VTechWorks Repository :: Browsing by Author "Thompson, Thomas L."

Browsing by Author "Thompson, Thomas L."

Now showing 1 - 19 of 19

2020 Global Agricultural Productivity Report: Productivity in a Time of Pandemics
Steensland, Ann; Thompson, Thomas L. (Virginia Tech College of Agriculture and Life Sciences Global Programs, 2020-10-12)
Agricultural communities battle pandemic-scale pest and disease outbreaks every year. The health and productivity of people, livestock, and crops are all vulnerable. Food and nutrition security, livelihoods, and environmental sustainability are all threatened by these outbreaks. The Global Agricultural Productivity Report lays out some of pandemic scale threats that must be addressed to ensure that we can sustainably produce food, feed, fiber, and bioenergy for 10 billion people in 2050. Agricultural productivity is not just essential for sustainably meeting the demands of a growing world. The technologies and practices that increase productivity can also be harnessed to cultivate resilience, especially to pandemics that can strike with little warning, with catastrophic results.
Assessing Potential Solutions to Mitigate Pollution from Neonicotinoid Seed Coatings
Morrison, Benjamin Anthony (Virginia Tech, 2020-12-08)
Thiamethoxam and clothianidin are two neonicotinoids used in seed coatings for crops such as corn and soybeans. Both neonicotinoids have high solubility in water, so they are prone to transport via leaching and runoff. This thesis is comprised of two studies that evaluated potential solutions to mitigate neonicotinoid transport from fields. The first study examined the relationship between soil organic carbon content and neonicotinoid transport in a field planted in soybeans. Soils with increased organic carbon leached less thiamethoxam and clothianidin during early growing season leaching peaks; however, at the end of the season, higher organic carbon content only decreased leached mass of clothianidin. The second study was to determine neonicotinoid uptake of different ground covers used as cover crops or edge-of-field buffer strips, as well as the partitioning of thiamethoxam and clothianidin throughout the plants. Ground covers, such as crimson clover, had the highest recovery of applied thiamethoxam, meaning that it may be a good candidate to retain this pesticide in fields. Thiamethoxam and clothianidin concentrations were higher in leaf tissues than in stems or roots, indicating that above-ground biomass removal may be an effective way to reduce neonicotinoid loading in the environment. From these studies, I concluded 1) practices that raise the amount of organic carbon in the soil may help decrease early-season neonicotinoid transport, resulting in lower concentrations in surrounding waterways, and 2) careful selection of plant species, such as crimson clover, may help reduce neonicotinoid transport in the environment, while potentially reducing exposure to beneficial insects.
Building resilience in cropping systems of the Central Plateau of Haiti
Thompson, Thomas L.; Kennedy, Nathan; Thomason, Wade E.; Amacher, Gregory S.; Hodges, Steven C. (2013)
This presentation provides information on a project intended to improve resilience through conservation agriculture production systems in the Central Plateau of Haiti. It discusses results from a baseline survey and from agronomic experiments. Analysis includes derivation of Cobb-Douglass production functions based on results from the household survey.
CCRA-9 2014 update
Thompson, Thomas L.; Thomason, Wade E. (2014)
This PowerPoint summarizes the research activities and findings of SANREM’s soil quality and soil carbon sequestration cross-cutting research activity. The presentation describes studies of soil carbon dioxide, GIS agroclimatology comparisons, and density fractionation of soil carbon.
Conservation agriculture in Senegal: comparing the effects of intercropping and mulching on millet yields
Trail, Patrick James (Virginia Tech, 2015-02-25)
Situated on the western edge of Africa's harsh Sahel region, Senegal faces a number of agricultural production constraints. Limited rainfall, poor soil fertility, and insufficient agronomic inputs all contribute to low yielding millet production systems. This study was initiated to assess the potential for intercropping either cowpea (Vigna unguiculata (L.) Walp.) or mungbean (Vigna radiata (L.) Wilczek) into traditional pearl millet (Pennisetum glaucum (L.) R. Br.) cropping systems. During the 2013 and 2014 growing seasons two varieties of cowpea (upright and viney), and one variety of mungbean (upright) were grown in monoculture and subsequently intercropped with millet to evaluate the potential for increasing millet and overall yields. Millet was also planted with a mulch (2 t/ha of neem leaves) to test the effectiveness of increased ground cover on millet yields. In addition to yield data, soil moisture and plant NDVI data were also collected. Millet grain yields increased when intercropped with either cowpea or mungbean compared to millet that was grown alone, with grain yield increases of up to 55%. Additionally, the combined grain yields (millet + bean) were up to 67% higher than the traditional monoculture millet. The addition of mulch was the most effective treatment and increased millet grain yields up to 70%. Soil moisture increased up to 14% in mulched treatments over millet monoculture treatments. All yield increases were achieved without the addition of fertilizers or nutrient amendments. In an attempt to mimic local practices our experiment was rainfed and no soil amendments were introduced.
A conservation agriculture production system program for the central plateau of Haiti
Thomason, Wade E.; Thompson, Thomas L. (2013)
Haiti’s soils suffer from severe degradation as a result of erosion, leading to decreased yields and low food security. The soils of Haiti’s Central Plateau, while less degraded than in other regions, are constrained by lack of water. A conservation agriculture production system can address this by increasing yields, reducing erosion, and improving water use efficiency. This poster provides an overview of the SANREM Innovation Lab program to promote conservation agriculture production system in Haiti’s Central Plateau, and displays the effects of tillage and cover crop treatment on grain yield.
Decomposition, nitrogen and carbon mineralization from food and cover crop residues in the central plateau of Haiti
Lynch, M. J.; Mulvaney, Michael J.; Hodges, Steven C.; Thompson, Thomas L.; Thomason, Wade E. (Springer, 2016-07-04)
Dept. of Crop Soil and Environmental Sciences, Head Lines #24
Thompson, Thomas L. (Virginia Tech, 2015-08-21)
Reflections and updates from the department head of Crop Soil and Environmental Sciences.
Dept. of Crop Soil and Environmental Sciences, Head Lines #25
Thompson, Thomas L. (Virginia Tech, 2016-05-11)
Reflections and updates from the department head of Crop Soil and Environmental Sciences.
Development of a new dual-chamber microlysimeter model for residue decomposition measures
Lynch, M. J.; Thomason, Wade E.; Thompson, Thomas L.; Mulvaney, Michael J. (2013)
This is an abstract from the 2013 American Society of Agronomy Annual Meetings, presented in the second session on General Soil Fertility and Plant Nutrition.
Evaluating Intercropping (Living Cover) and Mulching (Desiccated Cover) Practices for Increasing Millet Yields in Senegal
Abaye, Azenegashe Ozzie; Trail, Patrick; Thomason, Wade E.; Thompson, Thomas L.; Gueye, Fatou; Diedhiou, Ibrahima; Diatta, Michel B.; Faye, Abdoulaye (2016-09-01)
Located within the Sahel region, Senegal faces several agricultural production challenges. Limited rainfall, poor soil fertility, and insufficient agronomic inputs all contribute to low pearl millet [Pennisetum glaucum (L.) R. Br.] yields. This study was initiated to assess the potential for increasing millet yields through intercropping (living cover) and mulching (desiccated cover) practices. During the 2013 and 2014 growing seasons, pearl millet was intercropped with cowpea [Vigna unguiculata (L.) Walp.], mungbean [Vigna radiata (L.) Wilczek], or grown under mulch (neem [Azadirachta indica] leaves applied at 2 t ha–1). Field trials were conducted at two sites within Senegal’s central millet– peanut (Arachis hypogaea L.) basin, in Bambey (14°41¢382 N, 16°28¢122 W) and iés (14°45¢452 N, 16°53¢142 W). Soil moisture and plant N (based on the normalized difference vegetation index [NDVI]) were measured in addition to yield. When inter- cropped with a legume, millet grain yields increased up to 55% compared to millet alone. The combined grain yields under inter-cropping (millet + legume) were always higher than yields of millet alone, up to 67% in Bambey. Mulching increased soil moisture up to 14%, with yield increases of up to 70% over millet with no mulch. Plant N increased in both intercropped and mulched millet, with NDVI increases up to 21% with mulch and 16% when grown with a legume (prior to flowering). These yield increases were achieved using resources that are available and affordable to small-scale producers in the region (seeds and mulch), and did not require the addition of fertilizer input.
Internationalizing the Land Grant Mission: Lessons from Senegal
Abaye, Azenegashe Ozzie; Archibald, Thomas G.; Vaughan, Larry; Thompson, Thomas L.; Thomason, Wade E.; Mbaye, Demba F.; Mamadou, L. O.; Abdoulaye, S.Y.; Gueye, Fatou; Snyder, Glenda; Guiesse, Bineta; Jamison, Kathleen; Vashro, Taylor N. (Virginia Cooperative Extension, 2018-03-20)
Discusses using the land grant university model on an international level, in this case program development in Senegal.
LTRA-6 update 2014
Thompson, Thomas L.; Kennedy, Nathan; Thomason, Wade E.; Amacher, Gregory S.; Hodges, Steven C. (2014)
This PowerPoint summarizes the research and training activities of SANREM’s regional project in the Central Plateau Haiti. The presentation describes a baseline survey conducted at the beginning of the project that discerns smallholder characteristics which drive adoption and reveals existing soil conservation practices. It describes findings from from bean cultivar evaluations, maize cultivar evaluations, studies of maize yields under conservation agriculture, and weed populations under different cover crops. The author concludes that conservation agriculture can be an improved production system in the Central Plateau of Haiti.
A Measurement of Conservation Agriculture’s Effect on Nitrogen and Carbon Mineralization Rates for Agricultural Recommendations in Haiti’s Central Plateau
Lynch, Madalyn Josephine (Virginia Tech, 2015-03-16)
Much of Haitian agriculture is characterized by subsistence farming systems on eroded and nutrient-poor soils. Implementation of Conservation Agriculture systems has proven effective at improving soil quality and crop yield in many areas of the world, including areas similar to those in Haiti. While most Haitian smallholder farmers are highly resource-limited and adoption of new technologies is limited, these farmers are known to adopt new crops and practices if benefits that outweigh risks are demonstrated. Cover crops that help provide soil cover and increase nutrient mineralization are one of the most potentially beneficial changes that could be made on most smallholder farms. However, before specific cover crop recommendations can be made, their potential benefits need to be quantified. One field experiment in the summer of 2013 assessed decomposition rates and nutrient mineralization from common cash crops and two potential cover crops either on the soil surface or buried at 15 cm. The relative difficulty and expense of conducting these types of field trials led to the development and assessment of a laboratory-based system that could be used to simulate plant residue decomposition and nutrient release under controlled conditions. Additional benefits of a laboratory-based study include the ability to test significantly more treatment combinations than would likely be possible under field conditions and to control nearly all other experimental variables, other than the desired treatment comparisons.
Mungbean [Vigna radiata (L.) Wilczek]: Protein-rich Legume for Improving Soil Fertility and Diversifying Cropping Systems
Diatta, Andre Amakobo (Virginia Tech, 2020-04-21)
Drought, salinity, and low soil fertility have negative impacts on agricultural productivity, resulting in food scarcity and nutritional insecurity, particularly in Sub-Saharan Africa. Mungbean [Vigna radiata (L.) R. Wilczek] has seen increased interest as a short-duration and drought tolerant legume crop, capable of atmospheric N₂ fixation. Mungbean is a protein and iron-rich legume and can be used as vegetable or grain for human consumption or multipurpose crop. At present, few studies have simultaneously explored the best agronomic practices for mungbean cultivation and evaluated its potential for increasing crop yields via intercropping systems and improving soil fertility through biological N₂ fixation. To understand the agronomic practices and soil physical properties limiting mungbean production, the impacts of two mungbean cultivars (Berken and OK2000) with and without inoculation with Bradyrhizobium spp. grown in loamy sand and silt loam soils on mungbean growth and yield were investigated under glasshouse conditions. Promising results from this study led to the introduction of mungbean into pearl millet systems in Senegal and evaluation of the effects of intercropping on growth, yields, land equivalent ratio (LER), canopy cover estimates, and normalized difference vegetation index (NDVI). Finally, we evaluated plant growth and N₂ fixation of five mungbean genotypes grown in two soil textures using the ¹⁵N natural abundance technique leading to recommendations for those with the greatest overall benefit to the cropping system. The literature review shows mungbean often proposed as a strategic crop for increasing legume diversification within current cropping systems and providing increased food security as well as market diversification and economic sustainability. The greenhouse study revealed that OK2000 cultivar produced significantly higher yield when inoculated and planted on a silt loam soil than other treatments, indicating the importance of inoculation and soil texture in mungbean establishment. Intercropping mungbean and millet significantly (p≤ 0.05) increased combined yields (35% to 100% increase) and LER compared to sole millet cropping systems. Canopy cover estimates and NDVI values significantly increased up to 60% and 30%, respectively, in millet-mungbean intercropping over millet alone. The N2 fixation study showed that %Ndfa of mungbean was higher when grown in the loamy sand soil (27% increase). However, soil N uptake (235 mg plant⁻¹) and amount of N fixed (67 mg plant⁻¹) were greater in the silt loam soil. Among genotypes, IC 8972-1 significantly (p≤ 0.05) derived less N from the atmosphere (23%) but took more soil N (155 mg plant⁻¹) which yielded significantly greater dry biomass (7.85 g plant⁻¹) and shoot N content (200 mg plant⁻¹). The results from the N₂ fixation study indicated that choice of mungbean genotype can contribute to reducing N needs of agricultural systems. Overall, this research project demonstrated that mungbean has the potential for diversifying smallholder agriculture and adding biologically fixed N into soils, in line with transformative adaptation strategies being promoted for sustainable agriculture. Further research and development programs on good cultural practices, adaptation to cropping systems, and nutritional benefits for human consumption can promote mungbean cultivation in SSA.
Pearl Millet Nutritional Quality and Fertilization of Sweet Corn in Senegal
Drame, Marieme (Virginia Tech, 2016-06-25)
Agricultural production is the main source of income and major employer in many countries in Africa, including Senegal. Commercial sweet corn (Zea mays L. ssp. saccharata) production in Senegal is increasing in response to global marketing opportunities and offers producers the ability to increase income and diversify the cropping base. Production of optimum sweet corn yield and quality depends on adequate nutrient supply, particularly, nitrogen (N). Current N recommendations are based on recommendations specific to corn for grain. This study aimed to identify tools to estimate sweet corn N status and determine the most appropriate fertilizer dosage for sweet corn. Non-destructive remote sensing tools and ion exchange resin membranes (IEMs) were used to evaluate the effect of fertilizer dose. No differences in ear yield or yield components, normalized difference vegetation index (NDVI) values, biomass, N uptake or leaf N concentration due to fertilizer dose were detected at Ndiol. However, significant relationships existed between NDVI values and yield, biomass, and N uptake at the V9 growth stage. Only yield was affected by fertilizer dose at Sangalkam, and no consistent relationships were found between chlorophyll meter readings and others measured parameters. Treatment differences due to fertilizer dose for available NH4+ at V9 (Ndiol), and NO3- at V5 (Sangalkam) were found, however further research is needed to fully evaluate the usefulness of IEMs to measure available soil N. Based on these studies, sweet corn fertilizer rates should likely be based on 75% of the dose applied to field corn, however more work is needed to confirm this finding. Pearl millet (Pennisetum glaucum (L) R. Br.) is the most widely grown staple crop in Senegal. Introduction of drought tolerant millet genotypes has helped mitigate the effect of increased water shortage in the region, but little is known about the nutritional composition of these genotypes. Our objective was to compare millet grain nutritional composition among and between putative drought tolerant and drought sensitive pearl millet lines under drought stress and well-watered conditions. One field experiment was conducted in 2014 at the National Center for Agronomic Research (CNRA) of Bambey, Senegal (16°30' and 16° 28' N; 15o44' and 15o42' W). The experiment utilized a split-plot design with four replications. Water regime was the main plot experimental factor while genotype, a total of 20 was the sub-plot. Pearl millet genotypes were divided into three contrasting groups based on drought tolerance for comparisons. Water stress did not affect 100-grain weight, test weight, protein, soluble protein, starch, sugars, amino acids or vitamin B2 content of grains among VPD-groups. Accumulation of these constituents of pearl millet grain appear to be genetically controlled and are probably not affected by late drought stress. However, differences were noted among genotypes as the sensitive VPD-group accumulated greater soluble protein, starch and soluble sugars (except sucrose) than the tolerant and medium VPD-groups. The tolerant VPD-group, however, accumulated greater protein and vitamin B2 content. Arginine, proline and serine content was greater in the sensitive VPD-group, while lysine, aspartic acid, and glutamic acid were greater in the tolerant VPD-group. Glycine, histidine, threonine, alanine, tyrosine, valine, methionine, leucine, isoleucine, and phenylalanine were relatively equal in tolerant and sensitive VPD-groups. Calcium and Na levels were affected by water stress in the sensitive VPD-group, but differently. Calcium content was greatest for the sensitive group under drought stress, while sodium was the lowest. Iron accumulation in sensitive VPD-group increased under water stress. Potassium decreased for all VPD-groups under stress, while across water regime, K levels in the drought-sensitive group were lower. Selection for drought appears to effect many of the nutritional constituents of pearl millet grain, however many of these differences appear to be directly related to parameters known to effect plant water relations.
Soil Management for Improved Rice Production in Casamance, Senegal
Fall, Thioro (Virginia Tech, 2016-07-06)
Rice is a staple crop for many countries around the world, and is one of the top three food sources globally. Many environments where rice is grown contain stressors likely to limit its growth and yield. In southern Senegal (Casamance region), rice is mainly cultivated in lowlands near estuaries where drought, salinity, acidity, poor soil fertility, and iron toxicity are the main limiting factors. In Casamance, average rice yield for local farmers is 1 to 2 tons per hectare (809 to 1618 pounds per acre), compared to worldwide average yield of more than 4 tons per hectare. The soil where our 2-year experiment (2014 and 2015) was conducted is highly saline-sodic and acidic, and the salt tolerant cultivar we grew yielded 3.4 tons per hectare in 2013. Our main objective was to increase rice yield. The water table height, salinity, and pH were measured weekly during the rice growing season, and the soil was described, sampled, and analyzed to better understand the water and soil resources. Two planting methods were tested: flat planting and planting on beds. Two soil amendments were compared with each planting method: biochar and crushed oyster shells, alone and in combination. An untreated control was included in the experiment. All plots were fertilized. Treatment effects on soil properties and yield were compared in a split-plot design. Plant tissue was sampled for elemental content. The water table was above the surface and was saline during half of the growing season in 2014, and decreased after rice grain head emerged. Planting methods and amendments did not have an effect on yield in 2014, but biochar amendment increased yield in 2015. In 2014, soil salinity and sodium decreased to below toxic levels late in the growing season in the flat plots but not in the bedded plots. Therefore, flat planting is more appropriate in these lowland rice production systems. Soil pH increased from 4.4 to 7.7 in flat planting where biochar+shell was applied. Soil available nutrients such as P, Mn, and Zn were significantly higher in flat planting compared to beds. Toxic levels of Na (> 2000 milligrams per kilogram) were measured in leaves sampled just before flowering. We recommend flat planting and amending soil with biochar in saline-sodic acid-sulfate paddy soils in Casamance to improve rice yield.
Soil Organic Carbon Isotope Tracing in Sorghum under Ambient CO2 and Free-Air CO2 Enrichment (FACE)
Leavitt, Steven W.; Cheng, Li; Williams, David G.; Brooks, Talbot; Kimball, Bruce A.; Pinter, Paul J.; Wall, Gerard W.; Ottman, Michael J.; Matthias, Allan D.; Paul, Eldor A.; Thompson, Thomas L.; Adam, Neal R. (MDPI, 2022-02-18)
As atmospheric carbon dioxide concentrations, [CO_2Air], continue their uncontrolled rise, the capacity of soils to accumulate or retain carbon is uncertain. Free-air CO₂ enrichment (FACE) experiments have been conducted to better understand the plant, soil and ecosystem response to elevated [CO₂], frequently employing commercial CO₂ that imparts a distinct isotopic signal to the system for tracing carbon. We conducted a FACE experiment in 1998 and 1999, whereby sorghum (C₄ photosynthetic pathway) was grown in four replicates of four treatments using a split-strip plot design: (i) ambient CO₂/ample water (365 μmol mol⁻¹, “Control–Wet”), (ii) ambient CO₂/water stress (“Control–Dry”), (iii) CO₂-enriched (560 μmol mol⁻¹, “FACE–Wet”), and (iv) CO₂-enriched/water stressed (“FACE–Dry”). The stable-carbon isotope composition of the added CO₂ (in FACE treatments) was close to that of free atmosphere background values, so the subsequent similar ¹³C-enriched carbon signal photosynthetically fixed by C₄ sorghum plants could be used to trace the fate of carbon in both FACE and control treatments. Measurement of soil organic carbon content (SOC (%) = g_C/g_{dry soil} × 100%) and δ¹³C at three depths (0–15, 15–30, and 30–60 cm) were made on soils from the beginning and end of the two experimental growing seasons. A progressive ca. 0.5‰–1.0‰ δ¹³C increase in the upper soil SOC in all treatments over the course of the experiment indicated common entry of new sorghum carbon into the SOC pools. The 0–15 cm SOC in FACE treatments was ¹³C-enriched relative to the Control by ca. 1‰, and according to isotopic mass balance, the fraction of the new sorghum-derived SOC in the Control–Wet treatment at the end of the second season was 8.4%, 14.2% in FACE–Wet, 6.5% in Control–Dry, and 14.2% in FACE–Dry. The net SOC enhancement resulting from CO₂ enrichment was therefore 5.8% (or 2.9% y⁻¹ of experiment) under ample water and 7.7% (3.8% y⁻¹ of experiment) under limited water, which matches the pattern of greater aboveground biomass increase with elevated [CO_2Air] under the Dry treatment, but no parallel isotopic shifts were found in deeper soils. However, these increased fractions of new carbon in SOC at the end of the experiment do not necessarily mean an increase in total SOC content, because gravimetric measurements of SOC did not reveal a significant increase under elevated [CO_2Air], at least within the limits of SOC-content error bars. Thus, new carbon gains might be offset by pre-experiment carbon losses. The results demonstrate successful isotopic tracing of carbon from plants to soils in this sorghum FACE experiment showing differences between FACE and Control treatments, which suggest more dynamic cycling of SOC under elevated [CO_2Air] than in the Control treatment.
Temporal Nutrient Dynamics in Cool-Season Pasture
Jones, Gordon B. (Virginia Tech, 2013-06-04)
Understanding the nutrient dynamics of pastures is essential to their profitable and sustainable management. Tall fescue [Schendonorus phoenix (Scop.) Holub.] is the predominant forage species in Virginia pasturelands. Although tall fescue pasture is common, little research has attempted to document how soil and herbage nutrient concentrations change through time. This thesis summarizes two studies conducted within the context of a larger grazing systems project near Steele's Tavern, VA. The objectives were to: (1) examine temporal changes in plant available soil nutrient concentrations in four grazing systems, (2) determine how hay feeding and use of improved forages affected soil and herbage nutrient concentrations (3) examine the relationship between and variability within soil and herbage nutrient concentrations, (4) analyze the seasonal variation in herbage mineral concentration with regard to beef cattle requirements, and (5) create a statistical model to predict variation in herbage mineral concentration across the growing season. Analysis of plant and soil nutrients through 5 years of grazing produced several important findings. Soil pH, P, and Ca, Mg, and B declined through five years of grazing. Higher concentrations of herbage N and K and soil P, K, Fe, Zn, and Cu were measured in hay feeding paddocks. Herbage nutrient concentrations showed less variability in P and K than did soil test results. Fertility testing in pastures is important to monitor changing nutrient concentrations, and this study showed that herbage analysis may provide a more stable and accurate assessment of pasture fertility than soil testing. Pasture herbage, grown without fertilization, contained sufficient concentrations of macronutrients to meet the requirements of dry beef cows through the growing season and to meet the requirements of lactating beef cows in April. A model was developed using soil moisture and relative humidity that predicted (R2 = 0.75) variation in herbage mineral concentration throughout the growing season. As described in this thesis, use of modeling to predict nutrient dynamics in pasture could allow for more efficient mineral supplementation strategies that lead to improved profitability, nutrient retention, and livestock health.

Browsing by Author "Thompson, Thomas L."

Results Per Page

Sort Options