Final report for LS17-286
Project Information
This project funds the maintenance of the long-term field site at the Texas Tech New Deal Research Station in support of long-term sustainability objectives pertaining to the integration of forages and livestock into a predominant row-crop region.
Doctoral research was finished and degrees were conferred in 2018 for 1) analysis of soil microbial communities and horn flies on cattle in pastures (Krishna Bhandari), and 2) cattle grazing teff grass with different protein supplements (Dusty Sugg). Doctoral research in the field was finished and degrees were conferred in 2019 on 1) growth analysis and model development of old world bluestem (OWB) ‘WW-B.Dahl’ (Yedan Xiong), and 2) introduction of alfalfa into dryland native pastures (Madhav Dhakal). Doctoral research was finished in 2020 on determining the effect of including alfalfa in old world bluestem-based pastures on enteric methane emissions from beef cattle and on whole-system water footprint (Kathryn Radicke).
We continued to integrate our efforts with the Texas Alliance for Water Conservation (TAWC) to broaden the impact of grassland water use efficiency. The TAWC involves demonstration and education for local producers on efficient irrigation systems. It is funded by the State of Texas but intersects with this Large Systems SARE-funded project, which serves as a platform for consulting with producers on converting land from irrigated, cultivated row crops to perennial forages as an option to reduce reliance on the Ogallala Aquifer. Visits to the site by producers, students, and other professionals were also conducted during the year.
The overall objectives of crop-livestock research and demonstration projects at Texas Tech University are to (1) understand the biological, environmental, social, economic, and policy issues impacting agricultural sustainability in the Southern High Plains, and (2) to translate research into adoption of more sustainable practices. The Large Systems SARE grant contributes a critical piece of this effort by funding the maintenance of the long-term field research site at the New Deal Research Station, which is the basic platform for our collaborative research and education efforts. The research arm of our effort (Texas Coalition for Sustainable Integrated Systems, TeCSIS) focuses on the integration of forage-based beef production into the region’s predominantly row-crop agriculture as a means of reducing water extraction from the Ogallala Aquifer, building soil organic matter, stabilizing soil from wind erosion, and diversifying income. The outreach arm of our effort is the TAWC, which partners with 20-30 producers to demonstrate improved irrigation practices on around 30 fields near Lubbock, TX. TAWC produces field days, field walks, conferences, radio and TV reports, Twitter and Facebook messages, e-newsletters, and web-based management tools to reach a diverse rural and urban populace on using practical technologies to sustain agriculture and communities. Research at the New Deal Research Station is a source of information pertaining to grazing systems that help meet producers’ goals of stretching water supplies and reverting cropland to perennial grasses in ways that meet their economic goals.
We visualize the following trends in Southern High Plains agriculture in the coming decades in the context of transitioning to low-irrigation management: (1) fewer acres of irrigation overall and increased acres of limited-acreage, high-value crops, (2) continual improvements in water use efficiency of major row crops such as cotton and corn, (3) partial replacement of irrigated row crops with perennial grasses and legumes, water-efficient sorghum and millet crops at low irrigation, and with dryland crops, (4) greater use of precision water management technologies such as ultra-low and variable-rate irrigation, (5) greater dependence on online decision aides for guiding inputs, (6) greater use of cover crops with dual use as forages, and (7) warmer temperatures leading to greater evaporative demand and more droughts. These trends will require constant testing of forage systems across the range of weather conditions experienced to offer options to landowners on how to maintain profitability.
Cooperators
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- - Producer (Educator)
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Research
The final analyses of data from the insect and soil health trials of 2016 and 2017 were accomplished, plus analysis of essential oils in old world bluestem were run in 2018.
The third year of field data were taken in a trial to test the effects of interseeding alfalfa into dryland native grass pastures on forage yield, quality, and competition for soil water. The treatments consisted of high and low density row spacings (14 inch and 28 inch spacings), and three contrasting alfalfa cultivars (two hay types and one grazing type). The first year of new grazing trial was initiated comparing old world bluestem grass growing alone but receiving 60 lbs/acre of N fertilizer per year vs. bluestem growing with interseeded alfalfa but receiving no N fertilizer. Soils were sampled for methane emissions, and enteric methane emissions were measure on grazing steers. This trial will be continued in 2019 and 2020.
Final Years, 2019-2020:
In 2019, the final year of the cattle methane pasture study was completed, and data were analyzed and written up for a PhD dissertation in early 2020 by Kathryn Radicke. Papers were submitted and published from the dissertation works on digital image analysis (Xiong), essential oils in old world bluestem (Bhandari), and alfalfa interseeding into native grass pastures (Dhakal), soil health improvements due to interseeding alfalfa into perennial grass and compared to continuous cotton culture. We also prepared papers for publication on cattle methane production. Other papers were submitted by collaborating colleagues and their students working on low-water-use annual forages serving as alternatives to corn, effect of applying composted cattle manure on soil health indicators, populations of pollinator bees in pastures compared with adjacent cotton fields, soil hydraulic properties of perennial pastures, cover crop effects on soil health, the effect of teff (annual grass) on cattle rumen digestion, and effects of transitioning from high irrigation to low-input irrigation and to dryland on soil health.
Through the Texas Alliance for Water Conservation, our outlet for reaching farmers and farm consultants, we put on three webinars (one on soil health and two on improving pastures with alfalfa) and a fact sheet on improving pastures with alfalfa. My team presented at two field days.
Old World bluestem strongly deterred the deleterious fire ants and harvester ants, even when alfalfa was growing with this grass. This deterrence effect contributes to the resilience of Old World bluestem and to its favorable use as a companion grass with alfalfa. Native grass pastures contained the greatest number of pollinator insects such as native bees, but also contained the most deleterious-type ants. Old World bluestem contained only modestly fewer pollinators than the native grass pastures. Old World bluestem contained essential (volatile) oils that gave off a characteristic aroma in late summer, which have been linked to deterrence of various deleterious insects. The most consistently found oils were acorenone-B, camphene, and naphthalene, which may have caused the deterrence of fire ants. Measurements of microbial and enzyme activities and organic matter content of soil indicated the greatest level of soil health in the mixtures of Old World bluestem and alfalfa, even out-performing monoculture stands of those two forages. Results provide strong evidence of WW-B.Dahl Old World bluestem as a sustainable perennial grass for the water-limited Texas High Plains. Six journal articles were published in 2018 on research pertaining to insects and soil health in relation to forage production and water conservation. Two articles were published in 2019 pertaining to essential oils in bluestem and the role of interseeding alfalfa into bluestem on increasing fungal populations that improve soil quality. This body of work builds on previous work on pasture soil health started by Dr. Vivien Allen in collaboration with Drs. Acosta-Martinez and Moore-Kucera, previous recipients of Southern SARE funding.
An extensive field trial was completed in 2018 on the effects of interseeding alfalfa on the water use, forage yield, and forage quality of nonirrigated native grassland. Results after 3 years showed that alfalfa can survive with native grasses without irrigation on a good soil in west Texas when growing at low density. Widely spaced plantings of alfalfa (28-inch spacing) caused only mild depletion of soil water compared to the non-alfalfa (pure grass) control; whereas the narrowly spaced planting (14 inch) significantly reduced soil water content, indicating excessive competition against the grass for soil water. The higher-density planting of alfalfa thinned down to the lower-density planting within 3 years. The low-density alfalfa substantially increased forage yields of dry matter, protein, and digestible energy over the pure grass control, at only half the seed cost of the dense planting. Results indicate that a well-adapted variety of alfalfa can significantly improve dryland pasture in the Texas High Plains at very low cost without depleting soil water reserves. Four journal papers were accepted for publication in 2019, and a fifth paper will be accepted in 2020.
A short study was undertaken in 2018 as part of the Harrison Hill Jr. Young Scholar Enhancement Grant program (grant LS17-286). Under the supervision of Drs. Lindsey Slaughter and Chuck West, Paxton Hughes measured methane gas exchange between pasture soils and atmosphere in the New Deal pastures. Pastures consisting of Old World bluestem with alfalfa (received no N fertilizer) net-absorbed methane from the atmosphere, whereas bluestem without alfalfa (received N fertilizer) net-emitted methane. Results indicate that interseeding alfalfa into perennial grass pastures grazed by cattle can reduce the net amount of methane emitted from the pasture-livestock system relative to pastures with no legume and obtaining its N from synthetic fertilizer instead of from biological fixation.
In 2018 we initiated a grazing trial comparing two systems, perennial + annual grasses with no legumes but receiving 60 lbs./acre of N fertilizer, and perennial + annual grasses with legumes. The perennial grass was WW-B.Dahl Old World bluestem and the annual was peal millet, growing in separate pastures to allow rotation grazing between the two grass types. The legumes were alfalfa and yellow sweet clover with the bluestem and cowpea with the pearl millet. Cattle gained an average of 2.46 lbs/steer-day on the grass + N system and 2.55 lbs./steer-day on the grass-legume system. Those means were not statistically different, and are both considered quite high for these pastures. Enteric methane production per steer-day did not differ between treatments. This trial was repeated in 2019 and will be summarized in next year’s report. Data analysis will include ratios of methane produced per lb. of forage dry matter intake and ratios of amounts of irrigation water applied per unit of liveweight gain and per unit of methane produced.
Graduate student, Kathryn Radicke, was awarded a graduate student grant (SARE# GS18-196) in late 2018 titled “Effects of cumulative cattle trampling on soil bulk density and infiltration on an annual pasture.” The field tasks were carried out in 2019. She will provide a final report in April, 2020 that includes analysis of the 29019 results.
Final Years, 2019-2020:
Graduate student, Madhav Dhakal, was senior author of a paper from his dissertation that won the 2020 Outstanding Paper Award for the Forage and Grazinglands Division of the Crop Science Society of America. The reference is Dhakal et al. 2019. Crop Science 59:2271-2279. This student published a total of 5 papers in high quality journals enjoying wide readership, a TAWC fact sheet, 4 abstracts at national meetings, and contributed material to 2 webinars and 2 field day presentations. His work on interseeding alfalfa probably had the widest and strongest impact on Southern Plains producers judging by the high attendance in webinars and field days, and questions from producers for more specific information on establishing alfalfa. This partly led the manager of a large beef backgrounding and feeding operation in the Texas Panhandle to approach the TAWC and the TeCSIS research program to help his company offer advice on planting more high-quality perennial forages in their large operation to cut down on feeding expenses and water use.
The general results of the cattle methane trial on pastures were as follows: the inclusion of legumes increased animal liveweight gain in 2018 and 2019 (avg. 402 lbs/ac for alfalfa-grass vs. 314 lbs/ac for N-fertilized grass alone), increased steer daily rate of gain (avg. 2.4 lbs/steer-day vs. 2.1 lbs/steer-day), and reduced water footprint of beef liveweight gain (1511 gallons/lb of gain vs. 1823 gal./lb of gain for grass alone; -17%).
There was no difference in methane emission per head between pasture types in 2018; however, in 2019 there was 13 g/steer-day less methane emission (9.5% decline). The big difference was that dry matter intake by the cattle was 35% greater with alfalfa-grass than with grass alone. The result was that methane emission per pound of forage intake was reduced by 30% by interseeding alfalfa.
This research on water footprint and methane emission also included an economic analysis of these 2 years of cattle production plus 3 of cattle data from the work of earlier student, Lisa Baxter. The 5-year analysis indicated that the inclusion of legumes resulted in overall more profitability per pound of weight gain compared with grass alone. A factor that does limit profitability of including alfalfa with old world bluestem is the somewhat reduced carrying capacity (lower stocking rate) of the former resulting from the absence of N fertilizer.
When considering the broader aspects of sustainability, the high nutritive value of alfalfa suggests a promising future as a valuable forage resource in the Texas High Plains with respect to lowering the footprint of nonrenewable groundwater for grazing cattle production, increasing several parameters of soil health, reducing the negative greenhouse gas impact of cattle grazing forages, reducing costly inputs of N fertilizer, and increasing profit potential.
Graduate student, Kathryn Radicke, reported on her Southern SARE graduate student, performed under the umbrella of this Large Systems project. The field study quantified the effects of heavy stocking density and trampling by cattle on soil compaction and bulk density over time compared to an ungrazed control. Pearl millet was no-till planted in two years. Trampling did not show a significant effect on soil bulk density in the first year. However, heavy rainfall before grazing millet pastures in the second year increased soil bulk density under the same stocking densities by 0.18 g/cm3. Soil bulk density recovered at 270 days after cattle were removed to values similar to the untrampled control. An extended time of nongrazing is likely required for recovery from trampling on a clay-loam soil. Cattle could potentially cause a cumulative increase in soil bulk density in no–till grazing systems, especially when soils at the time of trampling are wet and if a long recovery time is not allowed.
Education
The grazing and related forage research at the Texas Tech New Deal Field Research Station is a Large Systems project for which Southern SARE supports the maintenance and routines supplies for conducting integrated forage-livestock research. We superimpose educational activities on the pasture facilities which include visits by farmers and ranchers, foreign visitors, TTU classes in forage and livestock production, and training of graduate students. In 2018 we hosted 30 agricultural students and instructors from the University of Queensland, Australia, who were touring several universities. These students were here on a course for credit for which they had to write term papers. For that reason, they were highly motivated to ask questions on the management of water, nutrient cycling, greenhouse gases, and other factors related to grassland sustainability. Dr. West's two classes titled Forage and Pasture Crops, and Forages and Livestock Pasture Ecosystems met at the pastures for instructions on plant identification and grazing management. Three graduate students of Dr. West and one graduate student of Dr. L. Slaughter conducted research on the same pastures pertaining to soil health. Dr. Slaughter and Dr. West supervised an undergraduate student to conduct a short research project on methane emission from soil as part of the Southern SARE Young Scholar Enhancement Grant Program. Finally, summaries of the research and demonstration results were included in electronic newsletters that were distributed to 500 subscribers who follow the outreach activities of the Texas Alliance for Water Conservation.
Final report update, 2019-2020: Seven graduate degrees (1 Masters and 6 Doctorates) were earned by graduate students over the course of Phases II and III (under Dr. Chuck West's direction) of the Large Systems project. Two of the doctoral students (Lisa Baxter and Kathryn Radicke) received graduate student grants from SSARE. One doctoral student (Madhav Dhakal) received external funding from a local philanthropic foundation (CH Foundation) to support his assistantship stipend and cost of supplies. Six different undergraduate students worked as part-time labor, some for more than one year. These students learned about the sustainability of grass-based based cattle production at the levels of soil, plant, and animal. Many tours of the pastures were performed for undergraduate students from classes taught by Dr. West and faculty in soil science and animal science. Two undergraduate students conducted special research projects funded by the SSARE Young Scholar Enhancement Program under the direct supervision of collaborator Dr. Lindsey Slaughter.
Educational & Outreach Activities
Invited as the Leu Distinguished Lecturer at the University of Nebraska, Center for Grassland Studies, on sustainable forage-livestock systems with limited resources.
Speaking to community group on reducing water use in beef production, and to individual farmers on agronomic methods of establishing improved pastures and how to use alfalfa to enhance forage quality at low water input.
Co-investigator of a 6-state USDA-NIFA funded project on irrigation efficiency to which I bring in integrated crop-livestock aspects.
Directing undergraduate and graduate students in applied research on grassland soil health and cover crops.
Participation Summary:
Research summaries in the e-newsletter of Texas Alliance for Water Conservation (TAWC).
Farm tours and grazing demonstrations for classes from Texas Tech University and other universities.
Presentations or co-authorships for 8 water conservation conference and 1 grassland conference on the role of forage-livestock systems in conserving irrigation water and adapting to climate change.
Co-advised two undergraduate student on a Southern SARE Young Scholar Enhancement Grant.
The same types of activities are planned for 2019-2020.
Publication citations in 2018 on work related to water conservation in irrigation and in grassland-livestock systems; senior authors noted by * are advisees of Dr. West:
Cano, Amanda, A. Núñez, V. Acosta-Martinez, M. Schipanski, R. Ghimire, C. Rice, and C. West. 2018. Current knowledge and future research directions to link soil health and water conservation in the Ogallala Aquifer region. Geoderma 328:109-118. doi:10.1016/j.geoderma.2018.04.027
*Bhandari, Krishna B., C.P. West, and S.D. Longing. 2018. Fly densities on cattle grazing ‘WW-B.Dahl’ old world bluestem pasture systems. Texas J. Agric. Nat. Res. 31:T1-T5.
*Bhandari, K.B., C.P. West, S.D. Longing, C.P. Brown, and P.E. Green. 2018. Comparison of arthropod communities among different forage types on the Texas High Plains using pitfall traps. Crop Forage Turfgrass Management Vol. 4(2):180005. doi:10.2134/cftm2018.01.0005.
West, C.P., and L.L. Baxter. 2018. Water footprint of beef production on Texas High Plains pasture. Water International 43:887-891. doi:10.1080/02508060.2018.1515574
*Bhandari, K.B., C.P. West, V. Acosta-Martinez, J. Cotton, and A. Cano. 2018. Soil microbial communities, enzyme activities, and total carbon and nitrogen as affected by diverse grasses and grass-alfalfa in pastures. Appl. Soil Ecol. 132:179-186. doi:10.1016/j.apsoil.2018.09.002
*Bhandari, K.B., C.P. West, S.D. Longing, C.P. Brown, P.E. Green, and E. Barkowsky. 2018. Pollinator abundances in semi-arid pastures as affected by forage species. Crop Sci. 58:2665-2671. doi:10.2135/cropsci2018.06.0393
*Bhandari, K.B., C.P. West, and S.D. Longing. 2018. Communities of canopy-dwelling arthropods in response to diverse forages. Agric. Environ. Letters 3(1):180037 (online) doi:10.2134/ael2018.07.0037
Rudnick, D.R., S. Irmak, C.P. West, I. Kisekka, T.H. Marek, J.P. Schneekloth, D.M. McCallister, V. Sharma, K. Djaman, J. Aguilar, J.L. Chávez, M. Schipanski, D.H. Rogers, and A. Schlegel. 2018. Deficit irrigation management of maize above the High Plains Aquifer: A review. J. Am. Water Res. Asso. 55:38-55.
Update 2019-2021: (Asterisks indicate advisees of Dr. West)
Rudnick, D.R., S. Irmak, C.P. West, I. Kisekka, T.H. Marek, J.P. Schneekloth, D.M. McCallister, V. Sharma, K. Djaman, J. Aguilar, J.L. Chávez, M. Schipanski, D.H. Rogers, and A. Schlegel. 2019. Deficit irrigation management of maize above the High Plains Aquifer: A review. J. Am. Water Res. Asso. 55:38-55.
*Xiong, Yedan., C.P. West, C.P. Brown, and P.E. Green. 2019. Digital image analysis of old world bluestem cover to estimate canopy development. Agron. J. 111:1247-1253. doi:10.2134/agronj2018.08.0502
*Dhakal, M., C.P. West, S.K. Deb, G. Kharel, and G.L. Ritchie. 2019. Field calibration of PR2 capacitance probe in Pullman clay-loam soil of Southern High Plains. Agrosyst. Geosci. Environ. 2:1-7. doi:10.2134/age2018.10.0043
*Bhandari, K.B., C.P. West, D. Klein, and S. Subbiah. 2019. Essential oil composition of ‘WW-B.Dahl’ old world bluestem [Bothriochloa bladhii] grown in the Texas High Plains. Industrial Crops Products 133:1-9. doi:10.1016/j.indcrop.2019.03.013
*Dhakal, M., C.P. West, and C. Villalobos. 2019. Establishment and stand development of alfalfa interseeded into native grass mixture: Cultivar and row spacing effects. Crop Sci. 59:2271-2279. doi:10.2135/cropsci2019.03.0156
Bhattarai, Bishwoyog, S. Singh, C.P. West, and R. Saini. 2019. Forage potential of pearl millet and forage sorghum alternates to corn in water limiting condition of Texas High Plains - A review. Crop Forage Turf Management 5:190058. doi:10.2134/cftm2019.08.0058
*Dhakal, M., C.P. West, S.K. Deb, C. Villalobos, and G. Kharel. 2020. Row spacing of alfalfa interseeded into native grass pasture influences soil-plant-water relations. Agron. J. 112:274-287. doi:10.1002/agj2.20012
*Bhandari, Krishna, C.P. West, and V. Acosta-Martinez. 2020. Assessing the role of interseeding alfalfa into grass on improving pasture soil health in semi-arid Texas High Plains. Appl. Soil Ecol. 147: Article 103399. doi:10.1016/j.apsoil.2019.103399
*Dhakal, M., C.P. West, C. Villalobos, C.P. Brown, and P.E. Green. 2020. Interseeding alfalfa into native grassland for enhanced yield and water use efficiency. Agron. J. 112:1931-1942. doi:10.1002/agj2.20147
*Dhakal, Madhav, C.P. West, C. Villalobos, J.O. Sarturi, and D.K. Deb. 2020. Trade-off between nutritive value improvement and crop water use for an alfalfa-grass system. Crop Sci. 60:1711-1723. doi:10.1002/csc2.20159
Bhattarai, B., S. Singh, C. West, G. Ritchie, and C. Trostle. 2020. Water depletion pattern and water use efficiency of forage sorghum, pearl millet, and corn under water limiting condition. Agric. Water Manage. 238: Article 106206. doi:10.1016/j.agwat.2020.106206
Bhattarai, B., S. Singh, C. West, G. Ritchie, and C. Trostle. 2020. Effect of deficit irrigation on physiology and silage yield of BMR forage sorghum, BMR pearl millet, and corn. Crop Sci. 60:2167-2179. doi:10.1002/csc2.20171
Mitchell-McCallister, D.M., A.M. Cano, and C.P. West. 2020. Meta-analysis of water use efficiency in deficit irrigation systems in the Texas High Plains. Irrigation Sci. 38(6): 535–546. doi:10.1007/s00271-020-00696-x
Otuya, R., L.C. Slaughter, C.P. West, S.K. Deb, and V. Acosta-Martinez. 2021. Compost and legume management differently alter soil microbial abundance and soil carbon in semi-arid pastures. Soil Sci. Soc. Am. J. In press.
*Baxter, L.L., C.P. West, C.P. Brown, and P.E. Green. 2021. Cover crops management on the Southern High Plains: Impacts on crop productivity and soil water depletion. Animals 11:212–222. doi:/10.3390/ani11010212
*Bhandari, K.B., S.D. Longing, C.P. West, and C. Lechnar. 2021. Bees and other pollinators in adjacent Old World bluestem and cotton fields in the Texas High Plains. Texas J. Agric. Sci. Nat. Resour. 34:1–9.
*Bhandari, K.B., and C.P. West. 2021. Differences in soil microbial communities in dryland forage production systems in semi-arid Texas High Plains. Texas J. Agric. Nat. Resour. 34:??-?? [In press]
Kharel, G., S.K. Deb, C.P. West, M. Dhakal, L.C. Slaughter, and E. Escamilla. 2021. Long-term pasture management influences soil hydraulic and thermal properties. Geoderma [In revision]
Wang, Jun, S. Zhang, U.M. Sainju, R. Ghimire, F.Zhao, and C. West. 2021. Is cover cropping sustainable? A meta-analysis of soil water storage and succeeding cash crop yield. Agric. Ecosyst. Environ. [Submitted]
Sugg, J. D., J. O. Sarturi, D. D. Henry, F. M. Ciriaco, C. P. West, M. A. Ballou, and C. A. Hoffmann. 2021. Ruminal degradation kinetics, intake, digestibility, and feeding behavior of beef steers fed annual or perennial grass-hay with or without supplementation. J. Anim. Sci. [Submitted]
Learning Outcomes
Significant interest in how to transition from monoculture cropping to diversified crop-forage-livestock systems as a means of coping with the reduction of the Ogallala Aquifer.
Conversion of formerly irrigated row cropland to perennial grasses for grazing
Improving dryland forage yield and quality by interseeding alfalfa into grasslands
Management of reduced irrigation use on forages
Project Outcomes
Over the entire history of this project since an initial SARE grant in 1997, the amount of information and student education, thesis, field days, instructional videos, handouts, presentations, and journal articles has been enormous and indicates the potential return on investment in long-term research and education. The research output and education events at the New Deal research farm tie into broad-scale efforts to disseminate scientifically tested advances in water use, soil management, and integration of crops and livestock in an environment where the main driver of farm profitability and rural economy has been the Ogallala Aquifer, now in decline. These broader efforts include the TAWC, which directly impacts landowners and decision-makers, commercial companies dealing with crop consulting, irrigation equipment, and improved cultivars, collaboration with other institutions with complementary missions such as USDA-NRCS, and finally the greater mission of Texas Tech University in educating students and visitors on land and water sustainability. These efforts demonstrate that the support of research infrastructure at the Texas Tech New Deal Research Station has been leveraged to amplify the transfer of sustainable agricultural technology in the Southern High Plains.
In the 2017 annual report, the significant finding was reported that a 3-year grazing trial analyzed by Lisa Baxter showed greater stocker steer liveweight gains when grazing a pasture rotation system that contained alfalfa compared to grazing grass only, and that the grass-legume system resulted in a lower water footprint for beef liveweight gain; all this with only 7-8 inches (average) of irrigation. These results were the core messages of two symposium talks that Dr. Chuck West was invited to give in 2018 on sustainable beef cattle systems, 1) annual meeting of the American Society of Animal Science, and 2) Leu Distinguished Lecture Series at the Center for Grassland Studies at the University of Nebraska. The current grazing trial (2018-2020) follows up on the relationship between legume presence and efficient was use. Other studies by graduate students Krishna Bhandari, Madhav Dhakal, and Yedan Xiong deepened our knowledge on insects, soil health, drought tolerance of Old World bluestem, and the strong role that alfalfa can play in enhancing forage yield and quality and cattle productivity at very low water input and without nitrogen fertilization. Collaboration with Dr. Lindsey Slaughter, soil microbial ecologist, has expanded our study of greenhouse gas emissions from soil. Collaboration with Dr. Darren Henry, ruminant nutritionist, opened up the technology for measuring enteric methane emissions from grazing cattle. Collaboration continued with Dr. Sanjit Deb on soil physics and hydrology to better understand how water moves and is stored in these pasture soils. These collaborations enable us to integrate more thoroughly the aspects of water, nitrogen, and carbon cycling at the soil, plant and animal levels so that efficiency of all resources are maximizing in the fragile environment of the Texas High Plains.
WW-B.Dahl old world bluestem is the best perennial grass forage to grazing by beef cattle because of its low water needs, persistence, deterrence of harmful insects (e.g. fire ants), tolerance to continuous grazing, flexibility in use for grazing, stockpiling, and hay, and its good nutritional quality. Plus, it is compatible with alfalfa in mixture.
Alfalfa is the most productive and reliable legume to use in forage systems in the Texas High Plains thanks to its extremely high nutritional quality, persistence with moderate to low irrigation input, compatibility with old world bluestem and rainfed native grasses, and deep roots to extracting water. Alfalfa has excellent potential as a low cost (with low seeding rate) addition to rangeland having appropriate soils to improve forage yield and quality without causing significant additional soil water extraction.