario was $57.36 ha−1 or$11.27 Mg−1. Harvesting stalk bottoms increased stover water content, risk of combine damage, estimated transportation costs, and left insufficient soil cover, while also producing a problematic feedstock. These preliminary results indicate harvesting stover (including the cobs) at a height of approximately 40 cm would be best for farmers and ethanol producers because of faster harvest speed and higher quality ethanol feedstock

Analysis of five simulated straw harvest scenarios

. Analysis of five simulated straw harvest scenarios. Canadian Biosystems Engineering/Le ge´nie des biosyste`ms au Canada 50: 2.27Á2.35. Almost 36 million tonnes (t) of cereal grains are harvested annually on more than 16 million hectares (ha) on the Canadian prairies. The net straw production varies year by year depending upon weather patterns, crop fertility, soil conservation measures, harvest method, and plant variety. The net yield of straw, after discounting for soil conservation, averages approximately 2.5 dry (d)t ha (1 . Efficient equipment is needed to collect and package the material as a feedstock for industrial applications. This paper investigates the costs, energy input, and emissions from power equipment used for harvesting straw. Five scenarios were investigated: (1) large square bales, (2) round bales, (3) large compacted stacks (loafs), (4) dried chops, and (5) wet chops. The baled or loafed biomass is stacked next to the farm. Dry chop is collected in a large pile and wet chop is ensiled. The baling and stacking cost was $21.47 dt (1 (dry tonne), with little difference between round and large square baling. Loafing was the cheapest option at$17.08 dt (1 and wet chop followed by ensiling was $59.75 dt -1 . A significant portion of the wet chop cost was in ensiling. Energy input and emissions were proportional to the costs for each system, except for loafing, which required more energy input than the baling systems. As a fraction of the energy content of biomass (roughly 16 GJ dt (1 ), the energy input ranged from 1.2% for baling to 3.2% for ensiling. Emissions from the power equipment ranged from 20.3 kg CO 2 e dt (1 to more than 40 kg CO 2 e dt (1 . A sensitivity analysis on the effect of yield on collection costs showed that a 33% increase in yield reduced the cost by 20%. Similarly a sensitivity analysis on weather conditions showed that a 108C cooler climate extended the harvest period by 5Á10 days whereas a 108C warmer climate shortened the harvest period by 2Á3 days

Rates of sustainable forest harvest depend on rotation length and weathering of soil minerals

Abstract Removals of forest biomass in the northeastern US may intensify over the coming decades due to increased demand for renewable energy. For forests to regenerate successfully following intensified harvests, the nutrients removed from the ecosystem in the harvested biomass (including N, P, Ca, Mg, and K) must be replenished through a combination of plant-available nutrients in the soil rooting zone, atmospheric inputs, weathering of primary minerals, biological N fixation, and fertilizer additions. Few previous studies (especially in North America) have measured soil nutrient pools beyond exchangeable cations, but over the long rotations common in this region, other pools which turn over more slowly are important. We constructed nutrient budgets at the rotation time scale for three harvest intensities and compared these with detailed soil data of exchangeable, organic, and primary mineral stocks of in soils sampled in 15 northern hardwood stands developed on granitic till soils in the White Mountain region of New Hampshire, USA. This comparison can be used to estimate how many times each stand might be harvested without diminishing productivity or requiring fertilization. Under 1990s rates of N deposition, N inputs exceeded removals except in the most intensive management scenario considered. Net losses of Ca, K, Mg, and P per rotation were potentially quite severe, depending on the assumptions used.Biologically accelerated soil weathering may explain the lack of observed deficiencies in regenerating forests of the region. Sites differed widely in the long-term nutrient capital available to support additional removals before encountering limitations (e.g., a fourfold difference in available Ca, and a tenfold difference in weatherable Ca). Intensive short-rotation biomass removal could rapidly deplete soil nutrient capital, but traditional long rotations, even under intensive harvesting, are unlikely to induce nutrient depletion in the 21st century. Weatherable P may ultimately limit biomass production on granitic bedrock (in as few as 6 rotations). Understanding whether and how soil weathering rates respond to nutrient demand will be critical to determining long-term sustainability of repeated intensive harvesting over centuries

Modeling winter severity and harvest of moose: impacts of nutrition and predation

Thesis (M.S.) University of Alaska Fairbanks, 2013Climate change is expected to have both positive and negative impacts on northern ungulate populations. Moose (Alces alces) will likely benefit from an increase in the growing season length and frequency of wildfire. However, increases in extreme weather events may result in moose population declines, particularly for nutritionally stressed moose populations. Management strategies to reduce the nutritional stress of populations may become increasingly important. We used stage-structured population models to examine the impact of deep-snow events on moose population trajectories and evaluated female harvest strategies designed to mitigate nutritional stress by decreasing intraspecific competition. Population trajectories were primarily influenced by young adult and prime adult survival. Populations held at low density by predation are likely buffered against the effects of severe weather events, whereas nutritionally stressed populations are vulnerable to population declines from the same environmental conditions. Harvest of cow-calf pairs may be an effective way to maximize harvestable yield and maintain population resilience when nutritional condition is poor. Moose population abundance over the long-term may become more variable due to the effects of climate change. Future modeling needs to incorporate alternative harvest and climate scenarios to help us better understand how we can promote moose population resilience.Chapter 1: General introduction -- Chapter 2: Population models of Interior Alaska moose: impacts of nutrional condition on responses to winter severity and potential management strategies -- Abstract -- Introduction -- Methods -- Model structure -- Model parameterization -- Model performance -- Sensitivity of population growth rate to changes in vital rates -- Projected increases in deep snow years -- Snow depth -- Population responses to deep snow events -- Population responses to female harvest scenarios -- Results -- Model performance -- Sensitivity of population growth rate to changes in vital rates -- Population responses to deep snow events -- Population responses to female harvest scenarios -- Discussion -- Population responses to deep snow events -- Population responses to female harvest scenarios -- Management implications -- Acknowledgments -- References -- Chapter 3: General conclusions -- References

Alternatives for Drought-damaged Corn—Grain Crop or Forage

As people reflect on the reasons for the irregular development and poor grain production in Iowa this year, the next important questions relate to evaluation of crops in individual fields and planning when and how to harvest them to the greatest economic advantage. This evaluation involves reviewing normal crop growth and development, assessing the condition of the crops in individual fields relative to normal, and to think through several harvest scenarios such as: Will this field have a harvestable grain crop? Are there concerns about the crops? What use or management alternatives do I have

Alternatives for Drought-damaged Soybeans—Bean Crop or Forage

As people reflect on the reasons for the irregular development and poor soybean production in Iowa this year, the next important questions relate to evaluation of crops in individual fields and planning when and how to harvest them to the greatest economic advantage. This evaluation involves reviewing normal crop growth and development, assessing the condition of the crops in individual fields relative to normal and to think through several harvest scenarios. Will this field have a harvestable soybean crop? Are there concerns about the crops? What use or management alternatives do I have

Impacts of crop, biomass harvest systems, and nutrient management on field and subsurface drainage water quality

Grain-crop biomass and perennial grass biomass are of particular interest for their use in bioenergy production systems. Nutrient needs, particularly nitrogen and phosphorus, change with varying cropping systems, harvest systems, and rates of fertilizer application. Furthermore, manure generated from livestock production can be a viable nutrient source for cropping systems, reducing the need for commercial fertilizers. The primary focus of this study was to investigate nutrient loss, primarily nitrate-nitrogen loss, in subsurface drainage water under a variety of cropping, nutrient management, and harvest scenarios. Overall crop yields and biomass production were also evaluated

Impacts of Crop, Biomass Harvest Systems, and Nutrient Management on Yield and Subsurface Drainage Water Quality

Grain-crop biomass and perennial grass biomass are of particular interest for their use in bioenergy production systems. Nutrient needs, particularly nitrogen and phosphorus, change with varying cropping systems, harvest systems, and rates of fertilizer application. Furthermore, manure generated from livestock production can be a viable nutrient source for cropping systems, reducing the need for commercial fertilizers. The primary focus of this study was to investigate nutrient loss, primarily nitrate-nitrogen loss, in subsurface drainage water under a variety of cropping, nutrient management, and harvest scenarios. Overall crop yields and biomass production were also evaluated

Optimizing the environmental sustainability of alternative post-harvest scenarios for fresh vegetables: A case study in Spain

The aim of this research is to define different scenarios that optimize the environmental sustainability of the postharvest stage of vegetable products (cauliflower and brassicas mix). These scenarios considered different packaging materials; energy generation technologies for the processing plant (standard electricity mix vs. renewable options); organic waste management (composting, anaerobic digestion, and animal feeding); and refrigerated transportation (local, national, and international, using diesel, natural gas, and hybrid trucks and railway). The analysis has been carried out based on a foreground inventory provided by a company that operating internationally, in accordance with the International Organization for Standardization (ISO) 14,040 methodological framework and following the latest Product Environmental Footprint (PEF) protocols. The analysis describes four midpoint categories, single score (SS) using EF3.0 life cycle impact assessment (LCIA) methodology and the Cumulative Energy Demand. The carbon footprint (CF) of the post-harvest stage for a base case scenario ranged between 0.24 and 0.29 kg CO2 eq/kg of vegetable, with a strong contribution associated to the production of packaging materials (57.8–65.2 %) and the transport stage (national range in conventional diesel vehicles) (31.5–38.0 %). Comparatively, lower emissions were associated with the energy consumed at the processing factory (up to 4.1%) while the composting of organic waste management produced some impact savings (up to−3.5 %). Although certain differences were observed, the dominance of the transport stage and the packaging materials is sustained in all the other environmental impact and energy categories evaluated. The most effective measures to reduce the environmental footprint of the post-harvest stage involve: i) using reusable packaging materials; ii) reducing the transport range and using vehicles running on natural gas or hybrid technologies; iii) the incorporation of renewable energy to supply the factory; and iv) the utilization of the organic residues in higher value applications such as animal feeding. Implementing the measures proposed in this study would reduce the post-harvest CF of fresh vegetables by 90 %.This research was funded by RTI2018-099139-B-C21 from Spanish Ministry of Science and Innovation - National Research Agency (MCIN/AEI/10.13039/501100011033) and by “ERDF A way of making Europe”, of the “European Union”. Laura Rasines acknowledges financial support for PRE 2019-090573 grant by MCIN/AEI and by “ESF Investing in your future”