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Papers by Alan Schlegel

Presented at the 2006 Central Plains irrigation conference on February 21-22 in Colby, Kansas.

Water shortage is the primary factor limiting crop production in the USA’s westcentral Great Plai... more Water shortage is the primary factor limiting crop production in the USA’s westcentral Great Plains, and agricultural sustainability depends on efficient use of water resources. Precipitation is limited and sporadic with mean annual precipitation ranging from 16 to 20 inches across the region, which is only 6080% of the seasonal water use for corn. Yields of dryland crops are limited and variable and some producers have used irrigation to mitigate these effects. Continued declines within the Ogallala Aquifer will result in a further shift from fully irrigated to deficit or limited irrigation or even dryland production in some areas. As this occurs, producers will desire to maintain crop production levels as great as possible while balancing crop production risks imposed by constraints on water available for production. Efficient utilization of plant available soil water (PASW) reserves is important for both dryland and irrigated summer crop production systems.

Agronomy Journal

Most dryland soil and crop management systems are geared toward improving amount and use of avail... more Most dryland soil and crop management systems are geared toward improving amount and use of available soil water (ASW) at planting (ASWP) and in-season precipitation (ISP). Th e relationship between ASWP and yield has seldom been a singular research focus. Th e objective of this study was to investigate the eff ect of diff erent levels of ASWP on yield and water productivity of dryland corn (Zea mays L.) and grain sorghum [Sorghum bicolor (L.) Moench]. Th e study was conducted at two locations, Tribune and Colby, KS, for 3 yr, 2012 to 2014. Four diff erent levels of ASWP were established by applying irrigation prior to planting (0, 38, 76, or 114 mm). Corn and sorghum yield increased in response to increased ASWP but yield gains per millimeter of ASWP decreased as ISP increased. Corn yield gain was in the range of 27 to 33 kg ha-1 (mm ASWP)-1 when ISP was in the range of 196 to 215 mm and yield gain decreased to 9 to 25 kg ha-1 (mm ASWP)-1 when ISP increased to 288 to 354 mm. Similarly, grain sorghum yield response to ASWP decreased from 12 to 22 kg ha-1 to 0 to 6 kg ha-1 per millimeter ASWP when ISP increased from 163 to 281 mm to a range of 315 to 382 mm. We concluded that dryland corn and grain sorghum yield increased with increased level of ASWP and a signifi cant contribution of ASWP to yield production is realized when ISP is low.

Kansas Agricultural Experiment Station Research Reports

Occasional tillage ahead of winter wheat planting could alleviate herbicide-resistant weeds, redi... more Occasional tillage ahead of winter wheat planting could alleviate herbicide-resistant weeds, redistribute soil acidification, and improve seedbed at wheat planting. The objective of this study is to determine occasional tillage and nitrogen (N) fertilizer application effects on winter wheat, and grain sorghum yields and soil quality in a wheat-sorghum-fallow cropping system. Treatments were three tillage practices: 1) continuous no-tillage (NT); 2) continuous reduced-tillage (RT); and 3) single tillage operation every 3 years (June-July) ahead of winter wheat planting [occasional tillage (OT)]. The sub-plot treatments were assigned to four N fertilizer rates (0, 40, 80 and 120 lb/a of N). Preliminary results showed tillage had no effect on winter wheat grain yield. Applying N fertilizer increased wheat yield, ranging from 21 bu/a with no N fertilizer to 29 bu/a when N fertilizer was applied at 120 lb/a of N. Tillage and N fertilizer effects on grain sorghum yield varied over the 2 years of the study. Grain sorghum yields in 2017 decreased with RT but tillage had no effect on sorghum yields in 2018. Averaged across tillage and years, sorghum grain yield was 54 bu/a with no N fertilizer and 84 bu/a when N was applied at 120 lb/a of N. Both sorghum and winter wheat grain yields obtained with 80 lb/a of N were not different from those with 120 lb/a of N, suggesting 80 lb/a of N may be adequate for both crops.

Agronomy Journal

Dryland crop rotation systems are sustainable only if there is sufficient water available for pro... more Dryland crop rotation systems are sustainable only if there is sufficient water available for profitable crop production. The objective of our study was to identify potential crop rotation systems for the central Great Plains and similar semiarid areas that increase soil water, fallow water accumulation, fallow efficiency, and water productivity of major crops. The study was conducted from 2000 through 2017 near Tribune, KS. Four summer crops [corn (Zea mays L.) (CR), grain sorghum (Sorghum bicolor L.) (GS), soybean (Glycine max L.) (SB), and sunflower (Helianthus annuus L.) (SF)] along with winter wheat (Triticum aestivum L.) (W) were grown in 1-, 2-, 3-, and 4-yr rotations, with most rotations including a fallow (F) phase.

Crop Science

Growing a crop in place of fallow may improve soil properties but result in reduced soil water an... more Growing a crop in place of fallow may improve soil properties but result in reduced soil water and crop yields in semiarid regions. This study assessed the effect of replacing fallow in no-till winter wheat (Triticum aestivum L.)-fallow with cover, forage, or grain crops on plant available water (PAW), wheat yield, grain quality, and profitability over 5 yr, from 2007 to 2012. Plant available water at wheat planting was reduced the most when the fallow period was the shortest (i.e., following grain crops) or when biomass production was the greatest. Winter and spring lentil (Lens culinaris Medik.) produced the least biomass, used the least soil water, and had the least negative effect on yield. For every 125 kg ha −1 of cover or forage biomass grown, PAW was reduced by 1 mm, and for every millimeter of PAW, wheat yield was increased by 5.5 kg ha −1. There was no difference in wheat yield whether the preceding crop was harvested for forage or left as standing cover. In years with above-average precipitation, wheat yield was reduced 0 to 34% by growing a crop in place of fallow. However, in years with below-average precipitation, wheat yield was reduced 40 to 70% without fallow. There was minimal negative impact on wheat yield growing a cover or forage crop in place of fallow if wheat yield potential was 3500 kg ha −1 or greater. Net returns were reduced 50 to 100% by growing a cover crop. However, net returns were increased 26 to 240% by growing a forage crop. Integrating annual forages into the fallow period in semiarid regions has the greatest potential for adoption.

Kansas Agricultural Experiment Station Research Reports

Drilled sorghum is normally done at the super-high population at row spacing between 7.5 and 10 i... more Drilled sorghum is normally done at the super-high population at row spacing between 7.5 and 10 inches, compared to rows planted at the spacing between 15 and 30 inches. Thompson (1983) growing superthick sorghum at the Hays Research Station from 1974-1977, found that sorghum planted in narrow rows (12-18 in.) often produced higher yields than when planted in wide rows (24-40 in.). Norwood (1982) in Garden City repeated Thompson's work and also came to the conclusion that yield of high population narrow row sorghum could exceed that of the low population-wide row when subsoil moisture and precipitation were adequate. The conclusion from the work of Thompson and Norwood was that subsoil moisture and precipitation was big drivers for the high population, narrow-row sorghum to equal or exceed the yield of the low population-wide row. Since then, most researchers have found yield response to plant population to be variable depending on the environment. Overall, the general consensus is that under conditions of adequate moisture, the yield of high population sorghum can continue to increase, but can decrease under dry conditions. Today moisture still remains the key for successful dryland sorghum production in southwest Kansas. Thus, the very familiar saying, "moisture and fertility are joined at the hip." Thompson's and Norwood's work did not evaluate narrow row at population under 25,000 seeds/A and at a spacing below 10 in. We hypothesized that drilled sorghum at lower population could make better use of water resources and produce similar yields to drilled sorghum at higher population, and planted sorghum at the same population. Thus, the objective of this study is to evaluate drilled sorghum at different populations ranging from 20,000 to 80,000 seeds/A at a row spacing of 10 in. or less at different nitrogen rates. Furthermore, most farmers in southwest Kansas own both a drill and a planter. Thus, it is not just an agronomic issue, but it is also about getting better value from a single piece of equipment in an already economically challenging wheat-sorghum-fallow production system.

Kansas Agricultural Experiment Station Research Reports

Annual forages are an important crop in the High Plains, yet the region lacks recommended annual ... more Annual forages are an important crop in the High Plains, yet the region lacks recommended annual forage rotations compared to those developed for grain crops. Forages are important for the region's livestock and dairy industries and are becoming increasingly important as irrigation capacity and grain prices decrease. Forages require less water than grain crops and may allow for increased cropping system intensity and opportunistic cropping. A study was initiated in 2012 at the Southwest Research-Extension Center near Garden City, KS, comparing several 1-, 3-, and 4-year forage rotations with no-tillage and minimum-tillage. Data presented are from 2013 through 2017. Tillage generally increased winter triticale yields 1,250 lb/a compared to no-till yields, due in part to increased plant available water. Plant available water at planting winter triticale averaged 5.2 in./a in min-till and 3.4 in./a in no-till. Double-crop forage sorghum yielded 22% less than full-season forage sorghum and yields were not affected by tillage. Oat yields were lower than forage sorghum or winter triticale yields. Subsequent years will be used to further compare forage rotations, develop crop-water relationships, and establish partial enterprise budgets.

Agricultural Water Management

Due to inadequate irrigation capacity, some farmers in the United States High Plains apply prepla... more Due to inadequate irrigation capacity, some farmers in the United States High Plains apply preplant irrigation to buffer the crop between irrigation events during the cropping season. The purpose of the study was to determine preplant irrigation amount and irrigation capacity combinations that optimize yield, water productivity, and precipitation use efficiency (PUE) and minimize soil water evaporation losses prior to planting. The CERES-Maize model embedded in the RZWQM2 model in combination with long-term climatic data from 1986 to 2014 for southwest Kansas were used for this research. Experimental data from 2006 to 2009 was used to calibrate and validate the model. Model performance was satisfactory with high index of agreement (IA > 0.88). Relative root mean square error (RRMSE) ranged between 4.5% and 27%. Under very limited irrigation capacity (2.5 mm/day), applying 75-100 mm of preplant irrigation produced median yields that were 10-17% higher than not applying preplant irrigation. However, even at limited irrigation capacity the benefit of preplant irrigation were only realized if the seasonal yield potential was in the range of 6000 to 10,000 kg/ha corresponding to years with normal seasonal rainfall. Irrigation capacity had a stronger effect on maize grain yield compared to preplant irrigation amount. Preplant irrigation increased ET and transpiration under 2.5 mm/day irrigation capacity. Preplant irrigation amount did not have a substantial impact on water productivity at high and moderate irrigation capacity but had second order dominant effect under limited irrigation capacity. At low irrigation capacity (2.5 mm/day) increasing preplant irrigation increased median PUE up to 18% although the effect was second order dominant. Negligible water losses through deep percolation from 2.4 m soil profile were simulated. Increasing preplant irrigation resulted in significantly higher soil water evaporation losses prior to planting at all irrigation capacities. Overall preplant irrigation is beneficial under very limited irrigation capacity but is not necessary under sufficient irrigation capacity in most years. The decision to apply preplant irrigation should be evaluated and implemented carefully in combination with other agricultural water management technologies and strategies such as soil water monitoring, drip irrigation, and residue management.

Kansas Agricultural Experiment Station Research Reports

Grain yields of wheat and grain sorghum increased with decreased tillage intensity in a wheat-sor... more Grain yields of wheat and grain sorghum increased with decreased tillage intensity in a wheat-sorghumfallow (WSF) rotation. In 2014, available soil water at wheat planting was 2 inches greater for no-till (NT) than for reduced-tillage (RT) or conventional tillage (CT). For grain sorghum in 2014, available soil water at planting was greatest with RT and least with CT. Averaged across the 14-year study, available soil water at wheat and sorghum planting was similar for RT and NT and about 1 inch greater than CT. Averaged across the past 14 years, NT wheat yields were 5 bu/a greater than RT and 7 bu/a greater than CT. Grain sorghum yields in 2014 were 22 bu/a greater with longterm NT than short-term NT. Averaged across the past 14 years, sorghum yields with long-term NT have been nearly twice as great as short-term NT (61 vs. 33 bu/a).

Kansas Agricultural Experiment Station Research Reports

Forage production is important for the western Kansas region's livestock and dairy industries and... more Forage production is important for the western Kansas region's livestock and dairy industries and has become increasingly important as irrigation-well capacity declines. Forages require less water than grain crops and may allow for increased cropping intensity and opportunistic cropping. Being able to estimate forage production is important for determining forage availability versus forage needs. Data from several studies were used to quantify annual forage yield response to plant available water (PAW) at planting and growing season precipitation (GSP). In addition, water use efficiency was quantified. Forages evaluated included winter triticale, spring triticale, and forage sorghum. Preliminary results showed PAW and GSP explained 26% of the variability in forage sorghum yield. Winter triticale yield increased by 640 lb/a for every inch of water use (PAW plus GSP). However, spring triticale produced only 193 lb/a for every inch of water use. The low correlation with water use and spring triticale yield suggests other factors, such as temperature, affect spring forage production more than soil moisture.

Kansas Agricultural Experiment Station Research Reports

Beginning in 2012, research was conducted in Garden City and Tribune, KS, to determine the effect... more Beginning in 2012, research was conducted in Garden City and Tribune, KS, to determine the effect of a single tillage operation every 3 years on grain yields in a wheat-sorghum-fallow (WSF) rotation. Grain yields of wheat and grain sorghum were generally not affected by a single tillage operation every 3 years in a WSF rotation. Grain yield varied greatly by year from 2014 to 2020. Wheat yields ranged across years from mid-20s to 90 bu/a at Tribune and less than 10 to 100 bu/a at Garden City. Grain sorghum yields ranged from 40 to greater than 140 bu/a, depending upon year and location. In 2019 wheat yields at Garden City were less when tillage was implemented post-wheat harvest in 2016. There were no other years or locations where grain yields were significantly affected by a single tillage operation. However, at Tribune, when averaged across the 7-year period, a single tillage after wheat harvest reduced grain sorghum yields compared to a complete no-till (NT) system. At Garden City, averaged across the 7-year period, wheat yields were not different, but tended to be greater following a single one-time tillage prior to wheat. This indicates that if a single tillage operation is needed to control troublesome weeds, that tillage during fallow prior to wheat planting may be better than tillage after wheat harvest. This study supports the hypothesis that if herbicide-resistant weed populations are high enough to cause yield reductions, then tillage might improve yields.

Kansas Agricultural Experiment Station Research Reports

Four winter wheat varieties (

Kansas Agricultural Experiment Station Research Reports

A limited irrigation study involving four cropping systems and evaluating four crop rotations was... more A limited irrigation study involving four cropping systems and evaluating four crop rotations was initiated at the Southwest Research-Extension Center near Tribune, KS, in 2012. The cropping systems were two annual systems (continuous corn and continuous grain sorghum) and two 2-year systems (corn-grain sorghum and corn-winter wheat). In 2020, corn yields were similar for all rotations, although averaged across the past 8 years, corn yields were greater following wheat than following corn. There were no significant differences in grain sorghum yields in 2020, which was similar to the multi-year average. Wheat yields were below the multi-year average.

Kansas Agricultural Experiment Station Research Reports

A field study initiated in 2006 at the Southwest Research-Extension Center near Tribune, KS, was ... more A field study initiated in 2006 at the Southwest Research-Extension Center near Tribune, KS, was designed to evaluate the effects of three wheat stubble heights on subsequent grain yields of corn and grain sorghum. Corn and sorghum yields in 2020 were near the long-term average despite lower than normal precipitation. When averaged across years from 2007 through 2020, corn grain yields were 8 bu/a greater when planted into either high or strip-cut wheat stubble than into low-cut stubble. Average grain sorghum yields were 5 bu/a greater in high-cut stubble than low-cut stubble. Similarly, water use efficiency was greater for high or strip-cut stubble for corn, and greater for high-cut stubble for grain sorghum than for low-cut stubble. Harvesting wheat stubble shorter than necessary causes a yield penalty for the subsequent corn and grain sorghum crops.

Kansas Agricultural Experiment Station Research Reports

This study was conducted from 2008-2020 at the Kansas State University Southwest Research-Extensi... more This study was conducted from 2008-2020 at the Kansas State University Southwest Research-Extension Center near Tribune, KS. The purpose of the study was to identify whether more intensive cropping systems can enhance and stabilize production in rainfed cropping systems to optimize economic crop production, more efficiently capture and utilize scarce precipitation, and maintain or enhance soil resources and environmental quality. The crop rotations evaluated were continuous grain sorghum (SS), wheat-fallow (WF), wheat-corn-fallow (WCF), wheat-sorghum-fallow (WSF), wheat-cornsorghum-fallow (WCSF), and wheat-sorghum-corn-fallow (WSCF). All rotations were grown using notillage (NT) practices except for WF, which was grown using reduced-tillage. The efficiency of precipitation capture was not greater with more intensive rotations. Length of rotation had little effect on wheat yields. Corn and grain sorghum yields were approximately 50% greater when following wheat than when following corn or grain sorghum. Grain sorghum yields were approximately 40% greater than corn in similar rotations.

Kansas Agricultural Experiment Station Research Reports

In 1996, an effort began to quantify soil water storage, crop water use, and crop productivity on... more In 1996, an effort began to quantify soil water storage, crop water use, and crop productivity on dryland systems in western Kansas. Research on 4-year crop rotations with wheat and grain sorghum was initiated at the Southwest Research-Extension Center near Tribune, KS. Rotations were wheat-wheatsorghum-fallow (WWSF), wheatsorghum-sorghum-fallow (WSSF), and continuous wheat (WW). Soil water at wheat planting averaged about 9 in. following sorghum, which is about 3 in. more than the average for the second wheat crop in a WWSF rotation. Soil water at sorghum planting was only about 1 in. less for the second sorghum crop compared with sorghum following wheat. Grain yield of recrop wheat averaged about 80% of the yield of wheat following sorghum. Grain yield of continuous wheat averaged about 65% of the yield of wheat grown in a 4-year rotation following sorghum. Generally, wheat yields were similar following one or two sorghum crops. Similarly, average sorghum yields were the same following one or two wheat crops. Yield of the second sorghum crop in a WSSF rotation averaged ~65% of the yield of the first sorghum crop.

Kansas Agricultural Experiment Station Research Reports

Grain yields of wheat and grain sorghum increased with decreased tillage intensity in a wheat-sor... more Grain yields of wheat and grain sorghum increased with decreased tillage intensity in a wheat-sorghum-fallow (WSF) rotation. In 2015, available soil water at wheat planting was greater for no-till (NT) and reduced till (RT) than for conventional till (CT). Similarly, for grain sorghum in 2015, available soil water at planting was increased with NT or RT and least with CT. Averaged across the 15-yr study, available soil water at wheat and sorghum planting was similar for RT and NT and about 1 inch greater than CT. Averaged across the past 15 years, NT wheat yields were 5 bu/a greater than RT and 7 bu/a greater than CT. Grain sorghum yields in 2015 were 42 bu/a greater with long-term NT than short-term NT. Averaged across the past 15 years, sorghum yields with long-term NT have been nearly twice as great as short-term NT (64 vs. 35 bu/a).

Presented at the 2006 Central Plains irrigation conference on February 21-22 in Colby, Kansas.

Water shortage is the primary factor limiting crop production in the USA’s westcentral Great Plai... more Water shortage is the primary factor limiting crop production in the USA’s westcentral Great Plains, and agricultural sustainability depends on efficient use of water resources. Precipitation is limited and sporadic with mean annual precipitation ranging from 16 to 20 inches across the region, which is only 6080% of the seasonal water use for corn. Yields of dryland crops are limited and variable and some producers have used irrigation to mitigate these effects. Continued declines within the Ogallala Aquifer will result in a further shift from fully irrigated to deficit or limited irrigation or even dryland production in some areas. As this occurs, producers will desire to maintain crop production levels as great as possible while balancing crop production risks imposed by constraints on water available for production. Efficient utilization of plant available soil water (PASW) reserves is important for both dryland and irrigated summer crop production systems.

Agronomy Journal

Most dryland soil and crop management systems are geared toward improving amount and use of avail... more Most dryland soil and crop management systems are geared toward improving amount and use of available soil water (ASW) at planting (ASWP) and in-season precipitation (ISP). Th e relationship between ASWP and yield has seldom been a singular research focus. Th e objective of this study was to investigate the eff ect of diff erent levels of ASWP on yield and water productivity of dryland corn (Zea mays L.) and grain sorghum [Sorghum bicolor (L.) Moench]. Th e study was conducted at two locations, Tribune and Colby, KS, for 3 yr, 2012 to 2014. Four diff erent levels of ASWP were established by applying irrigation prior to planting (0, 38, 76, or 114 mm). Corn and sorghum yield increased in response to increased ASWP but yield gains per millimeter of ASWP decreased as ISP increased. Corn yield gain was in the range of 27 to 33 kg ha-1 (mm ASWP)-1 when ISP was in the range of 196 to 215 mm and yield gain decreased to 9 to 25 kg ha-1 (mm ASWP)-1 when ISP increased to 288 to 354 mm. Similarly, grain sorghum yield response to ASWP decreased from 12 to 22 kg ha-1 to 0 to 6 kg ha-1 per millimeter ASWP when ISP increased from 163 to 281 mm to a range of 315 to 382 mm. We concluded that dryland corn and grain sorghum yield increased with increased level of ASWP and a signifi cant contribution of ASWP to yield production is realized when ISP is low.

Kansas Agricultural Experiment Station Research Reports

Occasional tillage ahead of winter wheat planting could alleviate herbicide-resistant weeds, redi... more Occasional tillage ahead of winter wheat planting could alleviate herbicide-resistant weeds, redistribute soil acidification, and improve seedbed at wheat planting. The objective of this study is to determine occasional tillage and nitrogen (N) fertilizer application effects on winter wheat, and grain sorghum yields and soil quality in a wheat-sorghum-fallow cropping system. Treatments were three tillage practices: 1) continuous no-tillage (NT); 2) continuous reduced-tillage (RT); and 3) single tillage operation every 3 years (June-July) ahead of winter wheat planting [occasional tillage (OT)]. The sub-plot treatments were assigned to four N fertilizer rates (0, 40, 80 and 120 lb/a of N). Preliminary results showed tillage had no effect on winter wheat grain yield. Applying N fertilizer increased wheat yield, ranging from 21 bu/a with no N fertilizer to 29 bu/a when N fertilizer was applied at 120 lb/a of N. Tillage and N fertilizer effects on grain sorghum yield varied over the 2 years of the study. Grain sorghum yields in 2017 decreased with RT but tillage had no effect on sorghum yields in 2018. Averaged across tillage and years, sorghum grain yield was 54 bu/a with no N fertilizer and 84 bu/a when N was applied at 120 lb/a of N. Both sorghum and winter wheat grain yields obtained with 80 lb/a of N were not different from those with 120 lb/a of N, suggesting 80 lb/a of N may be adequate for both crops.

Agronomy Journal

Dryland crop rotation systems are sustainable only if there is sufficient water available for pro... more Dryland crop rotation systems are sustainable only if there is sufficient water available for profitable crop production. The objective of our study was to identify potential crop rotation systems for the central Great Plains and similar semiarid areas that increase soil water, fallow water accumulation, fallow efficiency, and water productivity of major crops. The study was conducted from 2000 through 2017 near Tribune, KS. Four summer crops [corn (Zea mays L.) (CR), grain sorghum (Sorghum bicolor L.) (GS), soybean (Glycine max L.) (SB), and sunflower (Helianthus annuus L.) (SF)] along with winter wheat (Triticum aestivum L.) (W) were grown in 1-, 2-, 3-, and 4-yr rotations, with most rotations including a fallow (F) phase.

Crop Science

Growing a crop in place of fallow may improve soil properties but result in reduced soil water an... more Growing a crop in place of fallow may improve soil properties but result in reduced soil water and crop yields in semiarid regions. This study assessed the effect of replacing fallow in no-till winter wheat (Triticum aestivum L.)-fallow with cover, forage, or grain crops on plant available water (PAW), wheat yield, grain quality, and profitability over 5 yr, from 2007 to 2012. Plant available water at wheat planting was reduced the most when the fallow period was the shortest (i.e., following grain crops) or when biomass production was the greatest. Winter and spring lentil (Lens culinaris Medik.) produced the least biomass, used the least soil water, and had the least negative effect on yield. For every 125 kg ha −1 of cover or forage biomass grown, PAW was reduced by 1 mm, and for every millimeter of PAW, wheat yield was increased by 5.5 kg ha −1. There was no difference in wheat yield whether the preceding crop was harvested for forage or left as standing cover. In years with above-average precipitation, wheat yield was reduced 0 to 34% by growing a crop in place of fallow. However, in years with below-average precipitation, wheat yield was reduced 40 to 70% without fallow. There was minimal negative impact on wheat yield growing a cover or forage crop in place of fallow if wheat yield potential was 3500 kg ha −1 or greater. Net returns were reduced 50 to 100% by growing a cover crop. However, net returns were increased 26 to 240% by growing a forage crop. Integrating annual forages into the fallow period in semiarid regions has the greatest potential for adoption.

Kansas Agricultural Experiment Station Research Reports

Drilled sorghum is normally done at the super-high population at row spacing between 7.5 and 10 i... more Drilled sorghum is normally done at the super-high population at row spacing between 7.5 and 10 inches, compared to rows planted at the spacing between 15 and 30 inches. Thompson (1983) growing superthick sorghum at the Hays Research Station from 1974-1977, found that sorghum planted in narrow rows (12-18 in.) often produced higher yields than when planted in wide rows (24-40 in.). Norwood (1982) in Garden City repeated Thompson's work and also came to the conclusion that yield of high population narrow row sorghum could exceed that of the low population-wide row when subsoil moisture and precipitation were adequate. The conclusion from the work of Thompson and Norwood was that subsoil moisture and precipitation was big drivers for the high population, narrow-row sorghum to equal or exceed the yield of the low population-wide row. Since then, most researchers have found yield response to plant population to be variable depending on the environment. Overall, the general consensus is that under conditions of adequate moisture, the yield of high population sorghum can continue to increase, but can decrease under dry conditions. Today moisture still remains the key for successful dryland sorghum production in southwest Kansas. Thus, the very familiar saying, "moisture and fertility are joined at the hip." Thompson's and Norwood's work did not evaluate narrow row at population under 25,000 seeds/A and at a spacing below 10 in. We hypothesized that drilled sorghum at lower population could make better use of water resources and produce similar yields to drilled sorghum at higher population, and planted sorghum at the same population. Thus, the objective of this study is to evaluate drilled sorghum at different populations ranging from 20,000 to 80,000 seeds/A at a row spacing of 10 in. or less at different nitrogen rates. Furthermore, most farmers in southwest Kansas own both a drill and a planter. Thus, it is not just an agronomic issue, but it is also about getting better value from a single piece of equipment in an already economically challenging wheat-sorghum-fallow production system.

Kansas Agricultural Experiment Station Research Reports

Annual forages are an important crop in the High Plains, yet the region lacks recommended annual ... more Annual forages are an important crop in the High Plains, yet the region lacks recommended annual forage rotations compared to those developed for grain crops. Forages are important for the region's livestock and dairy industries and are becoming increasingly important as irrigation capacity and grain prices decrease. Forages require less water than grain crops and may allow for increased cropping system intensity and opportunistic cropping. A study was initiated in 2012 at the Southwest Research-Extension Center near Garden City, KS, comparing several 1-, 3-, and 4-year forage rotations with no-tillage and minimum-tillage. Data presented are from 2013 through 2017. Tillage generally increased winter triticale yields 1,250 lb/a compared to no-till yields, due in part to increased plant available water. Plant available water at planting winter triticale averaged 5.2 in./a in min-till and 3.4 in./a in no-till. Double-crop forage sorghum yielded 22% less than full-season forage sorghum and yields were not affected by tillage. Oat yields were lower than forage sorghum or winter triticale yields. Subsequent years will be used to further compare forage rotations, develop crop-water relationships, and establish partial enterprise budgets.

Agricultural Water Management

Due to inadequate irrigation capacity, some farmers in the United States High Plains apply prepla... more Due to inadequate irrigation capacity, some farmers in the United States High Plains apply preplant irrigation to buffer the crop between irrigation events during the cropping season. The purpose of the study was to determine preplant irrigation amount and irrigation capacity combinations that optimize yield, water productivity, and precipitation use efficiency (PUE) and minimize soil water evaporation losses prior to planting. The CERES-Maize model embedded in the RZWQM2 model in combination with long-term climatic data from 1986 to 2014 for southwest Kansas were used for this research. Experimental data from 2006 to 2009 was used to calibrate and validate the model. Model performance was satisfactory with high index of agreement (IA > 0.88). Relative root mean square error (RRMSE) ranged between 4.5% and 27%. Under very limited irrigation capacity (2.5 mm/day), applying 75-100 mm of preplant irrigation produced median yields that were 10-17% higher than not applying preplant irrigation. However, even at limited irrigation capacity the benefit of preplant irrigation were only realized if the seasonal yield potential was in the range of 6000 to 10,000 kg/ha corresponding to years with normal seasonal rainfall. Irrigation capacity had a stronger effect on maize grain yield compared to preplant irrigation amount. Preplant irrigation increased ET and transpiration under 2.5 mm/day irrigation capacity. Preplant irrigation amount did not have a substantial impact on water productivity at high and moderate irrigation capacity but had second order dominant effect under limited irrigation capacity. At low irrigation capacity (2.5 mm/day) increasing preplant irrigation increased median PUE up to 18% although the effect was second order dominant. Negligible water losses through deep percolation from 2.4 m soil profile were simulated. Increasing preplant irrigation resulted in significantly higher soil water evaporation losses prior to planting at all irrigation capacities. Overall preplant irrigation is beneficial under very limited irrigation capacity but is not necessary under sufficient irrigation capacity in most years. The decision to apply preplant irrigation should be evaluated and implemented carefully in combination with other agricultural water management technologies and strategies such as soil water monitoring, drip irrigation, and residue management.

Kansas Agricultural Experiment Station Research Reports

Grain yields of wheat and grain sorghum increased with decreased tillage intensity in a wheat-sor... more Grain yields of wheat and grain sorghum increased with decreased tillage intensity in a wheat-sorghumfallow (WSF) rotation. In 2014, available soil water at wheat planting was 2 inches greater for no-till (NT) than for reduced-tillage (RT) or conventional tillage (CT). For grain sorghum in 2014, available soil water at planting was greatest with RT and least with CT. Averaged across the 14-year study, available soil water at wheat and sorghum planting was similar for RT and NT and about 1 inch greater than CT. Averaged across the past 14 years, NT wheat yields were 5 bu/a greater than RT and 7 bu/a greater than CT. Grain sorghum yields in 2014 were 22 bu/a greater with longterm NT than short-term NT. Averaged across the past 14 years, sorghum yields with long-term NT have been nearly twice as great as short-term NT (61 vs. 33 bu/a).

Kansas Agricultural Experiment Station Research Reports

Forage production is important for the western Kansas region's livestock and dairy industries and... more Forage production is important for the western Kansas region's livestock and dairy industries and has become increasingly important as irrigation-well capacity declines. Forages require less water than grain crops and may allow for increased cropping intensity and opportunistic cropping. Being able to estimate forage production is important for determining forage availability versus forage needs. Data from several studies were used to quantify annual forage yield response to plant available water (PAW) at planting and growing season precipitation (GSP). In addition, water use efficiency was quantified. Forages evaluated included winter triticale, spring triticale, and forage sorghum. Preliminary results showed PAW and GSP explained 26% of the variability in forage sorghum yield. Winter triticale yield increased by 640 lb/a for every inch of water use (PAW plus GSP). However, spring triticale produced only 193 lb/a for every inch of water use. The low correlation with water use and spring triticale yield suggests other factors, such as temperature, affect spring forage production more than soil moisture.

Kansas Agricultural Experiment Station Research Reports

Beginning in 2012, research was conducted in Garden City and Tribune, KS, to determine the effect... more Beginning in 2012, research was conducted in Garden City and Tribune, KS, to determine the effect of a single tillage operation every 3 years on grain yields in a wheat-sorghum-fallow (WSF) rotation. Grain yields of wheat and grain sorghum were generally not affected by a single tillage operation every 3 years in a WSF rotation. Grain yield varied greatly by year from 2014 to 2020. Wheat yields ranged across years from mid-20s to 90 bu/a at Tribune and less than 10 to 100 bu/a at Garden City. Grain sorghum yields ranged from 40 to greater than 140 bu/a, depending upon year and location. In 2019 wheat yields at Garden City were less when tillage was implemented post-wheat harvest in 2016. There were no other years or locations where grain yields were significantly affected by a single tillage operation. However, at Tribune, when averaged across the 7-year period, a single tillage after wheat harvest reduced grain sorghum yields compared to a complete no-till (NT) system. At Garden City, averaged across the 7-year period, wheat yields were not different, but tended to be greater following a single one-time tillage prior to wheat. This indicates that if a single tillage operation is needed to control troublesome weeds, that tillage during fallow prior to wheat planting may be better than tillage after wheat harvest. This study supports the hypothesis that if herbicide-resistant weed populations are high enough to cause yield reductions, then tillage might improve yields.

Kansas Agricultural Experiment Station Research Reports

Four winter wheat varieties (

Kansas Agricultural Experiment Station Research Reports

A limited irrigation study involving four cropping systems and evaluating four crop rotations was... more A limited irrigation study involving four cropping systems and evaluating four crop rotations was initiated at the Southwest Research-Extension Center near Tribune, KS, in 2012. The cropping systems were two annual systems (continuous corn and continuous grain sorghum) and two 2-year systems (corn-grain sorghum and corn-winter wheat). In 2020, corn yields were similar for all rotations, although averaged across the past 8 years, corn yields were greater following wheat than following corn. There were no significant differences in grain sorghum yields in 2020, which was similar to the multi-year average. Wheat yields were below the multi-year average.

Kansas Agricultural Experiment Station Research Reports

A field study initiated in 2006 at the Southwest Research-Extension Center near Tribune, KS, was ... more A field study initiated in 2006 at the Southwest Research-Extension Center near Tribune, KS, was designed to evaluate the effects of three wheat stubble heights on subsequent grain yields of corn and grain sorghum. Corn and sorghum yields in 2020 were near the long-term average despite lower than normal precipitation. When averaged across years from 2007 through 2020, corn grain yields were 8 bu/a greater when planted into either high or strip-cut wheat stubble than into low-cut stubble. Average grain sorghum yields were 5 bu/a greater in high-cut stubble than low-cut stubble. Similarly, water use efficiency was greater for high or strip-cut stubble for corn, and greater for high-cut stubble for grain sorghum than for low-cut stubble. Harvesting wheat stubble shorter than necessary causes a yield penalty for the subsequent corn and grain sorghum crops.

Kansas Agricultural Experiment Station Research Reports

This study was conducted from 2008-2020 at the Kansas State University Southwest Research-Extensi... more This study was conducted from 2008-2020 at the Kansas State University Southwest Research-Extension Center near Tribune, KS. The purpose of the study was to identify whether more intensive cropping systems can enhance and stabilize production in rainfed cropping systems to optimize economic crop production, more efficiently capture and utilize scarce precipitation, and maintain or enhance soil resources and environmental quality. The crop rotations evaluated were continuous grain sorghum (SS), wheat-fallow (WF), wheat-corn-fallow (WCF), wheat-sorghum-fallow (WSF), wheat-cornsorghum-fallow (WCSF), and wheat-sorghum-corn-fallow (WSCF). All rotations were grown using notillage (NT) practices except for WF, which was grown using reduced-tillage. The efficiency of precipitation capture was not greater with more intensive rotations. Length of rotation had little effect on wheat yields. Corn and grain sorghum yields were approximately 50% greater when following wheat than when following corn or grain sorghum. Grain sorghum yields were approximately 40% greater than corn in similar rotations.

Kansas Agricultural Experiment Station Research Reports

In 1996, an effort began to quantify soil water storage, crop water use, and crop productivity on... more In 1996, an effort began to quantify soil water storage, crop water use, and crop productivity on dryland systems in western Kansas. Research on 4-year crop rotations with wheat and grain sorghum was initiated at the Southwest Research-Extension Center near Tribune, KS. Rotations were wheat-wheatsorghum-fallow (WWSF), wheatsorghum-sorghum-fallow (WSSF), and continuous wheat (WW). Soil water at wheat planting averaged about 9 in. following sorghum, which is about 3 in. more than the average for the second wheat crop in a WWSF rotation. Soil water at sorghum planting was only about 1 in. less for the second sorghum crop compared with sorghum following wheat. Grain yield of recrop wheat averaged about 80% of the yield of wheat following sorghum. Grain yield of continuous wheat averaged about 65% of the yield of wheat grown in a 4-year rotation following sorghum. Generally, wheat yields were similar following one or two sorghum crops. Similarly, average sorghum yields were the same following one or two wheat crops. Yield of the second sorghum crop in a WSSF rotation averaged ~65% of the yield of the first sorghum crop.

Kansas Agricultural Experiment Station Research Reports

Grain yields of wheat and grain sorghum increased with decreased tillage intensity in a wheat-sor... more Grain yields of wheat and grain sorghum increased with decreased tillage intensity in a wheat-sorghum-fallow (WSF) rotation. In 2015, available soil water at wheat planting was greater for no-till (NT) and reduced till (RT) than for conventional till (CT). Similarly, for grain sorghum in 2015, available soil water at planting was increased with NT or RT and least with CT. Averaged across the 15-yr study, available soil water at wheat and sorghum planting was similar for RT and NT and about 1 inch greater than CT. Averaged across the past 15 years, NT wheat yields were 5 bu/a greater than RT and 7 bu/a greater than CT. Grain sorghum yields in 2015 were 42 bu/a greater with long-term NT than short-term NT. Averaged across the past 15 years, sorghum yields with long-term NT have been nearly twice as great as short-term NT (64 vs. 35 bu/a).