Core Ideas Annual crops produced a third more biomass and three times as much ethanol as perennials. Perennial crops used half as much nitrogen fertilizer as annual crops. Grain from most annual crops enhanced ethanol production per unit of biomass. Sweet sorghum produced substantially more ethanol than all other crops. Sorghum yielded more biomass and potential ethanol than corn in hot, dry years. Although energy crops could eventually supply a growing portion of cellulosic biofuel feedstocks, long‐term comparisons of annual and perennial crops are rare. An experiment was established in 2007 near Manhattan, KS, to compare biomass productivity and ethanol yield of perennial and annual crops. Perennial crops included three C4 grasses: switchgrass (Panicum virgatum L.), big bluestem (Andropogon gerardii Vitman), and miscanthus (Miscanthus sacchariflorus). Annual C4 crops were corn (Zea mays L.) in two rotations: continuous and rotated with soybean [Glycine max (L.) Merr.]; and five types of sorghum [Sorghum bicolor (L.) Moench]: photoperiod sensitive, sweet, dual purpose (grain and biomass), brown mid‐rib, and grain; all rotated with soybean. Annual crops produced 7 Mg ha−1 yr−1 more biomass than perennial crops throughout 11 yr, with sweet sorghum exceeding 22 Mg ha−1 yr−1, and 12 m3 ha−1 yr−1 of ethanol. Biomass yield of miscanthus approached 14 Mg ha−1 yr−1, essentially the same as for several annual crops but with half as much fertilizer nitrogen. Annual ethanol production from miscanthus and switchgrass was 3.6 m3 ha−1 yr−1, half as much as that of several annual crops that produced similar biomass yields. Big bluestem consistently produced the least biomass and ethanol, less than 7 Mg ha−1 yr−1 and 1.7 m3 ha−1 yr−1, respectively. Rotated corn averaged 7.1 m3 ha−1 yr−1 of ethanol. Eleven years of results indicate that annual corn and sorghum crops as well as perennial grasses such as miscanthus and switchgrass could play a role as potential bioenergy feedstocks in diversified production systems.

Sorghum is an important source of starch and fiber throughout the world. This chapter will focus on forage and biomass sorghum. Traits found in sorghum include photoperiod sensitivity and insensitivity, brown midrib, and brachytic dwarfism. Exceptional drought tolerance enables sorghum to produce high yields under limited water supply. The primary use for forage sorghum worldwide is animal feed, but sorghum may also be used as a dedicated energy crop for chemical production, direct combustion to produce heat, and anaerobic digestion to produce biogas. Sorghum's genetic diversity has not been fully exploited and could be the key to its future use in both traditional and new applications.

Current knowledge of yield potential and best agronomic management practices for perennial bioenergy grasses is primarily derived from small‐scale and short‐term studies, yet these studies inform policy at the national scale. In an effort to learn more about how bioenergy grasses perform across multiple locations and years, the U.S. Department of Energy ( US DOE )/Sun Grant Initiative Regional Feedstock Partnership was initiated in 2008. The objectives of the Feedstock Partnership were to (1) provide a wide range of information for feedstock selection (species choice) and management practice options for a variety of regions and (2) develop national maps of potential feedstock yield for each of the herbaceous species evaluated. The Feedstock Partnership expands our previous understanding of the bioenergy potential of switchgrass, Miscanthus, sorghum, energycane, and prairie mixtures on Conservation Reserve Program land by conducting long‐term, replicated trials of each species at diverse environments in the U.S. Trials were initiated between 2008 and 2010 and completed between 2012 and 2015 depending on species. Field‐scale plots were utilized for switchgrass and Conservation Reserve Program trials to use traditional agricultural machinery. This is important as we know that the smaller scale studies often overestimated yield potential of some of these species. Insufficient vegetative propagules of energycane and Miscanthus prohibited farm‐scale trials of these species. The Feedstock Partnership studies also confirmed that environmental differences across years and across sites had a large impact on biomass production. Nitrogen application had variable effects across feedstocks, but some nitrogen fertilizer generally had a positive effect. National yield potential maps were developed using PRISM ‐ ELM for each species in the Feedstock Partnership. This manuscript, with the accompanying supplemental data, will be useful in making decisions about feedstock selection as well as agronomic practices across a wide region of the country.

Sorghum is an important source of grain and fodder, forage and biomass throughout the world. In the United States, grain sorghum is the prominent crop; however, non-grain or forage sorghum plays an important role as a feedstock globally. Forage sorghum is phenotypically diverse with cultivars that are used primarily for silage, cultivars that may or may not include sudangrass that are primarily used for haying and grazing, and more recently, high-yielding and sweet cultivars that have been positioned for use as renewable feedstocks. Sorghum was quickly identified as one of the most appropriate dedicated energy crops. In addition, having scalable and well-understood production practices makes sorghum more acceptable than many lesser developed perennial grasses. Relative high yields make it an excellent choice over grain-based annuals, and because it is generally not used for human food, it is of less concern in the food-versus-fuel debate (Staggenborg et al., 2008). Sorghum has been used as a renewable feedstock to produce cellulosic ethanol, steam via combustion and methane via anaerobic digestion. Traits such as brown midrib (BMR) and brachytic dwarfism, and heat and drought tolerance make sorghum adaptable to many marginal environments.

Sweet sorghum is considered a promising alternative feedstock for ethanol production in the U.S. Southeast and Midwest. The most challenging issue in using sweet sorghum as a feedstock is the long-term storage of sweet sorghum juice for year-round supply of the fuel ethanol industry. As much as 20% of its fermentable sugars can be lost in three days after harvest due to bacterial activity. The purpose of this research was to evaluate some novel treatments to stabilize sweet sorghum juice for long-term storage. Sweet sorghum juice was homogenized at 32 kpsi and treated with ozone gas, and storage stability was evaluated by monitoring the chemical composition (fermentable sugar profile, organic acids, and ethanol contents) and microbial characteristics (total aerobic count and lactic bacterial count) of the treated juices stored at room temperature. Results from this research showed that high-pressure homogenizing and ozone treatment could significantly reduce both aerobic bacterial counts and lactic acid bacterial counts (2.5 log reduction in ABC and more than 3 log reduction in LAB) as evaluated using 3M Petrifilm. After storage for three months at room temperature, the microbial counts of the treated juice remained similar to 3 log lower than those in the untreated juices. The untreated juice became thick and sticky, and its sugar profile changed significantly, retaining only around 30% of its original content. Although the sugar profiles of high-pressure homogenized juices changed, they retained 80% to 92% of their original sugar contents.

Chapter 11 Impacts of Drought and/or Heat Stress on Physiological, Developmental, Growth, and Yield Processes of Crop Plants P. V. V. Prasad, P. V. V. Prasad Dep. of Agronomy, Kansas State University, ManhattanSearch for more papers by this authorS. A. Staggenborg, S. A. Staggenborg Dep. of Agronomy, Kansas State University, ManhattanSearch for more papers by this authorZ. Ristic, Z. Ristic USDA-ARS, Plant Science and Entomology Research Unit, Manhattan, KansasSearch for more papers by this author P. V. V. Prasad, P. V. V. Prasad Dep. of Agronomy, Kansas State University, ManhattanSearch for more papers by this authorS. A. Staggenborg, S. A. Staggenborg Dep. of Agronomy, Kansas State University, ManhattanSearch for more papers by this authorZ. Ristic, Z. Ristic USDA-ARS, Plant Science and Entomology Research Unit, Manhattan, KansasSearch for more papers by this author Book Editor(s):L.R. Ahuja, L.R. AhujaSearch for more papers by this authorV.R. Reddy, V.R. ReddySearch for more papers by this authorS.A. Saseendran, S.A. SaseendranSearch for more papers by this authorQiang Yu, Qiang YuSearch for more papers by this author First published: 22 December 2008 https://doi.org/10.2134/advagricsystmodel1.c11Citations: 22Book Series:Advances in Agricultural Systems Modeling AboutPDFPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShareShare a linkShare onFacebookTwitterLinked InRedditWechat Summary Drought and heat stress are among the two most important environmental factors influencing crop growth, development, and yield processes. A comprehensive understanding of the impact of drought and heat stress will be critical in evaluating the impact of climate change and climate variability on crop production. Both drought and heat stress influence an array of processes including physiological, growth, developmental, yield, and quality of crop. The objective of this review is to provide an overview of the influences of these two stresses on the above processes independently and in combination. Our review suggests a clear need of information on interactive effects of stresses particularly of drought and heat stress which mostly occur in combination. Both short- and long-term stresses can significantly influence growth and yield processes when stress occurs at sensitive stages. Crops are generally more sensitive to drought and/or heat stress during reproductive stages of development, which mainly influences seed numbers. Some of the important traits associated with drought- and/or heat-stress tolerance are indicated and discussed. The impacts of drought and heat stress are often different, and tolerance mechanisms may also be different. There is a wide range of crop modeling approaches (simple empirical models and more mechanistic models) that try to quantify the impact of stresses on growth, development, and yield and yield quality traits. These crop models should have the capability to quantify the impact of both short- and long-term stress events on growth, development, and yield processes. Modeling growth, development, sink-source relation, grain yield, and grain quality of crops can improve understanding of physiological and genetic nature of tolerance which can lead to increased grain yield and quality of crops. Improved models can enhance our capacity to predict crop performance in future climates and also to identify traits that can potentially be improved or exploited to obtain higher and more stable crop yields under stressed environments. Citing Literature Response of Crops to Limited Water: Understanding and Modeling Water Stress Effects on Plant Growth Processes, Volume 1 RelatedInformation

The current forage handling equipment in the cellulosic ethanol industry is severely limited by the low bulk density of baled and ground biomass. Low bulk density contributes to flowability problems and lack of maximizing trailer capacities. Biomass pelleting process can improve the bulk density and flowability characteristics of forages. The objectives of this research were to evaluate: (I) the energy requirements of grinding sorghum stalks, corn stover, wheat straw, and big bluestem through two different screen size openings, (2) the energy requirements of pelleting forages from the two grind sizes, (3) the physical properties of pelleted biomass, and (4) the costs associated with biomass processing, transportation, and storage. The two mill screen size openings (3.2 and 6.5 mm) were found to have significantly different energy consumptions for grinding step from each other. All four forage types, except for big bluestem and corn stover, were also found to have significantly different energy consumptions for grinding. Production rate through the 6.5 mm screen was almost three times higher than that of the 3.2 mm screen (average of 181.4 vs. 68 kg/h). Hammermill screen size opening (i.e., grind size) was found to have significant effects on energy consumption for pelleting process. The four forage types were also found to have significantly different energy consumptions from each other, except for big bluestem versus wheat straw (P=0.1192). Particle length for the 3.2 mm grind ranged from 0.15 to 0.18 cm, while the 6.5-mm grind ranged from 0.20 to 0.31 cm. Pelleting increased bulk density from 99.96 to 160.02 kg/m(3) for raw biomass grinds to 499.30 to 701.13 kg/m(3) for pelleted biomass. Pellet durability ranged from 93% to 98%. A cost analysis indicated that it would take roughly $22 extra per metric ton for the transportation, pre-processing, and storage of pelleted cellulosic biomass than corn grain. This cost is still almost half that of the cost for baled biomass.

Evaluating in field seeder performance is challenging and sometimes requires destructive methods. An alternative method for evaluating seeder performance based on nonlinear regression was developed. This method yields parameters that describe seeder performance, such as emergence rate, initial emergence data, and emergence percent. These parameters are easy to explain to the practitioner. The proposed method was compared to a widely used method to assess emergence rate. Results assessing emergence percent were comparable between the two methods. There were differences between the emergence rate index and emergence rate determined from the proposed method. These differences were expected since the emergence rate index encompasses more information than simply the rate of emergence.

i) Groundwater use rates continue: The letter states that “There is a systematic deviation (authors’ calculated use is increasing, whereas reported metered pumping data are decreasing)” and “is also markedly inconsistent with common experiences in western Kansas.” Yes, pumping rates decline as water tables fall. Yet, Butler et al. seem unaware of Kansas water use data served by the KGS’s Water Information Management and Analysis System portal (summed for counties in each agricultural district and plotted as red points in Fig. 1). It is clear …

Sorghum [Sorghum bicolor (L.) Moench] is one of four herbaceous dedicated bioenergy crops the U.S. Department of Energy identified as critical to annually produce one billion tons of dry biomass. Of these four crops, sorghum is unique as it is a drought-tolerant, annual crop established from seed that is readily tractable to genetic improvement. The purpose of this study was to assess the yield potential and stability of sorghums grown across diverse production environments in the USA. For this study, six sorghum genotypes (one cultivar, five hybrids) were grown in yield trials in seven locations in six states for 5 years (2008–2012). Variation in dry and fresh yield was attributable to not only genotypes, but also to the effects of year, location, and year × location. Even with the highest yielding genotype, environmental conditions were a major factor in determining the yield in a given year. This variability affects the consistency of the biomass supply for ethanol production. In general, the southeastern USA had the highest mean yields for fresh weight and dry weight, indicating that this area may be the most reliable for biomass production. A significant variation was detected among genotypes for fresh weight, dry weight, moisture content, and brix, revealing that sufficient variation within sorghum exists for continued improvement and that certain hybrids are more tractable for biomass/bioenergy production. With dedicated bioenergy sorghum germplasm and proper production environments, sorghum will be a valuable tool in the goal of the sustainable production of one billion tons of dry biomass each year in the USA.

Sorghum [Sorghum bicolor (L.) Moench] is ideally suited as an energy feedstock given its versatility as a single source of starch, sugar, and lignocellulose. Alkali oxides, halides and ash content can be problematic when feedstock is intended for combustion applications because these elements can lead to slagging and fouling of boilers. Solutions for counteracting the alkali content of herbaceous biomass include chemical addition to neutralize alkali, blending high-alkali biomass with low-alkali sources to achieve an acceptable ash-fusion temperature in the resulting mixture, and removal of the alkali content through washing techniques. The objective of this experiment was to investigate the effect of washing sorghum biomass with water to improve its quality for combustion. Biomass separated in 1-kg replicates were washed with 7.6, 15.2 and 22.8 L of water and analyzed for composition. Ash content was reduced by up to 20% while lignin content increased up to 53% with washing. Higher heating values significantly increased by washing and were inversely correlated with ash and positively correlated with lignin content. Nitrogen, chlorine, calcium, magnesium and potassium were reduced by washing. In contrast, carbon, hydrogen, silicon, aluminum, titanium, iron, sodium, sulfur (as % of ash), and phosphorus significantly increased by washing. When calculated, total alkali kg/GJ decreased with washing to levels close to those known to be acceptable for combustion. Further experiments should be performed to understand the economics of washing sorghum biomass at a commercial scale as well as the potential value of leachates within a closed-loop system of sorghum feedstock production. (C) 2013 Elsevier Ltd. All rights reserved.

Groundwater provides a reliable tap to sustain agricultural production, yet persistent aquifer depletion threatens future sustainability. The High Plains Aquifer supplies 30% of the nation's irrigated groundwater, and the Kansas portion supports the congressional district with the highest market value for agriculture in the nation. We project groundwater declines to assess when the study area might run out of water, and comprehensively forecast the impacts of reduced pumping on corn and cattle production. So far, 30% of the groundwater has been pumped and another 39% will be depleted over the next 50 y given existing trends. Recharge supplies 15% of current pumping and would take an average of 500-1,300 y to completely refill a depleted aquifer. Significant declines in the region's pumping rates will occur over the next 15-20 y given current trends, yet irrigated agricultural production might increase through 2040 because of projected increases in water use efficiencies in corn production. Water use reductions of 20% today would cut agricultural production to the levels of 15-20 y ago, the time of peak agricultural production would extend to the 2070s, and production beyond 2070 would significantly exceed that projected without reduced pumping. Scenarios evaluate incremental reductions of current pumping by 20-80%, the latter rate approaching natural recharge. Findings substantiate that saving more water today would result in increased net production due to projected future increases in crop water use efficiencies. Society has an opportunity now to make changes with tremendous implications for future sustainability and livability.

Environmental temperature directly influences the lipid profile produced by oilseeds. If growing temperatures increase, as is predicted by current models, the precise profile of lipids produced are likely to change. This paper develops models to predict lipid profiles as a function of growing temperature. Data relating to lipid profiles of soybean (Glycine max), spring canola (Brassica napus), spring camelina (Camelina sativa), and sunflower (Helianthus annuus) were gathered from the literature and evaluated to examine the influence of temperature on relative production of oleic, linoleic, and linolenic acid. For each crop, a set of linear regressions was used to correlate temperature during the grain fill, defined as 30 days before harvest, with the molar percentages of oleic, linoleic, and linolenic acid present. An increase in temperature from 10 to 40°C resulted in an increase in the production of oleic acid and a decrease in the production of linoleic and linolenic acid in soybeans, canola, and sunflowers. Over the range of data available, the lipid profile of camelina was temperature insensitive. To test the validity of the correlations, the four crops were grown in a field study in Manhattan, Kansas simultaneously, in the same environment, in 2011. The correlations accurately predicted the field data for soybean, canola, and camelina but not for sunflower. The correlation for sunflower under-predicted the molar amount of oleic acid and over-predicted the molar amount of linoleic acid. This study indicates increasing growing temperatures from 10 to 40°C will result in more monounsaturated oils and less polyunsaturated oils in soybean, canola, and sunflower.

Densification of bulky forages by pelleting reduces their transportation, handling, and storage costs. Because of high shearing force and frictional heating during the pelleting process, it is hypothesized that pelleting of lignocellulosic biomass could also partially deconstruct its complex structure and facilitate bioethanol production. In this study, pelleted wheat straw, corn stover, big bluestem, and sorghum stalk were evaluated for sugars and ethanol production, and compared with those of unpelleted biomasses. Mass recovery after alkali pretreatment increased by 14%, 11%, 2%, and 5%, respectively, in unpelleted biomasses. Lignin content reduced significantly more in pelleted samples for all types of biomass, except sorghum stalk. Volumetric productivity of enzymatic hydrolysis was 23%, 21%, 20% and 12% higher, respectively, in pelleted samples; ethanol yield on the basis of released sugars did not differ significantly between pelleted and unpelleted samples. These results indicate that the pelleting process led to better enzymatic hydrolysis of pretreated biomasses without affecting the quality of sugars for fermentation. However, overall yield of ethanol from the raw biomass was not significantly higher in pelleted biomasses because of higher mass loss during pretreatment process. In our study, we propose a schematic for complete utilization of various byproducts for enhanced economic viability. (C) 2013 Elsevier B.V. All rights reserved.

In this study, Surface Energy Balance Algorithm for Land (SEBAL) was evaluated for its ability to derive aerodynamic components and surface energy fluxes from very high resolution airborne remote sensing data acquired during the Bushland Evapotranspiration and Agricultural Remote Sensing Experiment 2008 (BEAREX08) in Texas, USA. Issues related to hot and cold pixel selection and the underlying assumptions of difference between air and surface temperature (dT) being linearly related to the surface temperature were also addressed. Estimated instantaneous evapotranspiration (ET) and other components of the surface energy balance were compared with measured data from four large precision weighing lysimeter fields, two each managed under irrigation and dryland conditions. Instantaneous ET was estimated with overall mean bias error and root mean square error (RMSE) of 0.13 and 0.15 mm h (1) (23.8 and 28.2%) respectively, where relatively large RMSE was contributed by dryland field. Sensitivity analysis of the hot and cold pixel selection indicated that up to 20% of the variability in ET estimates could be attributed to differences in the surface energy balance and roughness properties of the anchor pixels. Adoption of an excess resistance to heat transfer parameter model into SEBAL significantly improved the instantaneous ET estimates. Published by Elsevier Ltd.

Dedicated bioenergy crops such as perennial warm‐season grasses (WSGs) may reduce soil erosion and improve soil properties while providing biomass feedstock for biofuel. We quantified impacts of perennial WSGs and row crops on soil wind erodibility parameters (erodible fraction, geometric mean diameter of dry aggregates, and aggregate stability) and soil organic carbon (SOC) concentration under a dedicated bioenergy crop experiment in eastern Kansas after 4 and 5 yr of management. Soil properties were measured under switchgrass (Panicum virgatum L.), big bluestem (Andropogon gerardii L.), miscanthus (Miscanthus × giganteus), and annual row crops including continuous corn (Zea mays L.), photoperiod sorghum [Sorghum bicolor (L.) Moench.], sweet sorghum, and grain sorghum. Perennial WSGs reduced wind erodible fraction by 1.08 to 1.16 times compared with row crops. The geometric mean diameter of dry aggregates under switchgrass and miscanthus was 2.8 to 4.5 times greater than under row crops. Dry soil aggregate stability under miscanthus and big bluestem was greater than under row crops. After 5 yr, differences in SOC concentration between WSGs and row crops were not statistically significant for the 0‐ to 15‐cm depth. Photoperiod sensitive and sweet sorghum had greater biomass yield than WSGs. In 2011, miscanthus yielded more biomass than corn by 5.3 Mg ha–1. Overall, growing dedicated bioenergy crops can reduce the soil’s susceptibility to wind erosion but may not significantly increase SOC concentration in this region in the short term.

Integrated environmental modeling enables the development of comprehensive simulations by compositing individual models within and across disciplines. The Simple Script Wrapper (SSW), developed here, provides a foundation for model linkages and integrated studies. The Open Modeling Interface (OpenMI) enables model integration but it is challenging to incorporate scripting languages commonly used for modeling and analysis such as MATLAB, Scilab, and Python. We have developed a general-purpose software component for the OpenMI that simplifies the linking of scripted models to other components. Our solution enables scientists to easily make their scripting language code linkable to OpenMI-compliant models fostering collaborative, interdisciplinary integrated modeling. The simplicity afforded by our solution is presented in a case study set in the context of irrigated agriculture. The software is available online as supplementary material and includes an example that may be followed to employ our methods.

Corn ( Zea mays L.) yield has increased from about 1.5 Mg ha −1 in the early 1900s to 8.5 Mg ha −1 in the beginning of the 2000s in the United States. Information about yield and management changes in irrigated and dryland corn yields for the hybrid era is scarce. The objective of the present study was to determine the magnitude of yield and management changes in irrigated and dryland corn from 1939 through 2009. Data from selected irrigated and dryland corn performance trials conducted in Kansas from 1939 through 2009 were analyzed. On average, corn yields have increased at rate of 90 kg ha −1 yr −1 in dryland and 120 kg ha −1 yr −1 in irrigated trials. Corn yield changes from one decade to another were not similar for the seven decades considered. Both irrigated and dryland yields increased significantly at least every two decades until the last three, during which dryland yields stagnated. Changes in hybrid technology and changes in crop management factors, such as a decrease in planting and harvesting date by about a quarter of a day yr −1 , increased planting density at the rate of 597 plants ha −1 yr −1 , and increased N and P fertilizer rates by 2.6 and 0.40 kg ha −1 yr −1 , respectively, were found for the same time period in dryland corn. In addition, climate changes contributed to yield increases in the past through increased total rainfall, average monthly minimum and maximum temperature in March, and decreased maximum temperature from July through September.