<p>Renewable bioenergy feedstocks offset the demand for conventional petrol... more <p>Renewable bioenergy feedstocks offset the demand for conventional petroleum-based energy resources. Switchgrass (Panicum virgatum L.) is a warm-season perennial C4 grass that has been utilized for lingo-cellulosic ethanol production and direct energy via combustion. However, little is known about its potential as a feedstock in the semi-arid northern Great Plains USA, including the impact of N fertilizer application on biomass production and on environmental quality. A field study initiated in 2009 seeded ‘Sunburst’ switchgrass into 12.2 m by 30.5 m plots. Split plots randomized within each main plot included fertilizer N broadcast each spring at 0, 28, 56, and 84 kg N per ha as urea, with four treatment replicates. Aboveground biomass, allowing a 20 cm stubble height, was harvested, weighed, and dried at 55 deg C each fall beginning in 2011 from four randomly selected 0.25 m sq areas. Soil cores were taken to a depth of 1.2 m in fall 2018, air-dried, and analyzed for soil nitrate. Switchgrass biomass ranged from 1.8 to 12.3 Mg per ha. In most years, N application increased switchgrass biomass, but response to N rates above 28 kg per ha was inconsistent. Biomass from fertilized switchgrass averaged 6.5 Mg per ha compared to 4.4 Mg per ha for the unfertilized control.  Soil nitrate levels indicated the potential of (over)fertilization of switchgrass feedstocks to impact water resources in semi-arid environments.</p>
Roots help in soil water and nutrient uptake and provide carbon (C) input for soil C sequestratio... more Roots help in soil water and nutrient uptake and provide carbon (C) input for soil C sequestration, but information on root biomass of bioenergy perennial grasses is lacking. Root/shoot ratios are used to estimate crop root biomass and C inputs, but the values for perennial grasses are also scanty. We examined root biomass, root/shoot ratios, and soil water contents to a depth of 120 cm after grass harvest in the fall for three bioenergy perennial grasses applied with four nitrogen (N) fertilization rates from 2011 to 2013 in the northern Great Plains, USA. Perennial grasses were intermediate wheatgrass (Thinopyrum intermedium [Host] Barkworth and Dewey), smooth bromegrass (Bromus inermis L.), and switchgrass (Panicum virgatum L.), and N fertilization rates were 0, 28, 56, and 84 kg N ha−1. Root biomass declined with depth and about 60% of the total biomass was located at 0-15 cm where intermediate wheatgrass and switchgrass had higher biomass than smooth bromegrass in 2011. Shoot biomass was greater in intermediate wheatgrass in 2011 and in switchgrass in 2013 than other grasses and increased with increased N rates. Root/shoot ratio was greater in switchgrass than other grasses at 0-120 cm in 2011, but was greater in smooth bromegrass than switchgrass at 0-60, 0-90, and 0-120 cm in 2012 and 2013. Mean root/shoot ratios across N rates and years were not different among grasses and varied from 1.54 at 0-15 cm to 2.54 at 0-120 cm, which were substantially greater than 0.15 and 0.33, respectively, observed for spring wheat (Triticum aestivum L.). Soil water content increased with depth and was greater under switchgrass than other grasses at 0-120 cm in 2011 and 2013. Water content varied with N rate at various soil depths and years. Root biomass was negatively correlated with soil water content (r = −0.56, P = 0.03, n = 15). Because of greater root and shoot biomass, intermediate wheatgrass reduced soil water content due to increased water uptake and will likely provide more C inputs for soil C sequestration from belowground biomass compared to smooth bromegrass and spring wheat.
Nitrogen balance provides a measure of agroecosystem performance and environmental sustainability... more Nitrogen balance provides a measure of agroecosystem performance and environmental sustainability by taking into accounts of N inputs and outputs and N retention in the soil. The objective of this study was to evaluate N balance based on N inputs and outputs and soil N sequestration after 7 yr in response to five dryland crop rotations (two 4-yr stacked and two 4-yr alternate-year rotations and one monocropping) and two cultural practices arranged in a split-plot design in the northern Great Plains, USA. Stacked rotations were durum (Triticum turgidum L.)-durum-canola (Brassica napus L.)-pea (Pisum sativum L.) (D-D-C-P) and durum-durum-flax (Linum usitatissimum L.)-pea (D-D-F-P). Alternate-year rotations were durum-canola-durum-pea (D-C-D-P) and durum-flax-durum-pea (D-F-D-P). Monocroppping was continuous durum (CD). Cultural practices were traditional (conventional till, recommended seed rate, broadcast N fertilization, and reduced stubble height) and ecological (no-till, increased seed rate, banded N fertilization, and increased stubble height). Total annual N input due to N fertilization, pea N fixation, atmospheric N deposition, crop seed N, and nonsymbiotic N fixation was lower in CD than other crop rotations, regardless of cultural practices. Total N output due to crop grain N removal and N losses due to denitrification, volatilization, plant senescence, N leaching, gaseous N (NO x) emissions, and surface runoff was lower in traditional CD and D-F-D-P than traditional D-C-D-P and ecological D-C-D-P, D-D-C-P, and D-F-D-P. Nitrogen sequestration rate at 0-125 cm from 2005 to 2011 ranged from 40 kg N ha À1 yr À1 for ecological D-D-F-P to 52 kg N ha À1 yr À1 for ecological CD. Nitrogen balance ranged from À39 to À36 kg N ha À1 yr À1 with CD compared to 9-25 kg N ha À1 yr À1 with other crop rotations in both cultural practices. Because of reduced reliance on external N inputs and increased grain N removal, N flow, and N surplus, crop rotations with legumes, nonlegumes, and oilseed crops in the rotation can be productive and environmentally sustainable compared with monocropping, regardless of cultural practices.
All rights reserved. No part of this periodical may be reproduced or transmitted in any form or b... more All rights reserved. No part of this periodical may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher.
The Great Plains region of the United States is an area of widespread dryland crop production, wi... more The Great Plains region of the United States is an area of widespread dryland crop production, with wheat being the dominant crop. Precipitation in the region ranges from 300 to 500 mm annually, with the majority of precipitation falling during hot summer months. The prevailing cropping system is a two-year rotation of wheat and summer fallow. The adoption of no-till practices has resulted in greater precipitation storage and use efficiency, which has led to greater cropping intensity, higher productivity, more diverse crop rotations, and improvements in soil properties. In Colorado, for example, a no-till rotation of winter wheat-maize-fallow increased total annualized grain yield by 75% compared to winter wheat-summer fallow. Soil erosion was reduced to just 25% of that from a conventional tillage wheat-summer fallow system. The primary challenge with reducing fallow frequency is the increase in yield variability and risk of crop failure. Improved approaches for choosing crop or fallow are being developed based on soil water content and forecasted weather. Development of alternative crops, crop rotations, and integrated livestock systems that are sustainable from both economic and ecological perspectives is an ongoing effort. Other research is addressing adaptation of cropping practices to climate change and the potential for dryland biomass crop production for the developing biofuel industry.
Brassicaceae oilseed crops can provide rotation benefits to dryland wheat (Triticum aestivum L.) ... more Brassicaceae oilseed crops can provide rotation benefits to dryland wheat (Triticum aestivum L.) and supply feedstock for biofuel production. However, growers face decisions about what oilseed crop is best suited for an environment. The objective of this study was to determine how varying production environments affect the agronomic performance of modern cultivars of six Brassicaceae crop species and identify ideal genotypes for seven growing environments spanning four ecoregions. A field experiment was replicated in Colorado,
Available water and N fertility are primary constraints to crop production in the northern Great ... more Available water and N fertility are primary constraints to crop production in the northern Great Plains of the USA. A field trial was initiated in 2004 to compare four crop rotations in a complete factorial of two tillage and two management systems. Rotations were continuous spring wheat (SW), pea-SW, barley hay-pea-SW, and barley hay-corn-pea-SW. Tillage systems were no till and field cultivator tillage, while management systems were conventional and ecological. Conventional management included broadcast nitrogen fertilizer, standard seeding rates, and short stubble height. Ecological management practices varied by crop, and included banded nitrogen fertilizer for cereals, increased seeding rate, delayed planting date for SW, and taller stubble height. Continuous SW grain yield was 26% lower than SW in more diverse rotations. Pea grain yield was 18% lower in 2-yr rotations than in more diverse rotations. Ecologically managed SW yielded 29% less than conventionally managed SW, presu...
The quality of this reproduction is dependent upon the quality of the copy submitted. Broken or i... more The quality of this reproduction is dependent upon the quality of the copy submitted. Broken or indistinct print, colored or poor quality illustrations and photographs, print bleed-through, substandard margins, and improper alignment can adversely affect reproduction. In the unlikely event that the author did not send a complete manuscript and there are missing pages, these will be noted. Also, if unauthorized copyright material had to be removed, a note will indicate the deletion.
<p>... more <p>Better management practices have been used to increase soil water storage and reduce evaporation from the soil surface to optimize crop water use efficiency (WUE) in irrigated agriculture. A field study was conducted to evaluate the effect of  conventional tillage (CT), No-till (NT) and strip tillage (ST) practices on yield, water use (WU) and WUE of sugarbeet (Beta vulgaris L.) on a clay loam soil under over-head sprinkler irrigation system in the northern Great Plains. Tillage treatments were replicated five times in a randomized block design. Seasonal WU and WUE for sugarbeet root and sucrose yield were determined for the 2018 and 2019 growing seasons according to the water balance and WUE equations under three tillage practices. Results showed that no significant differences due to tillage treatment were found for crop WU, root yield, sucrose yield, and WUE for sugarbeet root and sucrose in 2018 and 2019 growing seasons. In 2019, the average value of WU across three tillage systems (616 mm) was significantly greater relative to 2018 (468 mm) due to atypical large rainfalls (218mm) occurred in September of 2019. Consequently, WUE values for both root and sucrose yield in 2019 under CT, NT, and ST were significantly greater than those in 2018. While NT and ST practices are promising alternative to CT for agricultural production in this region, further research is needed prior to making any recommendation.</p>
Information on the long-term effect of management practices on soil C and N stocks is lacking. An... more Information on the long-term effect of management practices on soil C and N stocks is lacking. An experiment was conducted from 2004 to 2011 in the northern Great Plains, USA to examine the effects of tillage, crop rotation, and cultural practice on annualized crop residue (stems + leaves) returned to the soil and grain yield, and soil total C (STC) and total N (STN) stocks at the 0-120 cm depth. Tillage practices were no-tillage (NT) and conventional tillage (CT) and crop rotations were continuous spring wheat ( L.) (CW), spring wheat-pea ( L.) (W-P), spring wheat-barley ( L.) hay-pea (W-B-P), and spring wheat-barley hay-corn ( L.)-pea (W-B-C-P). Cultural practices were traditional (conventional seed rates and plant spacing, conventional planting date, broadcast N fertilization, and reduced stubble height) and improved (variable seed rates and plant spacing, delayed planting, banded N fertilization, and increased stubble height). Crop residue and grain yield were greater with CW an...
Efforts have increased to measure nitrate losses from farmland under different management practic... more Efforts have increased to measure nitrate losses from farmland under different management practices due to environmental and public concerns over levels of nitratenitrogen (NO 3-N) in surface and ground waters. This study evaluated the effect of conventional tillage (CT) and strip tillage (ST) practices and three N application rates on NO 3-N concentrations in soil water at a 76 cm depth under irrigated sugarbeet (Beta vulgaris L.) in a clay loam soil. Nitrogen rates were applied as dry urea at
Efforts have increased to measure nitrate losses from farmland under different management practic... more Efforts have increased to measure nitrate losses from farmland under different management practices due to environmental and public concerns over levels of nitrate-nitrogen (NO 3-N) in surface and ground waters. This study evaluated the effect of conventional tillage (CT) and strip tillage (ST) practices and three N application rates on NO 3-N concentrations in soil water at a 76 cm depth under irrigated sugar-beet (Beta vulgaris L.) in a clay loam soil. Nitrogen rates were applied as dry urea at 120, 150, 180 kg N ha −1 in 2006; 130, 160, 190 kg N ha −1 in 2007; and 110, 140, 170 kg N ha −1 in 2008. Soil water volumes were measured weekly during each growing season using three ceramic suction cup samplers per plot placed at a 76 cm depth below the soil surface under each tillage. Results indicated that NO 3-N concentrations at the 76 cm depth in the soil profile were not significantly affected by either tillage practice or by N application rate due to soil variability across the fi...
Determining seed quality parameters is an integral part of cultivar improvement and germplasm scr... more Determining seed quality parameters is an integral part of cultivar improvement and germplasm screening. However, quality tests are often time consuming, seed destructive, and can require large seed samples. This study describes the development of near-infrared spectroscopy (NIRS) calibrations to measure moisture, oil, fatty acid profile, nitrogen, glucosinolate, and chlorophyll content in six species from the Brassicaceae family. Rapeseed and similar oilseeds are potential feedstocks for producing hydrotreated renewable jet fuel. Screening samples with NIRS would allow cultivars with desirable characteristics to be quickly identified. A total of 367 samples of six species (Brassica napus, Brassica carinata, Brassica juncea, Brassica rapa, Sinapis alba, and Camelina sativa) were scanned with NIRS. Global calibrations for all six species were developed using modified partial least squares regression with reference values obtained through wet chemistry techniques. Comparing predicted values to reference data, the coefficients of determination (r 2) and ratios of performance to deviation (RPD) varied, with some calibrations performing better than others. The calibration equations for seed oil content (r 2 =0.98, RPD=7.3) and nitrogen (r 2 =0.98, RPD=5.3) performed very well while the equations for seed moisture (r 2 =0.93, RPD=3.8) and total glucosinolate content (r 2 =0.92, RPD=2.3) were more qualitative. Large variation was observed for chlorophyll content (0-390 mg/kg) so two calibration equations were developed, one for the higher and one for the lower range of values. When combined, these calibrations also showed very good performance (r 2 =0.99, RPD=14). The performance of the calibrations for the fatty acids was more varied, with some performing very well, such as the calibration for C 18:3 (r 2 =0.99, RPD=9.9), and others, such as C 22:0 (r 2 =0.69, RPD=1.9), showing poor correlation.
Hydrotreated renewable jet fuel (HRJ) derived from crop oils has been commercially demonstrated, ... more Hydrotreated renewable jet fuel (HRJ) derived from crop oils has been commercially demonstrated, but full-scale production has been hindered by feedstock costs that make it more costly than petroleumbased fuels. Maintaining low feedstock costs while developing crops attractive to growers will be key to producing affordable HRJ and creating a dependable supply. Several Brassica oilseed species could potentially serve as feedstock, but genotypes agronomically and economically well suited for a given region will likely vary with environment and current cropping systems. The objectives of this study were to evaluate seed and seed oil yields of 12 summer annual Brassica genotypes representing six different species [Brassica napus L., Brassica rapa L., Brassica juncea L., Brassica carinata L., Sinapis alba L., and Camelina sativa (L.) Crantz.] and identify environmental factors that might limit their growth and oil production. The study was conducted during 2013 and 2014 in west central Minnesota, U.S. on a Barnes loam soil. This study is part of a larger project focused on evaluating the same set of oilseeds across the major wheat (Triticum aestivum L.) growing areas of the U.S. Seed yields for the 12 springsown crops in Minnesota ranged from 1058 to 3718 kg ha −1 in 2013 and 515 to 2020 kg ha −1 in 2014. The range in seed oil yield was 287-1588 kg ha −1 in 2013 and 210-885 kg ha −1 in 2014. Plant lodging was a serious issue in 2013, but it varied widely among genotypes. In 2014, which was characterized by an abnormally wet spring, disease infection {most likely white leaf spot [Pseudocercosporella capsellae (Ellis & Everh.) Deighton 1973]} and flea beetle [Phyllotreta cruciferae (Goeze)] feeding led to plant damage, but these were primarily confined to certain Brassica napus cultivars. In west central Minnesota, certain B. napus canola lines and B. carinata produced the greatest seed and oil yields. B. carinata was the latest maturing species in the study, produced the highest biomass, and tended to have low harvest indices, indicating ample room for yield improvement. For any given ecoregion, striking a balance among crop yield, agricultural input costs, and optimum species/cultivar choice for a particular cropping system will be important for providing a reliable and affordable feedstock for HRJ. Published by Elsevier B.V. ଝ Mention of trade names or commercial products in this publication is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the U.S. Department of Agriculture. USDA is an equal opportunity provider and employer.
Crucifer oilseeds as renewable biofuels feedstock could offset demand for petroleum-based alterna... more Crucifer oilseeds as renewable biofuels feedstock could offset demand for petroleum-based alternatives. Current knowledge is limited regarding crop yield potential and N management in semi-arid cropping systems. In NE Montana, a 5-yr study considered no-till production of durum (Triticum durum Desf.) in rotation with oilseed crucifers camelina [Camelina sativa (L.) Crantz], crambe (Crambe abyssinica Hochst. ex R.E. Fries), and Brassica juncea L. canola, with durum-chemical fallow as the control. The N use efficiency was significantly related to seed yield in the three crucifer oilseeds and that juncea canola typically utilized N more efficiently than crambe and camelina. Similarly, N use efficiency was significantly related to grain yield in durum following oilseeds. Yield of durum following juncea canola was as great as that for durum following fallow and greater than that for durum following camelina or crambe. Durum following camelina, juncea canola, or fallow used N more efficie...
Lack of diversification constrains dryland spring wheat (Triticum aestivum L.) production in the ... more Lack of diversification constrains dryland spring wheat (Triticum aestivum L.) production in the northern Great Plains. We initiated a field study in 2004 comparing four crop rotations with each component present in a two-by-two matrix of tillage (conventional vs. zero tillage) and management (conventional vs. ecological) systems. Rotations were continuous spring wheat (SW), SW-pea, SW-barley hay-pea, and SW-barley hay-corn-pea. Ecological management practices varied by crop and were designed to improve snow capture and competitiveness with weeds. Tillage system rarely influenced SW production. Conversely, rotation and management system interacted with years. Over six years, SW in diversified rotations typically had greater soil water content at planting, resulting in greater water use and 473 kg ha-1 additional grain yield than continuous SW. Conversely, ecologically managed SW averaged 644 kg ha-1 less yield than conventionally managed SW. Diversified rotations improved SW yield u...
Diversification of continuous durum system can improve economic and environmental sustainability ... more Diversification of continuous durum system can improve economic and environmental sustainability in semiarid cropping systems, but little is known about the influence of rotation type and management system on durum performance. We conducted a study from 2005 to 2011 comparing two sets of crops in stacked (durum-durum-canola-pea and durum-durum-flax-pea) and alternate-year (durum-canola-durum-pea and durum-flax-durum-pea) rotations under conventional and ecological management levels on durum yield and characteristics. Continuous durum was included as a control. Conventional management included preplant tillage, broadcast urea, standard seeding rates, and short durum residue height. Ecological management included zero tillage, banded urea at planting, greater seeding rates, and tall durum residue height. Average durum grain yield, plant height, and plant stand across years were lower in durum-durum-canola-pea than other rotations under the conventional but not under the ecological man...
<p>Renewable bioenergy feedstocks offset the demand for conventional petrol... more <p>Renewable bioenergy feedstocks offset the demand for conventional petroleum-based energy resources. Switchgrass (Panicum virgatum L.) is a warm-season perennial C4 grass that has been utilized for lingo-cellulosic ethanol production and direct energy via combustion. However, little is known about its potential as a feedstock in the semi-arid northern Great Plains USA, including the impact of N fertilizer application on biomass production and on environmental quality. A field study initiated in 2009 seeded ‘Sunburst’ switchgrass into 12.2 m by 30.5 m plots. Split plots randomized within each main plot included fertilizer N broadcast each spring at 0, 28, 56, and 84 kg N per ha as urea, with four treatment replicates. Aboveground biomass, allowing a 20 cm stubble height, was harvested, weighed, and dried at 55 deg C each fall beginning in 2011 from four randomly selected 0.25 m sq areas. Soil cores were taken to a depth of 1.2 m in fall 2018, air-dried, and analyzed for soil nitrate. Switchgrass biomass ranged from 1.8 to 12.3 Mg per ha. In most years, N application increased switchgrass biomass, but response to N rates above 28 kg per ha was inconsistent. Biomass from fertilized switchgrass averaged 6.5 Mg per ha compared to 4.4 Mg per ha for the unfertilized control.  Soil nitrate levels indicated the potential of (over)fertilization of switchgrass feedstocks to impact water resources in semi-arid environments.</p>
Roots help in soil water and nutrient uptake and provide carbon (C) input for soil C sequestratio... more Roots help in soil water and nutrient uptake and provide carbon (C) input for soil C sequestration, but information on root biomass of bioenergy perennial grasses is lacking. Root/shoot ratios are used to estimate crop root biomass and C inputs, but the values for perennial grasses are also scanty. We examined root biomass, root/shoot ratios, and soil water contents to a depth of 120 cm after grass harvest in the fall for three bioenergy perennial grasses applied with four nitrogen (N) fertilization rates from 2011 to 2013 in the northern Great Plains, USA. Perennial grasses were intermediate wheatgrass (Thinopyrum intermedium [Host] Barkworth and Dewey), smooth bromegrass (Bromus inermis L.), and switchgrass (Panicum virgatum L.), and N fertilization rates were 0, 28, 56, and 84 kg N ha−1. Root biomass declined with depth and about 60% of the total biomass was located at 0-15 cm where intermediate wheatgrass and switchgrass had higher biomass than smooth bromegrass in 2011. Shoot biomass was greater in intermediate wheatgrass in 2011 and in switchgrass in 2013 than other grasses and increased with increased N rates. Root/shoot ratio was greater in switchgrass than other grasses at 0-120 cm in 2011, but was greater in smooth bromegrass than switchgrass at 0-60, 0-90, and 0-120 cm in 2012 and 2013. Mean root/shoot ratios across N rates and years were not different among grasses and varied from 1.54 at 0-15 cm to 2.54 at 0-120 cm, which were substantially greater than 0.15 and 0.33, respectively, observed for spring wheat (Triticum aestivum L.). Soil water content increased with depth and was greater under switchgrass than other grasses at 0-120 cm in 2011 and 2013. Water content varied with N rate at various soil depths and years. Root biomass was negatively correlated with soil water content (r = −0.56, P = 0.03, n = 15). Because of greater root and shoot biomass, intermediate wheatgrass reduced soil water content due to increased water uptake and will likely provide more C inputs for soil C sequestration from belowground biomass compared to smooth bromegrass and spring wheat.
Nitrogen balance provides a measure of agroecosystem performance and environmental sustainability... more Nitrogen balance provides a measure of agroecosystem performance and environmental sustainability by taking into accounts of N inputs and outputs and N retention in the soil. The objective of this study was to evaluate N balance based on N inputs and outputs and soil N sequestration after 7 yr in response to five dryland crop rotations (two 4-yr stacked and two 4-yr alternate-year rotations and one monocropping) and two cultural practices arranged in a split-plot design in the northern Great Plains, USA. Stacked rotations were durum (Triticum turgidum L.)-durum-canola (Brassica napus L.)-pea (Pisum sativum L.) (D-D-C-P) and durum-durum-flax (Linum usitatissimum L.)-pea (D-D-F-P). Alternate-year rotations were durum-canola-durum-pea (D-C-D-P) and durum-flax-durum-pea (D-F-D-P). Monocroppping was continuous durum (CD). Cultural practices were traditional (conventional till, recommended seed rate, broadcast N fertilization, and reduced stubble height) and ecological (no-till, increased seed rate, banded N fertilization, and increased stubble height). Total annual N input due to N fertilization, pea N fixation, atmospheric N deposition, crop seed N, and nonsymbiotic N fixation was lower in CD than other crop rotations, regardless of cultural practices. Total N output due to crop grain N removal and N losses due to denitrification, volatilization, plant senescence, N leaching, gaseous N (NO x) emissions, and surface runoff was lower in traditional CD and D-F-D-P than traditional D-C-D-P and ecological D-C-D-P, D-D-C-P, and D-F-D-P. Nitrogen sequestration rate at 0-125 cm from 2005 to 2011 ranged from 40 kg N ha À1 yr À1 for ecological D-D-F-P to 52 kg N ha À1 yr À1 for ecological CD. Nitrogen balance ranged from À39 to À36 kg N ha À1 yr À1 with CD compared to 9-25 kg N ha À1 yr À1 with other crop rotations in both cultural practices. Because of reduced reliance on external N inputs and increased grain N removal, N flow, and N surplus, crop rotations with legumes, nonlegumes, and oilseed crops in the rotation can be productive and environmentally sustainable compared with monocropping, regardless of cultural practices.
All rights reserved. No part of this periodical may be reproduced or transmitted in any form or b... more All rights reserved. No part of this periodical may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher.
The Great Plains region of the United States is an area of widespread dryland crop production, wi... more The Great Plains region of the United States is an area of widespread dryland crop production, with wheat being the dominant crop. Precipitation in the region ranges from 300 to 500 mm annually, with the majority of precipitation falling during hot summer months. The prevailing cropping system is a two-year rotation of wheat and summer fallow. The adoption of no-till practices has resulted in greater precipitation storage and use efficiency, which has led to greater cropping intensity, higher productivity, more diverse crop rotations, and improvements in soil properties. In Colorado, for example, a no-till rotation of winter wheat-maize-fallow increased total annualized grain yield by 75% compared to winter wheat-summer fallow. Soil erosion was reduced to just 25% of that from a conventional tillage wheat-summer fallow system. The primary challenge with reducing fallow frequency is the increase in yield variability and risk of crop failure. Improved approaches for choosing crop or fallow are being developed based on soil water content and forecasted weather. Development of alternative crops, crop rotations, and integrated livestock systems that are sustainable from both economic and ecological perspectives is an ongoing effort. Other research is addressing adaptation of cropping practices to climate change and the potential for dryland biomass crop production for the developing biofuel industry.
Brassicaceae oilseed crops can provide rotation benefits to dryland wheat (Triticum aestivum L.) ... more Brassicaceae oilseed crops can provide rotation benefits to dryland wheat (Triticum aestivum L.) and supply feedstock for biofuel production. However, growers face decisions about what oilseed crop is best suited for an environment. The objective of this study was to determine how varying production environments affect the agronomic performance of modern cultivars of six Brassicaceae crop species and identify ideal genotypes for seven growing environments spanning four ecoregions. A field experiment was replicated in Colorado,
Available water and N fertility are primary constraints to crop production in the northern Great ... more Available water and N fertility are primary constraints to crop production in the northern Great Plains of the USA. A field trial was initiated in 2004 to compare four crop rotations in a complete factorial of two tillage and two management systems. Rotations were continuous spring wheat (SW), pea-SW, barley hay-pea-SW, and barley hay-corn-pea-SW. Tillage systems were no till and field cultivator tillage, while management systems were conventional and ecological. Conventional management included broadcast nitrogen fertilizer, standard seeding rates, and short stubble height. Ecological management practices varied by crop, and included banded nitrogen fertilizer for cereals, increased seeding rate, delayed planting date for SW, and taller stubble height. Continuous SW grain yield was 26% lower than SW in more diverse rotations. Pea grain yield was 18% lower in 2-yr rotations than in more diverse rotations. Ecologically managed SW yielded 29% less than conventionally managed SW, presu...
The quality of this reproduction is dependent upon the quality of the copy submitted. Broken or i... more The quality of this reproduction is dependent upon the quality of the copy submitted. Broken or indistinct print, colored or poor quality illustrations and photographs, print bleed-through, substandard margins, and improper alignment can adversely affect reproduction. In the unlikely event that the author did not send a complete manuscript and there are missing pages, these will be noted. Also, if unauthorized copyright material had to be removed, a note will indicate the deletion.
<p>... more <p>Better management practices have been used to increase soil water storage and reduce evaporation from the soil surface to optimize crop water use efficiency (WUE) in irrigated agriculture. A field study was conducted to evaluate the effect of  conventional tillage (CT), No-till (NT) and strip tillage (ST) practices on yield, water use (WU) and WUE of sugarbeet (Beta vulgaris L.) on a clay loam soil under over-head sprinkler irrigation system in the northern Great Plains. Tillage treatments were replicated five times in a randomized block design. Seasonal WU and WUE for sugarbeet root and sucrose yield were determined for the 2018 and 2019 growing seasons according to the water balance and WUE equations under three tillage practices. Results showed that no significant differences due to tillage treatment were found for crop WU, root yield, sucrose yield, and WUE for sugarbeet root and sucrose in 2018 and 2019 growing seasons. In 2019, the average value of WU across three tillage systems (616 mm) was significantly greater relative to 2018 (468 mm) due to atypical large rainfalls (218mm) occurred in September of 2019. Consequently, WUE values for both root and sucrose yield in 2019 under CT, NT, and ST were significantly greater than those in 2018. While NT and ST practices are promising alternative to CT for agricultural production in this region, further research is needed prior to making any recommendation.</p>
Information on the long-term effect of management practices on soil C and N stocks is lacking. An... more Information on the long-term effect of management practices on soil C and N stocks is lacking. An experiment was conducted from 2004 to 2011 in the northern Great Plains, USA to examine the effects of tillage, crop rotation, and cultural practice on annualized crop residue (stems + leaves) returned to the soil and grain yield, and soil total C (STC) and total N (STN) stocks at the 0-120 cm depth. Tillage practices were no-tillage (NT) and conventional tillage (CT) and crop rotations were continuous spring wheat ( L.) (CW), spring wheat-pea ( L.) (W-P), spring wheat-barley ( L.) hay-pea (W-B-P), and spring wheat-barley hay-corn ( L.)-pea (W-B-C-P). Cultural practices were traditional (conventional seed rates and plant spacing, conventional planting date, broadcast N fertilization, and reduced stubble height) and improved (variable seed rates and plant spacing, delayed planting, banded N fertilization, and increased stubble height). Crop residue and grain yield were greater with CW an...
Efforts have increased to measure nitrate losses from farmland under different management practic... more Efforts have increased to measure nitrate losses from farmland under different management practices due to environmental and public concerns over levels of nitratenitrogen (NO 3-N) in surface and ground waters. This study evaluated the effect of conventional tillage (CT) and strip tillage (ST) practices and three N application rates on NO 3-N concentrations in soil water at a 76 cm depth under irrigated sugarbeet (Beta vulgaris L.) in a clay loam soil. Nitrogen rates were applied as dry urea at
Efforts have increased to measure nitrate losses from farmland under different management practic... more Efforts have increased to measure nitrate losses from farmland under different management practices due to environmental and public concerns over levels of nitrate-nitrogen (NO 3-N) in surface and ground waters. This study evaluated the effect of conventional tillage (CT) and strip tillage (ST) practices and three N application rates on NO 3-N concentrations in soil water at a 76 cm depth under irrigated sugar-beet (Beta vulgaris L.) in a clay loam soil. Nitrogen rates were applied as dry urea at 120, 150, 180 kg N ha −1 in 2006; 130, 160, 190 kg N ha −1 in 2007; and 110, 140, 170 kg N ha −1 in 2008. Soil water volumes were measured weekly during each growing season using three ceramic suction cup samplers per plot placed at a 76 cm depth below the soil surface under each tillage. Results indicated that NO 3-N concentrations at the 76 cm depth in the soil profile were not significantly affected by either tillage practice or by N application rate due to soil variability across the fi...
Determining seed quality parameters is an integral part of cultivar improvement and germplasm scr... more Determining seed quality parameters is an integral part of cultivar improvement and germplasm screening. However, quality tests are often time consuming, seed destructive, and can require large seed samples. This study describes the development of near-infrared spectroscopy (NIRS) calibrations to measure moisture, oil, fatty acid profile, nitrogen, glucosinolate, and chlorophyll content in six species from the Brassicaceae family. Rapeseed and similar oilseeds are potential feedstocks for producing hydrotreated renewable jet fuel. Screening samples with NIRS would allow cultivars with desirable characteristics to be quickly identified. A total of 367 samples of six species (Brassica napus, Brassica carinata, Brassica juncea, Brassica rapa, Sinapis alba, and Camelina sativa) were scanned with NIRS. Global calibrations for all six species were developed using modified partial least squares regression with reference values obtained through wet chemistry techniques. Comparing predicted values to reference data, the coefficients of determination (r 2) and ratios of performance to deviation (RPD) varied, with some calibrations performing better than others. The calibration equations for seed oil content (r 2 =0.98, RPD=7.3) and nitrogen (r 2 =0.98, RPD=5.3) performed very well while the equations for seed moisture (r 2 =0.93, RPD=3.8) and total glucosinolate content (r 2 =0.92, RPD=2.3) were more qualitative. Large variation was observed for chlorophyll content (0-390 mg/kg) so two calibration equations were developed, one for the higher and one for the lower range of values. When combined, these calibrations also showed very good performance (r 2 =0.99, RPD=14). The performance of the calibrations for the fatty acids was more varied, with some performing very well, such as the calibration for C 18:3 (r 2 =0.99, RPD=9.9), and others, such as C 22:0 (r 2 =0.69, RPD=1.9), showing poor correlation.
Hydrotreated renewable jet fuel (HRJ) derived from crop oils has been commercially demonstrated, ... more Hydrotreated renewable jet fuel (HRJ) derived from crop oils has been commercially demonstrated, but full-scale production has been hindered by feedstock costs that make it more costly than petroleumbased fuels. Maintaining low feedstock costs while developing crops attractive to growers will be key to producing affordable HRJ and creating a dependable supply. Several Brassica oilseed species could potentially serve as feedstock, but genotypes agronomically and economically well suited for a given region will likely vary with environment and current cropping systems. The objectives of this study were to evaluate seed and seed oil yields of 12 summer annual Brassica genotypes representing six different species [Brassica napus L., Brassica rapa L., Brassica juncea L., Brassica carinata L., Sinapis alba L., and Camelina sativa (L.) Crantz.] and identify environmental factors that might limit their growth and oil production. The study was conducted during 2013 and 2014 in west central Minnesota, U.S. on a Barnes loam soil. This study is part of a larger project focused on evaluating the same set of oilseeds across the major wheat (Triticum aestivum L.) growing areas of the U.S. Seed yields for the 12 springsown crops in Minnesota ranged from 1058 to 3718 kg ha −1 in 2013 and 515 to 2020 kg ha −1 in 2014. The range in seed oil yield was 287-1588 kg ha −1 in 2013 and 210-885 kg ha −1 in 2014. Plant lodging was a serious issue in 2013, but it varied widely among genotypes. In 2014, which was characterized by an abnormally wet spring, disease infection {most likely white leaf spot [Pseudocercosporella capsellae (Ellis & Everh.) Deighton 1973]} and flea beetle [Phyllotreta cruciferae (Goeze)] feeding led to plant damage, but these were primarily confined to certain Brassica napus cultivars. In west central Minnesota, certain B. napus canola lines and B. carinata produced the greatest seed and oil yields. B. carinata was the latest maturing species in the study, produced the highest biomass, and tended to have low harvest indices, indicating ample room for yield improvement. For any given ecoregion, striking a balance among crop yield, agricultural input costs, and optimum species/cultivar choice for a particular cropping system will be important for providing a reliable and affordable feedstock for HRJ. Published by Elsevier B.V. ଝ Mention of trade names or commercial products in this publication is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the U.S. Department of Agriculture. USDA is an equal opportunity provider and employer.
Crucifer oilseeds as renewable biofuels feedstock could offset demand for petroleum-based alterna... more Crucifer oilseeds as renewable biofuels feedstock could offset demand for petroleum-based alternatives. Current knowledge is limited regarding crop yield potential and N management in semi-arid cropping systems. In NE Montana, a 5-yr study considered no-till production of durum (Triticum durum Desf.) in rotation with oilseed crucifers camelina [Camelina sativa (L.) Crantz], crambe (Crambe abyssinica Hochst. ex R.E. Fries), and Brassica juncea L. canola, with durum-chemical fallow as the control. The N use efficiency was significantly related to seed yield in the three crucifer oilseeds and that juncea canola typically utilized N more efficiently than crambe and camelina. Similarly, N use efficiency was significantly related to grain yield in durum following oilseeds. Yield of durum following juncea canola was as great as that for durum following fallow and greater than that for durum following camelina or crambe. Durum following camelina, juncea canola, or fallow used N more efficie...
Lack of diversification constrains dryland spring wheat (Triticum aestivum L.) production in the ... more Lack of diversification constrains dryland spring wheat (Triticum aestivum L.) production in the northern Great Plains. We initiated a field study in 2004 comparing four crop rotations with each component present in a two-by-two matrix of tillage (conventional vs. zero tillage) and management (conventional vs. ecological) systems. Rotations were continuous spring wheat (SW), SW-pea, SW-barley hay-pea, and SW-barley hay-corn-pea. Ecological management practices varied by crop and were designed to improve snow capture and competitiveness with weeds. Tillage system rarely influenced SW production. Conversely, rotation and management system interacted with years. Over six years, SW in diversified rotations typically had greater soil water content at planting, resulting in greater water use and 473 kg ha-1 additional grain yield than continuous SW. Conversely, ecologically managed SW averaged 644 kg ha-1 less yield than conventionally managed SW. Diversified rotations improved SW yield u...
Diversification of continuous durum system can improve economic and environmental sustainability ... more Diversification of continuous durum system can improve economic and environmental sustainability in semiarid cropping systems, but little is known about the influence of rotation type and management system on durum performance. We conducted a study from 2005 to 2011 comparing two sets of crops in stacked (durum-durum-canola-pea and durum-durum-flax-pea) and alternate-year (durum-canola-durum-pea and durum-flax-durum-pea) rotations under conventional and ecological management levels on durum yield and characteristics. Continuous durum was included as a control. Conventional management included preplant tillage, broadcast urea, standard seeding rates, and short durum residue height. Ecological management included zero tillage, banded urea at planting, greater seeding rates, and tall durum residue height. Average durum grain yield, plant height, and plant stand across years were lower in durum-durum-canola-pea than other rotations under the conventional but not under the ecological man...
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