Christopher W. Rogers

Methane emissions from drill-seeded, delayed-flood rice production on a silt-loam soil in arkansas.

Rice ( L.) production is unique among staple food crops because the majority of the growing season typically occurs under flooded-soil conditions. Flooding the soil leads to anaerobic conditions, which are a precursor to methane (CH) production. However, no known research has investigated CH emissions from the drill-seeded, delayed-flood rice production system common in Arkansas, the leading rice-producing state in the United States. Therefore, research was conducted in 2011 to determine the effects of vegetation (rice and bare soil), chamber location (in- and between-rice rows), and nitrogen (N) fertilization (optimal and no N) on CH emissions from a silt-loam soil. Methane fluxes measured weekly from flooding until flood release were affected by vegetation, chamber location, and sample date ( < 0.05). In-row CH fluxes were <0.7 mg CH-C m h until 20 d after flooding (DAF) and <1.0 mg CH-C m h from between-row and bare soil until 41 DAF and were unaffected by fertilization over time. The largest weekly measured CH flux (31.9 mg CH-C m h) was observed from in-row rice at 41 DAF. Post-flood-release CH fluxes were affected by vegetation, fertilization, chamber placement, and sample date ( < 0.05) and accounted for approximately 3 to 7% of the season-long CH emissions. Methane emissions averaged 195 kg CH-C ha per growing season and were unaffected by fertilization. Direct measurement of CH emissions from drill-seeded, delayed-flood rice grown on a silt-loam soil will improve the accuracy of assessments of the carbon footprint and long-term sustainability of rice.

Cultivar and Previous Crop Effects on Methane Emissions From Drill-Seeded, Delayed-Flood Rice Production on a Silt-Loam Soil

Abstract The effects of cultural practices on drill-seeded delayed-flood rice (Oryza sativa L.) production on methane (CH4) emissions are not well quantified. In Arkansas, rice is produced predominantly on loamy soils following soybean (Glycine max L.) as the previous crop, and hybrid rice has replaced a large percentage of pure-line cultivars in the past decade. Therefore, research was conducted during the 2012 growing season to assess the effects of previous crop (rice or soybean) and cultivar (standard-stature, semi-dwarf, and hybrid) on CH4 emissions on a silt-loam soil. A 30-cm-diameter chamber-based method was used to determine fluxes during the 2012 growing season. When soybean was the previous crop, fluxes were generally lower (P < 0.05) until heading, after which all fluxes decreased until flood release. Seasonal emissions differed based on previous crop and cultivar (P < 0.05). Area- and yield-scaled growing season emissions from rice following soybean were less (127 kg CH4-C ha−1; 13.7 kg CH4-C (mg grain)−1) than when rice followed rice (184 kg CH4-C ha−1; 20.5 kg CH4-C (mg grain)−1). Hybrid rice emitted less (111 kg CH4-C ha−1; 11.1 kg CH4-C (mg grain)−1) than semi-dwarf (169 CH4-C ha−1; 18.3 kg CH4-C (mg grain)−1) or standard-stature rice (186 kg CH4-C ha−1; 21.9 kg CH4-C (mg grain)−1), which did not differ. Thus, results indicated decreased emissions when soybean was the previous crop and when the hybrid cultivar was grown. The incorporation of factors known to influence CH4 emissions (i.e., previous crop, cultivar, and yield) will improve estimates of the carbon footprint of rice.

Previous Crop and Cultivar Effects on Methane Emissions from Drill-Seeded, Delayed-Flood Rice Grown on a Clay Soil

Due to anaerobic conditions that develop in soils under flooded-rice (Oryza sativa L.) production, along with the global extent of rice production, it is estimated that rice cultivation is responsible for 11% of global anthropogenic methane (CH4) emissions. In order to adequately estimate CH4 emissions, it is important to include data representing the range of environmental, climatic, and cultural factors occurring in rice production, particularly from Arkansas, the leading rice-producing state in the US, and from clay soils. The objective of this study was to determine the effects of previous crop (i.e., rice or soybean (Glycine max L.)) and cultivar (i.e., Cheniere (pure-line, semidwarf), CLXL745 (hybrid), and Taggart (pure-line, standard-stature)) on CH4 fluxes and emissions from rice grown on a Sharkey clay (very-fine, smectitic, thermic Chromic Epiaquerts) in eastern Arkansas. Rice following rice as a previous crop generally had greater () fluxes than rice following soybean, resulting in growing season emissions () of 19.6 and 7.0 kg CH4-C ha−1, respectively. The resulting emissions from CLXL745 (10.2 kg CH4-C ha−1) were less () than those from Cheniere or Taggart (15.5 and 14.2 kg CH4-C ha−1, resp.), which did not differ. Results of this study indicate that common Arkansas practices, such as growing rice in rotation with soybean and planting hybrid cultivars, may result in reduced CH4 emissions relative to continuous rice rotations and pure-line cultivars, respectively.

Nitrogen Source Effects on Methane Emissions From Drill-Seeded, Delayed-Flood Rice Production

ABSTRACT Rice (Oryza sativa L.) cultivation is unique compared with the production of most other upland row crops in that rice is typically produced under flooded-soil conditions, which can result in net emissions of methane (CH4). Nutrient applications for optimum production, specifically nitrogen (N), which can be organic or inorganic sources, are carefully managed in rice production. However, how nutrient-source effects on CH4 emissions from rice production may interact with other known factors affecting CH4 emissions, such as previous crop/crop rotation and soil texture, are poorly understood, particularly in the midsouthern United States where rice production is concentrated. The objective of this study was to evaluate CH4 fluxes and season-long emissions as affected by fertilizer-N source (i.e., ammonium sulfate [AS], pelletized poultry litter [PPL] + urea, and urea only) and previous crop in rotation (i.e., soybean [Glycine max L.] or rice) from rice production on a clayey Epiaquert and a silt-loam Albaqualf in the Lower Mississippi River Delta region of eastern Arkansas. Methane fluxes, measured using 30-cm-diameter, enclosed-headspace chambers, peaked near heading for all treatments, with PPL + urea resulting in greater (P < 0.05) peak fluxes than for the other fertilizer-N sources from both soil textures. Methane fluxes were consistently numerically lower from the clay soil throughout the growing season than from the silt-loam soil. Methane emissions from AS were, on average, 21% lower (P < 0.05) than from PPL + urea or urea only, which did not differ, from the silt-loam soil. Methane emissions were 60% lower (P < 0.05) when soybean was the previous crop compared with rice on the clay soil, but were unaffected (P > 0.05) by previous crop on the silt-loam soil. Results clearly indicate that the choice of fertilizer-N source for certain soil textures, specifically AS application to a silt-loam soil, has the potential to mitigate CH4 emissions and reduce the large, negatively perceived, C footprint associated with rice production.

Sugar beet wireworm Limonius californicus damage to wheat and barley: evaluations of plant damage with respect to soil media, seeding depth, and diatomaceous earth application

Wireworms, the larval stage of click beetles (Coleoptera: Elateridae), continue to be one of the major concerns of cereal producers, primarily due to the lack of effective pesticides and species-specific management options. To have a better understanding of species-specific interactions of one of the most damaging wireworms in the Pacific Northwest and intermountain regions of the USA, a greenhouse study was set to evaluate the damage from the sugar beet wireworm Limonius californicus to wheat and barley planted at different depths and in soil media with varying levels of organic content and texture. Overall, the evaluated wheat appeared to be more susceptible than the barley, showing greater reductions in emergence success and foliar biomass. The greatest loss of foliar biomass was observed in peatmoss-dominated medium, as indicated by a significant host plant-by-soil media interaction. Percentage of plants fed upon by L. californicus was significantly higher in the sand-dominated medium than peatmoss-dominated and 1:1 mix media. Moreover, manipulation of soil media by the addition of diatomaceous earth showed no consistent effect in protecting the planted wheat. Our findings indicated that in addition to quantifying wireworm species-specific interactions, host plant interactions with the environment in the presence of wireworm infestation should also be further studied. These relationships could influence the outcome of integrated management approaches and future risk assessment models and recovery plans.

Grain Yield, Quality, and Nutrient Concentrations of Feed, Food, and Malt Barley

ABSTRACT Barley (Hordeum vulgare L.) is a cereal grown for animal feed, human consumption, and malting. Nutrient concentrations are important as they provide information regarding the dietary values of barley consumed by animals or human beings. In addition, grain nutrient removal may be useful for refining fertilizer recommendations. A study was conducted in 2015 and 2016 investigating the cultivar effects on grain yield, quality, and grain nutrient concentrations and removal under irrigated conditions for two-row barley cultivars. Adjunct and feed cultivars produced the highest yields compared with the all-malt and food cultivars. Specific quality and nutrient values were greater than or equal to in the food cultivar compared to the malt or feed cultivars. Variations in nutrient concentrations were measured among the adjunct and all-malt cultivars, which could potentially affect the malting and brewing qualities. Grain yield, quality, nutrient concentrations and nutrient removal varied among cultivars grown under identical environmental conditions, which may influence end-use.

Evaluation of Ammonia Recovery from a Laboratory Static Diffusion Chamber System

ABSTRACT Ammoniacal fertilizers are susceptible to ammonia (NH3) volatilization, and multiple methods have been introduced to quantify loss. Methods to quantify differences in NH3 loss are important for evaluating the effectiveness of treatments. Recent research hypothesized that opening chamber enclosures resulted in nitrogen (N) loss (16–30%). Thus, the recovery efficiency of static diffusion chambers used in laboratory experiments was investigated. Chambers with a sand–calcium carbonate (CaCO3) mixture received ammonium-N (NH4-N) solutions. Three time intervals were used to determine if variation in enclosure opening influenced recovery. Acid trap percent recovery and a mass balance approach were used. No differences in cumulative NH3 volatilization were measured from either acid traps or using a mass balance approach. No differences were measured in percent recovery based on N application rate, sample interval, or their interaction, and mean percent N recovery was 99.0%. Thus, diffusion chambers can be reliably used to measure differences in NH3 volatilization.

Managing Agricultural Greenhouse Gases: Coordinated Agricultural Research through GRACEnet to Address Our Changing Climate.

1820 An understanding of greenhouse gases (GHGs) associated with agricultural production is a key area of interest in the current scientiic literature due to the potentially negative inluence of agricultural GHGs associated with global climate change. Managing Agricultural Greenhouse Gases focuses on the national GRACEnet project initiated by the USDA–ARS in 2002 and provides a current summary of the research and “state of science,” as described by the authors, resulting from the coordinated research eforts at more than 30 USDA–ARS locations. hese scientists and USDA–ARS locations are widely distributed across the continental United States and thus provide a wide array of information obtained from varied agricultural systems. he book is divided into seven sections, providing extensive information on a wide range of topics ranging from the impacts of no-till crop production in the eastern United States to national economic policy considerations. Section 1 provides supporting details that establish the context for the remainder of the text. he authors provide background information establishing the basis for concerns of anthropogenic GHG emissions, particularly as related to agriculture. Sections 2 and 3 are largely focused on investigating speciic regions in the United States (eastern, central, and western) with a focus on soil organic C dynamics and carbon dioxide, methane, and nitrous oxide response to management, respectively. his organization allows the reader to rapidly access information associated with speciic regional concerns and agricultural production systems in the United States. Section 4 provides detailed reviews of ive models used for estimating soil organic C dynamics and GHG lux, which gives the reader the opportunity to easily compare models. Section 5 details methodology used by GRACEnet scientists for measuring and monitoring agricultural GHGs and discusses Managing Agricultural Greenhouse Gases: Coordinated Agricultural Research through GRACEnet to Address Our Changing Climate