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Department of Agronomy

Department of Agronomy
Kansas State University
2004 Throckmorton PSC
1712 Claflin Road
Manhattan, KS 66506-0110

Ph: +1-785-532-6101
Fx: +1-785-532-6094

Kraig Roozeboom's Research Projects

Cropping Systems

Long-term Yield Responses to Crop Rotation and Tillage in Northeast Kansas

Contributors: Dallas Peterson, Kraig Roozeboom

An experiment examining two-year crop rotations and three tillage systems was initiated near Manhattan, Kansas in 1974. The study includes soybean (SB), grain sorghum (GS), and wheat (WT) in continuous various two-year sequences: SB/SB, SB/WT, SB/GS, GS/GS, GS/SB, WT/WT, WT/SB. All crop rotations contain three tillage systems: conventional tillage (CT), reduced tillage (RT), and no-tillage (NT). The 2007 growing season represents the 33rd consecutive year of data collection from this study, providing an excellent opportunity to summarize and examine the long-term effects of crop rotation and tillage and how they interact. For soybean, no-till has resulted in the greatest yield on average, but the largest response to no-till has occurred when soybean was rotated with sorghum. The greatest soybean yield has occurred in rotation with wheat, but rotation with sorghum also has increased yield compared to continuous soybean. Grain sorghum has responded in a similar manner with greatest yields in no-till rotation with soybean. Grain sorghum yields have decreased slightly with no-till in a continuous grain sorghum rotation. Decreased yields in continuous no-till sorghum are likely because of fall panicum infestations. Wheat yields are least in continuous no-till wheat, probably due to downy brome infestations and planting difficulties. Wheat yields are greatest in a soybean-wheat rotation. More than 30 years of experimental results indicate that crop rotation provides yield benefits and is essential with no-till. In general, no-till crops grown in rotation provided the greatest yields over the entire period. The benefits of no-till for crop yields were most pronounced in dry years.

Insert link to file: Long-term Yield Response to Rotation and Tillage ASA Poster.pdf

Corn and Grain Sorghum Comparison: All Things Considered

Contributors: Yared Assefa, Kraig Roozeboom, Curtis Thompson, Alan Schlegel, Loyd Stone, Jane Lingenfelser

Corn and grain sorghum (Sorghum bicolor subsp. bicolor L) are among the top cereal crops world wide, and both are key for global food security. Similarities between the two crops, particularly their adaptation for warm-season grain production, pose an opportunity for comparisons to inform appropriate cropping decisions. This book provides a comprehensive review of the similarities and differences between corn and grain sorghum. It compares corn and sorghum crops in areas such as morphology, physiology, phenology, yield, resource use and efficiency, and impact of both crops in different cropping systems.

Additional Information

Sesame for Kansas Cropping Systems

Contributors: Kraig Roozeboom, Curtis Thompson

Sesame is an oil seed crop that is well adapted to the high-temperatures typical of summers in the central Great Plains. A series of experiments has demonstrated that sesame can be grown successfully in Kansas with minimal seed and fertilizer inputs. Depending on commodity prices, sesame returns can be very competitive with soybeans in areas where soybean yields are likely to be less than 30 bushels per acre.

Insert link to file: 2011 Sesame Summary.pdf

Biofuel Cropping Systems

Long-term rotations and crop alternatives

Contributors: John Propheter, Scott Staggenborg, Lucas Haag, Jason Waite, Andrew McGowan, Kraig Roozeboom

A long-term rotation of several bioenergy crop alternatives was established in 2007. The objective of the study is to directly compare potential bioenergy feedstock crops in the context of an ongoing cropping system. Comparisons include traditional corn based systems, several types of sorghum (e.g. photoperiod sensitive, sweet, grain, brown midrib), as well as perennial grass crops (switch grass, miscanthus). Initial results indicated that annual crops outperformed perennial crops, however, the perennial species were still in the establishment phase. Although rotated corn possessed the greatest potential for starch-based ethanol conversion processes, sweet sorghum has the potential to produce greater total ethanol assuming both biomass and juice can be used as feedstocks for the conversion process.

Insert links to files: aj-102-2-798.pdf, aj-102-2-806.pdf

Sorghum Biomass Genomics and Phenomics

Contributors: Jianming Yu, Donghai Wang, Kraig Roozeboom

As part of a large, multi-state project, 300 biomass sorghum accessions were evaluated at Manhattan Kansas for a number of traits in 2013. Plant height ranged from 4.1 feet to 17.2 feet and lodging scores ranged from 2.5% to 100%. Dry matter yield estimates were as high as 19.1 tons of dry matter per acre.

Cover Crops

Comparison of Cover Crops in Kansas and their effect on Subsequent Grain Sorghum Performance

Contributors: Kevin Arnet, M.S. 2010, Kraig Roozeboom, Johnathan Holman, DeAnn Presley

Cover crops comparison

With the increased cost of fertilizer and herbicide, interest has grown regarding management options that reduce input costs while maintaining cropping system productivity. Intensifying cropping systems with the addition of cover crops has been promoted as a method of reducing weed populations while reducing nitrogen fertilizer requirements and maintaining overall system productivity. Due to variable precipitation patterns and year-to-year variability in amount of precipitation across the state of Kansas, cover crop productivity and their effect on a following grain crop can vary. A study evaluating cover crops in different Kansas environments was conducted to compare the productivity of several different cover crops and their subsequent effects on grain sorghum (Sorghum bicolor) performance. A selection of legume and non-legume species was evaluated for biomass production, nitrogen concentration, and nitrogen accumulation. Eight summer-grown and eight fall-grown cover crops were planted into no-till winter wheat stubble at Manhattan, KS in 2008 and 2009 and Hutchinson, KS in 2009. In all locations, summer-grown crop treatments produced the greatest aboveground biomass and nitrogen accumulation. Within the summer-grown treatments, annual grass species produced the greatest amounts of biomass (≥3392 kg ha-1) and legume species accumulated the greatest amounts of nitrogen, averaging 43 kg ha-1. On average, grain sorghum yields were 867 kg ha-1 greater following a summer-grown cover crop compared to sorghum planted after a fall-grown cover crop. Cover crop treatments that resulted in greater grain sorghum yield also resulted in sorghum that displayed greater normalized difference vegetation index (NDVI) values, greater flag leaf nitrogen concentration, and reached half bloom sooner than sorghum after treatments resulting in low grain sorghum yields. Strong correlations were observed between grain sorghum yield, NDVI value, flag leaf nitrogen concentration, and days after planting until half bloom. These results indicated that cover crops had a significant effect on grain sorghum performance, with greatest performance seen following warm-season legume cover crops.

Provide link to file: Screening Cover Crop Species.pdf

Winter Cover Crop Alternatives for Winter Fallow Systems

Contributors: Oliver Freeman, Ph.D. 2014; Mary Beth Kirkham, Alan Schlegel, Jason Bergtold, Kraig Roozeboom

This study compared legume and non-legume winter cover crops grown for three years (2010-2012) at two locations in Kansas: Manhattan in the northeastern part of the state and in Hutchinson, in the south central part of the state. Six cover crops were studied, three legumes: alfalfa (Medicago sativa L.), Austrian winter pea (Pisum sativum var. arvense Poir.), and red clover (Trifolium pratense L.), and three non-legumes: triticale (X Triticosecale; Triticum x Secale), winter oats (Avena sativa L.), and winter wheat (Triticum aestivum L.). The cover crops were planted at times corresponding to when they might be used in a corn (Zea mays L.) and forage sorghum [Sorghum bicolor (L.) Moench] rotation. However, they were not in rotation with these crops, but the cover crops were planted at times to match corn and forage sorghum harvest times and sampled at times to match corn and forage sorghum planting times in the following year. Each cover crop was sampled for dry matter, and nitrogen and carbon content in the plants was determined to estimate cover crop carbon-to-nitrogen ratio (C:N), nitrogen uptake, and plant-available nitrogen from cover crops. Results indicated that cover crops grown for forage sorghum production systems performed better, which was probably due to the fact that cover crops for this system had additional time to accumulate additional dry matter because forage sorghum is planted later than corn. Triticale produced the greatest amount of dry matter (an average of 4690 kg ha-1 for the three years). It also had the greatest nitrogen uptake (80 kg ha-1). Winter oats were second in dry matter production and averaged 3236 kg ha-1 over the three years. Cover crop C:N was 12:1 on average with triticale grown for the corn production system, which was the lowest ratio observed.. This low C:N ratio indicates that nitrogen would be cycled more rapidly with triticale than with the other cover crops. The legumes often winterkilled, both in Manhattan and Hutchinson. This study indicated that non-legume winter cover crops are better adapted to Kansas than legume winter cover crops.

Winter Cover Crops in Corn and Forage Sorghum Rotations in the Great Plains

Contributors: Oliver Freeman, Ph.D. 2014; Mary Beth Kirkham, Alan Schlegel, Jason Bergtold, Kraig Roozeboom

Winter cover crops have a potential application in systems that harvest summer crops for biofuel. When a crop is harvested for bioenergy, the residue is removed leaving the soil prone to erosion during the winter. It is possible that the use of winter cover crops may allow for more residue to be removed from a field while keeping the soil from blowing. Therefore, the objective of this research was to determine the effect of two winter cover crops on the growth of two biofuel crops, corn (Zea mays L.) and forage sorghum [Sorghum bicolor (L.) Moench] in a corn-forage sorghum rotation. The two cover crops were a legume, Austrian winter pea (Pisum sativum var. arvense Poir.) and winter wheat (Triticum aestivum L.). Control plots were fallowed. The experiment was done for two years at two locations: under rain-fed conditions in Manhattan in the northeastern part of Kansas, where the soil was a Belvue silt loam (coarse-silty, mixed superactive non-acid, mesic Typic Udifuvents) and under irrigated conditions in Tribune in the western part of Kansas, where the soil was a Richfield silt loam (fine, smectitic, mesic Aridic Argiustolls). Two levels of nitrogen were added to the soil: 0 and 101 kg ha-1 N. Grain and stover yields of the corn and forage sorghum were determined at harvest of the crops in the fall, and dry matter of the cover crops was determined at their harvest in the spring. Cover crops had no effect on grain or stover yields of corn or sorghum at either location. At Manhattan, addition of nitrogen fertilizer increased grain yields, but nitrogen had no effect on grain yield at Tribune, probably because the soil at Tribune had more residual nitrogen in it than the soil at Manhattan. During one of the two winters of the study, Austrian winter pea winterkilled at Manhattan. Austrian winter pea survived both winters at Tribune, but it produced less dry matter compared to winter wheat. At both locations, the forage sorghum yielded more stover than did the corn. This suggests that, under both rain-fed and irrigated conditions in Kansas, forage sorghum would be more productive for bio-energy production than corn. The results of the study showed that wiunter cover crops can be grown in rotation with forage sorghum and/or corn at Manhattan and with irrigation at Tribune, Kansas with a minimal negative impact on summer crop production.

Suppression of Marestail in Various Cover Crop and Herbicide Systems within Soybean Production

Contributors: Andi Shore, M.S. 2014, Anita Dille, Dallas Peterson, Kraig Roozeboom

With the rise of herbicide resistant weeds, it has become necessary to examine alternative methods of weed control in cropping systems. Combining the use of herbicides with a cover cropping system shows promise in effectively controlling weeds. The objectives of this study are to examine the level of weed suppression obtained by using cover crops and explore the degree of weed suppression that can be achieved through various herbicide treatment timings paired with cover crops and fallow systems. Plots were sown to rye, barley, annual ryegrass, wheat, radish and a rye/radish mixture in November 2012. Previous crops were grain sorghum and soybean, standing stubble was present at planting of cover crops. Spring oats were sown on April 2013. Selected plots were sprayed with Dicamba or a mixture of Dicamba and Valor XLT in November 2012 and April 2013, creating fall sprayed treatments with no residual (FNRES), fall sprayed plots with residual (FRES), spring sprayed plots with no residual (SNRES), and spring sprayed plots with residual (SRES). One treatment combined a rye cover crop with spring residual herbicides (Rye SRES). Cover crops were terminated in late May 2013, using two methods: a tractor pulled roller-crimper and spray applied glyphosate (32 oz/acre). Soybeans (385NRS) were planted in early June 2013. The study was sprayed in late June with RoundUp PowerMax (32 oz/acre) and FirstRate (0.3 oz/acre). The study was harvested in late October 2013. Seed yield, marestail suppression notes, crop and weed biomass were collected on all plots. Cover crop biomass was sampled one week before termination and soybean biomass was collected one month before harvest. Compared to a fallow control, cover crops suppressed marestail biomass accumulation. Of the cover crops, rye had the greatest level of marestail suppression. However, rye with a spring applied residual herbicide and other herbicide treatments tended to more effectively suppress marestail biomass accumulation. All herbicide controlled plots had greater marestail biomass suppression than cover crop systems with the exception of rye with spring applied residual herbicide before and after termination. Cover crops with greater accumulation of biomass tended to more effectively suppress marestail biomass accumulation. Cover crops in sorghum stubble had a greater impact on soybean biomass accumulation than chemical treatments. Overall, termination method in sorghum stubble had a greater impact on soybean biomass accumulation than in soybean stubble, with the exception of spring planted oats.

Insert link to file: Utilizing Cover Crops for Marestail Suppression before Soybeans.pdf

Water Use Comparison of Cover Crop Mixtures and Single Species in Relation to Biomass Production

Contributors: Matti Kiykendall, M.S. 2015, Kraig Roozeboom, Vara Prasad, Gerard Kluitenberg

Cover crops are associated with several potential benefits for cropping systems and are becoming increasingly popular in the Great Plains Region. However, the possibility that they may limit the water available for cash crops can be a major drawback for producers and has led to recurring questions arise about how much water cover crops use. The objective of this study is to quantify changes in soil profile water by a variety of summer planted cover crop species and mixtures.

Insert link to file: Water Use and Biomass Production of Cover Crops.pdf

Cover Crops in No-till Rotations

Contributors: Kevin Arnet, M.S. 2010, Megan Brown, M.S. 2014, Justin Petrosino, M.S. 2010, Kraig Roozeboom, Anita Dille, Peter Tomlinson

A long-term experiment was initiated in 2007 to examine the influence of cover crops in a no-till cropping system including soybeans, wheat, and sorghum. Cover crops are planted during the fallow period between wheat harvest and sorghum planting. Fallow and double-crop soybean treatments are included as two alternatives representing systems that do not employ cover crops. A range of nitrogen rates are applied to the sorghum crop to facilitate quantifying the response of sorghum grain yield to additional nitrogen in all treatments.

Crop yield responses to N rates with and without cover crops already have revealed some interesting patterns. Sorghum planted after some cover crops (legumes and non-legumes with low C:N), has demonstrated greater fertilizer use efficiency at low and intermediate nitrogen application rates in three of the five harvest years. GreenSeeker NDVI data collected from pre-heading sorghum supports the conclusion that nitrogen uptake differs depending on N rate as well as cover crop type. The effect of cover crop species on yields of the soybean and wheat crops in different phases of the rotation has not been consistent.

Preliminary research quantifying season long N2O emissions from the 80 kg ha-1 nitrogen rate and non-legume cover crops suggests that cover crops may play an important role in reducing N2O-N loss from the system. The chemical fallow treatment had significantly higher cumulative nitrous oxide flux (P=0.05; LSD 0.1 = 0.37) compared to both summer and winter non-legume cover crops in the wheat – fallow/cover crop phase of the rotation.

Insert link to file: Cover Crops in Eastern KS No-till Cropping Systems.pdf

Corn Management

Effect of Delayed Planting on Corn in Central Kansas

Contributors: Aaron Sindelar, Kraig Roozeboom, William Heer, Barney Gordon

Interest has grown regarding management options to improve and stabilize dryland corn production (Zea mays L.) in challenging environments. Grain sorghum (Sorghum bicolor L.) has been documented to produce more consistent grain yields than corn in dryland production in Kansas. In periods of reduced water availability, sorghum can delay growth and development, allowing the plant to capture water later in the season for flowering and grainfill. Delaying planting in corn can serve a similar purpose. In central Kansas, planting corn earlier so pollination occurs before periods of extreme stress has been successful, but little research has investigated delayed planting or its long-term effect. The objectives of this study were to evaluate plant growth and yield response to delayed planting through field research and to quantify its long-term effects through crop model simulations. Field trials with delayed planting dates and hybrids of varying maturity revealed that yield at Manhattan, KS, did not decrease significantly until the final planting date in 2007 and did not decrease at all with delayed planting in 2008. At Belleville, yield increased with later planting in 2007 and was not affected by planting date in 2008. At Hutchinson, yield decreased significantly with each planting date until the third in 2007. However, in 2008, yield increased significantly from the second to fourth planting dates. Simulations in CERES-Maize over 51 years revealed no difference in yield between planting dates at Manhattan and Belleville, but showed a significant decrease between the first planting date and the third and fourth planting dates at Hutchinson. Chi-squared tests indicated that all planting date x hybrid combinations at Manhattan and Belleville produced economically profitable yields at frequencies significantly greater than 0.5. At Hutchinson, all but two of the twelve planting date x hybrid combinations produced profitable yields at frequencies significantly less than 0.5. The two remaining combinations produced profitable yields at frequencies that were not different than 0.5. One of these combinations was observed at the fourth planting date. These results suggest that economical viability of delayed planting of corn is heavily dependent on location.

Insert link to file: Corn Response to Delayed Planting in the Central Great Plains AJ-0530.pdf

Foliar Fungicides on Corn

Contributors: Kraig Roozeboom, Stu Duncan, Barney Gordon, Curtis Thompson, David Hallauer, Mike Hanson, Mike Hershey, Larry Maddux, Tom Roberts

A series of studies were conducted to assess the effect of foliar corn fungicides on corn canopy health and grain yield. The likelihood of yield response was greatest in continuous no-till corn in southwest Kansas where the incidence of gray leaf spot was greatest.

Insert link to file: Corn Fungicide Summary.pdf

Flex-Ear and Fixed-Ear Hybrid Response to Plant Population

Contributors: Kraig Roozeboom, Stu Duncan, Lance Visser

Seed companies often characterize hybrids as fixed-ear or flex-ear types. Hybrid descriptions indicate that ears of fixed-ear hybrids do not adjust as readily to environmental conditions, but ears of flex-ear hybrids do. Flex-ear hybrids are often targeted for more difficult growing conditions and are planted with fewer plants per acre compared to a fixed-ear hybrid. The objective of these studies was to determine if hybrids characterized as flex-ear or fixed-ear have different optimum plant densities in different environments. Two hybrids (one characterized as fixed-ear, one characterized as flex-ear) were planted at several locations in Kansas in several different years. At each location, plant density was established by thinning before V5. In only a few instances did response to plant density depend on hybrid type. In most environments, yield response to plant density was similar for both fixed and flex-ear hybrids.

Insert link to file: Flex Fixed Corn Hybrid Response to Population Poster.pdf

Interaction of Planting Date, Hybrid Maturity, and Seeding Rate

Contributors: Kraig Roozeboom, Mark Claassen, Larry Maddux

Early planting is key to successful corn production in drought-prone areas where yields are frequently limited by available soil moisture. Surface residue associated with no-till cropping systems conserves soil moisture but also can slow soil warming in the spring, potentially delaying emergence. Experiments conducted in central and eastern Kansas in 2004 to 2008 tested three hybrids of differing maturities at planting dates ranging from mid-March to mid-April. Each hybrid-by-planting date combination was evaluated at three populations. Corn was no-till planted following a soybean crop in the respective experiments. The objective was to identify optimum combinations of hybrid maturity and populations for early planting dates in no-till, dryland cropping systems on shallow topsoils. Greater plant density usually resulted in greater yields within the range of populations compared in these experiments, regardless of planting date. The positive yield response to increasing populations was larger in environments that supported greater yields. Exceptions occurred if planting was delayed until May or June, when yield decreased with greater plant density, or in a drought situation, when there was no response to plant population. Yield response to planting date varied with year and location but tended to decline slightly with later planting dates on average. The earliest planting dates posed a greater degree of risk from damage to corn by freezing temperatures. Medium- or full-season hybrids produced the greatest yields in almost every planting date – population combination. Early-season hybrids were superior only in drought conditions or if planting was delayed into mid-May or June. Although pushing the planting date as early as possible improved yield in some years, results indicated that with existing weather patterns, the risk of freeze damage is significant and may offset that benefit.

Insert link to file: Early Corn Planting.pdf

Effect of Corn Planting Depth on Emergence Timing and Yield

Contributors: Kraig Roozeboom, Stewart Duncan

Previous research has indicated that corn yields are more dependent on emergence timing and final plant population than stand uniformity. The objective of this study was to examine specifically how corn planting depth affects emergence timing, stand density and yield. Six seeding depths were used, ranging from 1.0 to 3.5 inches. This study had two planting dates in 2011, April 11 and May 3, in Manhattan, KS and two locations with different planting dates in 2012, Manhattan (April 17) and Hiawatha, KS (April 20). Emergence was delayed at all planting depths for the early planting date in 2011, likely due to soil temperatures remaining below 50⁰F for almost three weeks after planting. Later planting dates had more consistent emergence, with planting depth showing no impact on final stand or yield. This research supports current recommendations to plant at depths of 1.5 to 2.5 inches, especially when planting into cooler soils. At later planting dates with warmer soils, planting depth had no impact on final stand or yield.

Insert link to file: KLR Corn Planting Depth.pdf

Sorghum Management

Sorghum Planting Management

Contributors: Kraig Roozeboom, Alassane Maiga, Bill Heer, Randall Nelson, John Holman, Alan Schlegel

A series of experiments conducted by the Kansas State University Department of Agronomy and funded by the Kansas Grain Sorghum Commission examined the interactions between planting date, hybrid maturity, row spacing across a range of production environments. Two hybrids (one medium early and one medium late) were planted at two planting dates (typically early to mid-May and early to mid-June) in two row spacings (10-inch and 30-inch) at four seeding rates (20, 50, 80, and 110 thousand seeds per acre). These experiments were conducted at four locations in central and eastern Kansas over a period of four years. A total of 12 experiments were completed from 2008 through 2011. Three of the four years had growing season precipitation that was at or above normal at most locations. In 2011, precipitation was well below normal for all experiments.

Yield results indicated that the biggest factor to watch when deciding on seeding rate was planting date. Early planting tended to be less responsive to changes in plant population. However, with June planting, plant populations needed to be at or even greater than typical recommendations to maximize yields. Sorghum plants tend not to tiller as readily with warmer temperatures, making adequate stands essential for later plantings. Increasing the population in narrow rows resulted in greater yields in only 1 of the 12 experiments.

Yields in 10-inch rows either equaled or exceeded yields in 30-inch rows in all 12 experiments. This included yield environments that ranged from 50 to 60 bushels per acre at Manhattan in 2011 to yields greater than 150 bushels per acre in 2009 at Belleville. When there was a yield advantage for narrow rows, it added 3 to 25 bushels per acre depending on year and location. The exception to this yield advantage with narrow rows occurred in 2011 at Hutchinson under extreme drought conditions at the highest plant populations. Other experiments have documented yield reductions in narrow rows when drought conditions occur during grain fill. The most common factor affecting yield response to row spacing was planting date, with narrow rows occasionally having a greater advantage with later planting. Although this occurred only twice in the ten experiments with different planting dates in this study, previous work has demonstrated a similar interaction of row spacing with planting date. Narrow rows may compensate in part for the reduced tillering associated with later planting by shortening the time to canopy closure.

One indicator to watch over time is the number of heads per plant. The number of heads per plant decreased as the number of plants per acre increased, tending to level off at close to one head per plant at populations greater than 50,000 plants per acre. In the relatively productive environments of 2008 to 2010, yield was maximized when the sorghum plants produced between 1 and 1.4 heads per plant plant - in other words, when less than half of the plants produced a second productive head. Having too many plants can result in only one head per plant, but can sap water supplies early in the season, reducing head size and yield. This is illustrated by what happened in 2011 when the experiments were affected by drought. In those situations, yields were maximized with more than two heads per plant because the lowest plant populations produced the greatest yield.

Insert link to file: Grain Sorghum Planting Date Maturity Row Spacing and Seeding Rate.pdf

Improving the Performance of Winter Wheat Planted Without Tillage after Grain Sorghum

Contributors: Josh Jennings, Kraig Roozeboom, and J. Randall Nelson

Over the past two decades no-till management systems have increased in acres throughout Kansas. No-till has improved soil water conservation while helping reduce soil erosion. The increased amount of available soil water associated with no-till has allowed growers to intensify and diversify their crop rotations. This has resulted in more acres of winter wheat planted following summer row crops. Grain Sorghum and winter wheat are two common crops in Kansas and are adapted to similar growing environments. Previous rotation research has revealed that wheat often performs worse following grain sorghum compared to other summer row crops. The objective of this study was to evaluate various residue and harvest management strategies in no-till systems to improve winter wheat yields following grain sorghum. Three management factors were: glyphosate (pre-harvest application, postharvest application, and no application), residue (residue removal, residue chopped, and residue left standing), and nitrogen (additional 30 lb ac-1 applied to residue and no additional nitrogen applied). The study was conducted at three locations in Kansas that have environments conducive for planting winter wheat following a summer row crop. There was no interaction among the treatments and locations, so results were combined over the three locations. Pre-harvest glyphosate application, leaving sorghum residue in place, and additional nitrogen application tended to result in improved values for most yield components of winter wheat at various stages of development. Wheat yields increased by 5 bu ac-1 with pre-harvest application of glyphosate to the preceding sorghum crop, and decreased by 3 to 4 bu ac-1 with residue chopping or removal. Application of additional nitrogen to the stubble did not improve wheat yields.

Managing Herbicide-resistant Weed Populations in Grain Sorghum – 2,4-D

Contributors: Kraig Roozeboom and Dave Regehr

Many producers are searching for additional, economical options to control broadleaf weeds in sorghum. The tendency of 2,4-D to cause brittle stalks and other plant reactions is well documented. This has caused a movement away from this herbicide in recent years. The limited number of effective herbicides and the onset of triazine- and ALS-resistant amaranth have renewed interest in 2,4-D for weed control in sorghum. The objective of this study was to determine whether current hybrids differ in their response to applications of 2,4-D. Grain sorghum hybrids were arranged in paired plots with and without 2,4-D. All plots were maintained weed-free by pre-emergence herbicides and hand weeding. Plots were arranged in a randomized complete block experimental design. Blocks were split by hybrid maturity to facilitate timely harvest and four-row whole plots of each hybrid were split to provide paired treated vs. untreated two-row subplots. Injury ratings were made at 8, 14, and 21 days after treatment. Anthesis date, plant height, extent of lodging, and grain yield were recorded. No strong winds or storms occurred during the rest of the season, so lodging was minimal. Plant height and grain moisture showed no interaction between hybrid and 2,4-D application. Almost all hybrids showed significant early-season injury and a slight delay in bloom date, but the extent of response differed among hybrids. The effect of 2,4-D application on yield and test weight was not consistent among hybrids. Yield of almost 80% of hybrids was not significantly affected by 2,4-D treatment. Grain yield of two hybrids was significantly greater for treated than untreated subplots. Roughly 20% of hybrids yielded significantly less in treated subplots than in untreated subplots. Grain sorghum hybrids seem to differ in their response to applications of 2,4-D.

Insert link to file: KLR200724DPoster.pdf

Soybean Management

Interaction of Soybean Maturity, Row Spacing, and Seeding Rate

Contributors: Kraig Roozeboom

Several studies have been conducted examining the effect of soybean maturity, row spacing, and seeding rate, but few have facilitated exploration of interactions between all three factors in the western Corn Belt. The objective of this study was to optimize planting practices for non-irrigated soybeans. Field experiments were conducted in 2007-2009 near Manhattan, KS to compare the effect of maturity, row spacing, seeding rate, and their interactions on soybean yield. The MG 4.4 variety produced the greatest yield in 2007, and the MG 3.8 variety yielded most in 2008 and 2009. The MG 4.4 variety was less sensitive to changes in seeding rate than the MG 3.0 or 3.8 varieties. Row spacing did not influence yield and did not interact with maturity or seeding rate. Maximum yields resulted from seeding rates of 120,000 seeds acre-1 and greater in 2008 and 2009 (64 bushels acre-1) and 80,000 seeds acre-1 or greater in 2007 (37 bushels acre-1). The plant populations resulting from those seed rates were approximately 79,000, 97,000, and 113,000 plants acre-1 or greater in 2007, 2008, and 2009, respectively. Planting recommendations for northeast Kansas based on results of these experiments include planting a late MG 3 to early MG 4 variety at seeding rates that will result in 100,000 to 115,000 plants acre-1 with no adjustments necessary for different row spacings.

Insert link to file: KLR ASA Poster SBMRP B.pdf

Soybean Plant Density and Yield

Contributors: Kraig Roozeboom, Stewart Duncan, Tom Maxwell, Dave Regehr, William Schapaugh, Larry Maddux, Barney Gordon, Greag McClure

County Extension agents often conduct demonstrations that include the same treatments being examined by on-station researchers. On-farm plots serve as effective demonstrations of the principles documented in on-station studies. However, results from on-farm demonstrations seldom are utilized beyond the borders of that county or district. Our goal was to use a series of on-farm and on-station studies examining soybean plant populations to enhance the breadth of information collected and its educational value. During 2006 and 2007, county agents, Extension specialists, and researchers from K-State conducted 26 experiments examining soybean seeding rates. Five experiments were located on research stations and 21 were on producers’ fields. Some on-farm experiments were replicated and some were not. The studies encompassed a wide range of production practices, environmental conditions, and productivity. Average test yields ranged from 12 to 78 bushels per acre. Yields from all studies were standardized to percent of the test average to facilitate fitting response curves. Results were summarized by yield level to determine if the optimal population changed depending on yield potential. Yields tended to increase in response to increasing population up to a point. In low-yield environments, yields reached a plateau at a population of about 75,000 plants per acre. In environments with average or greater yields, a population of 110,000 plants per acre was sufficient to maximize yield. At seeding rates less than 150,000 seeds per acre, field emergence ranged from less than 50% to near 100%, averaging close to 80%. When more than 150,000 seeds per acre were planted, emergence averaged 75%. The results reinforced current recommendations and confirmed their validity for additional areas of the state and production systems. Active participation of county agents, area specialists, and producers enhanced the credibility of the results and served as a springboard for dissemination of recommendations.

Insert link to file: SB Pops ASA.pdf

Interactions of Planting Date, Seed Treatment, and Foliar Fungicides

Contributors: Stewart Duncan, Kraig Roozeboom, Doug Jardine

The advent of seed treatments that combine fungicidal and insecticidal activity combined with a selection of effective foliar fungicides provides soybean growers with an ever-increasing number of management options. Optimizing combinations of these management tools is necessary for maximizing yield and profit for soybeans in Kansas. The objectives of this study were to investigate response of soybeans to both seed and foliar fungicides at two planting dates under dryland and irrigated conditions and to assess the role of fungicides in improving the quality of soybean seed for planting. Field experiments were conducted on silt-loam soils at three Kansas locations in 2009 and 2010: Scandia, irrigated, Belleville, and Manhattan. Seed treatments were either untreated or treated with CruiserMaxx. A number of foliar fungicides were applied at R2 to R3. Results revealed relationships between all treatment factors. Early planting consistently yielded more than late planting. Seed treatments improved soybean plant populations and yield in most situations, but yield increases were minimal with early June planting. Foliar fungicides consistently reduced disease incidence and delayed senescence and maturation, but did not provide consistent yield or seed size increases in these environments.

Insert link to file: SBPDSTFF Soybean Expo Poster.pdf

Evaluation of Soybean Inoculant Products and Techniques to Address Soybean Nodulation Problems in Kansas

Contributors: Kim Larson, Kraig Roozeboom, Charles Rice

Soybean acreage has been expanding in Kansas, and soybeans are increasingly being planted in fields where the crop has not been grown previously. Nodulation issues have been encountered on several these “new” soybean fields. The purpose of this study was to aid in understanding and improving the consistency of soybean nodulation and production, especially on new soybean ground. The research objective was to evaluate soybean nodulation performance on fields with varying soybean history with different inoculants and seed treatments. The study was split into two parts. One focused on different inoculant products along with 2X rates and product combinations that are often recommended for land not previously planted to soybeans. The second focused on single-rate inoculant products applied with different combinations of fungicide, insecticide, and nematicide seed treatments.

In the first study, the Novozymes inoculant products generally provided superior nodulation performance over the other company products in the study. The combination of dry and liquid inoculant products provided a significant increase in root nodule number at 3 of 5 sites in 2012. We observed no consistent response to higher rates or inoculant combinations over single rates in 2011. Although there were early season nodulation differences between treatments in new soybean ground, these did not carry through to harvest yield differences in the majority of research sites. Hot and dry summer conditions likely reduced yields, making detection of treatment differences difficult. In the second study, none of the seed treatments had negative effects on nodulation performance. There were significant differences in yield between treatments at one location in 2011, but differences were small, and the raw seed yielded as well or better than all treatment/inoculant combinations. At the other sites in both years, yield was not significantly influenced by seed treatment and inoculant combinations.

Insert link to file: 2012 Soybean Expo Poster KLR.pdf

Agronomic Maximization of Soybean Yield and Quality: Row Spacing x Management Interaction

Contributors: Bryson Haverkamp, Eric W. Wilson, Kraig L. Roozeboom, Seth L. Naeve

Yield-enhancing products in soybeans have become increasingly popular in recent years in response to higher commodity prices. However, little research has been done looking at the combinations of these products with different production practices. Narrow row spacing along with these yield-enhancing products may be an effective way of maximizing soybean yield. The objective of this study was to evaluate the interaction of aggressive and standard soybean management practices with different row spacings. Three row spacings: 25-cm, 51-cm, and 76-cm and four management practices: untreated, fungicide and insecticide seed treatment plus foliar fungicide, “SOYA Complete” (combination of several seed treatments, nitrogen, and numerous foliar products), and “SOYA Complete” minus foliar fungicide were evaluated at five locations (three in Kansas and two in Minnesota) in 2012 and 2013. In Kansas, no significant differences in yield were found between the three row spacings across all locations. The fungicide and insecticide seed treatment plus foliar fungicide yielded significantly more at one location. Stand counts taken at V2/V3 and R8 improved with increasing row spacing at one location. The untreated and fungicide and insecticide seed treatments plus foliar fungicide managements had consistently higher stand counts at two locations. With 2012 precipitation being 34.9cm below the 30-year average and above normal average high temperatures during the growing season, some main effects may have been hidden. Response to aggressive soybean management practices did not depend on row spacing.

Insert link to file: Soybean Management CSSA Poster 2013.pdf


Residue Management to Improve Establishment and Survival in No-Till Canola

Contributors: Kraig Roozeboom, Vic Martin, Michael Stamm

Winter stand loss in no-till canola has been identified over the past several years as a key barrier in no-till canola production in the southern Great Plains. On-farm observations indicated that residue increased the height of the crown of canola plants, perhaps making them more susceptible to injury from cold temperatures and desiccation. Observations of other crops grown in no-till vs. conventional tillage indicated a possible difference in near-surface temperatures (soil and air). The purpose of these experiments was to identify the underlying causes of winter stand loss in no-till canola and to create management strategies to improve winter survival in no-till canola production. The specific objectives are to examine the influence of residue and tillage on stand establishment and winter survival. Treatments included light disking (Conventional), no-till (No-Till), no-till with residue removed (NT-No Residue), no-till with twice as much residue (NT-2X Residue), and no-till with residue burned at planting (NT-Burn). The experiments were established on long-term no-till sites, usually on private farms. Soil temperatures in the seed zone and soil moisture were monitored throughout the winter until bolting in the spring. Winter stand loss, plant vigor at key points in plant development, and other measures of crop development and yield were recorded. Results indicated that residue amount influenced development of canola plants as measured by crown height and fall vigor. These differences were most likely caused by differences in amount of residue and not by tillage because the Conventional, NT-Burn, and NT-No Residue treatments had similar values for residue amount, crown height, and vigor. Canola plants in plots with greater amounts of residue had increased crown height and less vigor. Reducing residue allowed the crown to remain closer to the soil surface, had little effect on stand establishment and amount of fall growth, resulted in greater fall vigor of canola plants (greater resistance to fall freezes), enabled canola to better survive the winter, and resulted in greater canola yield. This work supports the conclusion that it is not necessary to till to realize benefits of residue removal.

Insert link to file: NT Canola Establishment Survival.pdf

Winter Canola Yield and Survival Response to Planting Date, Tillage, and Genotype

Contributors: Kraig Roozeboom, Michael Stamm, Yared Assefa

Successful winter canola production creates diversity and provides crop rotation alternatives for producers. Among the main constraints for successful winter canola production are stand establishment and winter survival. The objective of this research was to investigate the impact of planting date, tillage, and genetics on canola stand establishment, winter survival, and yield. Experiments were conducted for three years (2010-2012) in Manhattan, Kansas. Results suggest that early planting, in mid to late August and early September, resulted in improved winter survival and yield compared to planting late in September or early October. Tillage improved winter survival and yield compared to no-till, but differences were minimized with early planting. Crown height of canola was greater in no-till treatments compared to conventional tillage treatments. However, a significant relationship was not identified between crown height and winter survival or yield to prove our initial hypothesis that increased height of crown makes canola plants more susceptible to cold injury. Cultivars did show significant differences in yield, survival, and crown height, but their responses were similar in both tilled and no-till management scenarios.

Insert link to file: Canola Planting Date x Tillage x Genotype.pdf