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Enhancing crop diversification is needed to ensure sustainable food and energy production in the soybean [Glycine max (L.) Merr.] and maize (Zea mays L.) dominated cropping systems of the US Midwest. Relay‐cropping soybean with winter camelina [Camelina sativa (L.) Crantz] is a means to sustainably intensify food and energy production while adding cropping system diversity. However, soybean yields in relay systems tend to be less than a full‐season monocrop. We hypothesized that improved soybean selection and seeding date for relay cropping could minimize this yield gap, thus increasing agricultural land use productivity. A 2‐year field study was conducted to determine the effects of soybean maturity and seeding date (SD) on winter camelina and soybean yields and land use productivity. Three soybean genotypes differing in maturity (MG) were relayed into winter camelina at rosette (SD1), bolting (SD2), and first flowering (SD3) growth stages. The soybean MGs were MG0.2, MG1.1, and MG1.7 representing early, standard, and late maturity, respectively, for the study region. The MG1.1 sown at SD2 was grown as sole crop check using conventional practices (CP). Results demonstrated that SD3 decreased camelina seed yield compared with SD1 and SD2. Soybean yield in the relay system was greatest for the MG1.7 genotype, and averaged across SD1 and SD2, was just 11.6% less than the sole crop CP check. Relaying soybean MG1.7 at SD2 produced 43% greater total (camelina +soybean) oil yield and greatly improved land use efficiency compared with CP. Appropriate soybean genotype selection can enhance winter camelina–soybean relay system productivity and land use efficiency.

Ascochyta blight (AB), caused by the pathogen Ascochyta rabiei, is a major threat to chickpea production worldwide, causing major yield losses and decreasing quality. Control of AB requires integrating pest management options including resistant cultivars and fungicide applications. To address this, fungicides with different modes of action were evaluated on three chickpea cultivars with differing levels of susceptibility to AB under irrigated and dryland conditions in 2015 to 2017. The fungicides were applied once or twice and compared with a no-fungicide application control on AB score and yield. The mean grain yields across locations and years were 1,753, 1,283, and 981 kg/ha, with a corresponding AB mean score of 2.6, 3.2, and 3.3 on 0 to 7 scale (where 0 is no disease and 7 is completely dead) for the moderately resistant, moderately susceptible, and susceptible chickpea cultivars, respectively. Fungicide application was not enough to control disease throughout the season. The use of AB-resistant cultivars had the most significant impact on minimizing the disease and maximizing yield, irrespective of year and location. This study supports previous research indicating that planting AB-resistant chickpea cultivars is essential for disease control, regardless of the fungicides applied.

Dry pea (Pisum sativum L.) is an important crop in the Northern Great Plains of the USA and Canada. Information on dry pea quality as affected by cultivars and environments is limited. This experiment determined the effects of dry pea cultivars and environments on protein, starch, and ash concentrations. Six dry pea cultivars (‘Arcadia’, ‘Bridger’, ‘CDC Striker’, ‘Cruiser’, ‘Montech 4152’, and ‘SW Midas’) were evaluated in a randomized complete block design with four replications in 22 environments. The results showed that cultivar × environment interaction effects were highly significant on protein, starch, and ash concentration (p −1 seed for protein, 439 to 617 g kg−1 seed for starch, and 10.5 to 31.9 g kg−1 seed for ash. The differences among environmental means were substantial compared with cultivar means. When averaged over environments, ‘CDC Striker’, ‘Arcadia’, and ‘Montech 4152’ produced greater mean protein, starch, and ash concentrations, respectively, than the other cultivars. None of these cultivars simultaneously outperformed the others for protein, starch, and ash concentrations. This may indicate the need to develop cultivars with outstanding qualities across environments to receive satisfy premium end-user quality requirements.

Introducing cover crops is a form of ecological intensification that can potentially reduce local, regional and global environmental impacts of soybean cropping systems. An assessment of multiple environmental impacts (global warming potential, eutrophication, soil erosion and soil organic carbon variation) was performed on a continuous soybean system in the U.S. upper Midwest. Four sequences were assessed and compared: a soybean cropping system with winter camelina, field pennycress, or winter rye as cover crop, plus a control (sole soybean). Cover crops were interseeded into standing soybean in Year 1, while in Year 2 soybean was relay-cropped into standing camelina or pennycress. Rye was terminated before sowing soybean. When compared with the control, sequences with cover crops showed lower eutrophication potential (4–9% reduction) and soil erosion (5–32% reduction) per ha year−1, in addition to a lower global warming potential (3–8% reduction) when the cover crop was not fertilized. However, when the economic component was included in the assessment, and the results expressed per USD net margin, the sequences with cover crops significantly reduced their performance in all categories of impact considered. A further optimization of field management for camelina and pennycress is recommended to make the cropping system more sustainable.

The rapid establishment of crop seedlings for competitive resource use is critical for both organic and conventional production systems. Seedling vigor is directly related to a plant's seedling establishment and ability to compete against weeds. Knowledge is lacking on the variation of chickpea (Cicer arietinum L.) seedling vigor traits among the cultivars at early growth stages and how these vigor traits measured in the greenhouse and field correlate to final grain yield. Field and greenhouse studies were conducted to evaluate 23 chickpea cultivars. Nodule numbers per plant, nodule fresh weight, aboveground biomass and shoot height, and vigor index (VI)‐I significantly differed among the commercial chickpea varieties and breeding lines in the greenhouse study. Aboveground and belowground biomass, N uptake, and VI‐II also showed significant differences among the cultivars in the field study in 2017. The greenhouse‐measured parameters did not correlate well with field measurements, except for VI‐I and field‐measured biomass. Although chickpea seed yield in 2017 was positively correlated with field‐measured seedling VI‐I and VI‐II, greenhouse‐measured VI‐I and VI‐II did not correlate with the 2017 seed yield in the field. Although vigorous seedlings enhanced seedling establishment, chickpea seed yield in the field is limited by the availability of plant growth resources such as available water. Smaller‐seeded chickpea cultivars yielded higher under a drier year, and larger‐seeded cultivars performed better in a wetter year.

Reduction of ammonia (NH3) emission in agricultural systems is highly important from agronomic, ecologic, and economic standpoints. We studied NH3 volatilization from surface applied urea and SuperU® (urea containing urease and nitrification inhibitors) and its interaction with tillage system (conventional tillage and no-tillage) in a dryland arable soil. Agronomic efficiency of the fertilizers was also assessed by measuring yield, agronomic N-efficiency, and apparent N-use of camelina (Camelina sativa L.). Results indicated significant variation between the field and laboratory experiments. Due to wet spell around the time of fertilization, cumulative volatilization was significantly lower in the field study. NH3 emission associated with SuperU in the field study was about 45% lower than regular urea, which was attributed to a) activity of urease inhibitor delayed SuperU hydrolysis for about five days and b) a rainfall occurred four days after fertilization that likely carried more fertilizer into the soil from SuperU than urea. In the incubation study, NH3 loss was notable and superiority of SuperU was not seen. The results suggest that just replacing urea with SuperU would not result in mitigation of NH3 emission, but it provides a greater chance for N to enter the soil by one way or another (rainfall in our study). Our results did not show any appreciable interaction between N fertilizers and tillage systems. Application of SuperU in the first year of the study resulted in a significantly higher camelina yield and agronomic N-efficiency, but in the second year, due to unfavorable environmental condition, camelina did not grow well thus did not respond positively to N fertilization. The superiority of SuperU over urea in terms of NH3 volatilization and agronomic efficiency may be achieved if farmers apply the fertilizer timely in accordance with weather conditions.

Genetic and environmental factors lead to a variation in yield and protein content of dry pea (Pisum sativum L.) seeds. The quality of seed, particularly seed vigor, also influences the establishment of crop and thus final grain yield. The area and production for dry peas are increasing in the Northern Great Plains but knowledge is lacking on how the pea lines/varieties differ in the seed vigor at seven leaf stage. This field and greenhouse study evaluated the eight dry pea lines/varieties for seedling vigor indices and correlated them with grain yield and protein concentrations. Significant differences were observed among the lines/varieties for nodule number plant−1 in greenhouse, and grain yield in field conditions. The highest number of nodules plant−1 was obtained with the line MT632, which were at par with lines MT457, and MT190. The highest Vigor Index I was achieved with line MT632 associated with their more shoot lengths as compared to other lines/varieties. The highest Vigor Index II was...

We evaluated the effects of nutrient sources [cattle manure, poultry litter, urea, chemical fertilizers [nitrogen (N), phosphorus (P) and potassium (K)], inter-seeded crimson clover (Trifolium inca...

Winter camelina [Camelina sativa (L.) Crantz] and field pennycress [Thlaspi arvense L.] are oilseed feedstocks that can be employed as winter-hardy cover crops in the current cropping systems in the U.S. upper Midwest. In addition to provide multiple ecosystem services, they can be a further source of income for the farmer. However, using these cover crops is a new agricultural practice that has only been studied recently. The objective of this study was to assess and compare the environmental performance of a maize [Zea mays L.]-soybean [Glycine max (L.) Merr.] cropping system with different winter cover crops - camelina, pennycress, and rye (Secale cereale L.) - in the U.S. upper Midwest. Field experiments were carried out from 2016 to 2017 (2-year maize-soybean sequence) at three locations: Morris (Minnesota), Ames (Iowa), and Prosper (North Dakota). The environmental impact assessment was carried out using a “cradle-to-gate” life cycle assessment methodology. Four impact categories were assessed: global warming potential (GWP), eutrophication, soil erosion, and soil organic carbon (SOC) variation. Two functional units (FU) were selected: (1) 1 ha year−1, and (2) $1 net margin. When expressed with the FU ha yr−1, across the three locations cover crops had (a) lower eutrophication potential and water soil erosion, and (b) lower GWP if the cover crop was not fertilized with nitrogen. Camelina and pennycress were more effective than rye in reducing soil losses, while the three cover crops provided similar results for eutrophication potential. The results for the SOC variation were mixed, but the sequence with rye had the best performance at all locations. When expressed with the FU $ net margin, sequences including camelina and pennycress were overall the worst sequences in mitigating greenhouse gas emissions and nutrient and soil losses. This negative performance was mainly due to the seed yield reduction in the second year of the sequence for both the main cash crop (soybean) and the relayed-cover crop compared with the conventional sequence maize-soybean. Such result led to a lower net margin per hectare in the sequences including camelina and pennycress when compared with the control. The results of this study suggest that the introduction of camelina and pennycress as winter-hardy cover crops has a strong potential for reducing the environmental impacts of the maize-soybean rotation. However, a field management optimization of these cover crops in a relay-cropping system is needed to make them a sustainable agricultural practice.

USA Dry Pea and Lentil Council and Montana Agricultural Experiment Station; Montana Specialty Crop Block Grant Project (Grant no. 12-25-B-1079)

Camelina (Camelina sativa) is a promising biofuel feedstock to fill the fallow period in dryland wheat (Triticum aestivum) −fallow cropping system of the U.S Northern Great Plains (NGP). Responses of camelina to tillage system (conventional tillage [CT] and no-till [NT]), nitrogen (N) rate (0, 45, 90 kg ha−1), and nitrogen source (urea and an enhanced efficiency nitrogen fertilizer [EENF] containing urease and nitrification inhibitors) were evaluated in a 2-yr (2013–2014) field experiment in a dryland farming system of central Montana. Grain yield, biomass, oil content, and oil yield of camelina displayed significant first-order effects of tillage, N rate, and N source when averaged across each of the other factors, but interaction effects were not significant. Camelina tended to yield greater in CT than NT by about 26%. Application of EENF significantly increased grain yield when compared with U, which was more pronounced under CT. Dose response of camelina grain yield, biomass, and grain protein to N rate in the range of 0 to 90 kg ha−1 was linear, whereas N fertilization showed a detrimental effect on oil accumulation in seeds. Although oil content declined in response to N application, oil yield (kg ha−1), which is the most important criterionin seedoil derived biofeedstock, positively responded to N application. Our results clearly demonstrated the need for further research to optimize management strategies for successful camelina production under NT system. Our results also indicated the potential of EENF in enhancing the yield of camelina, especially under CT system. Irrespective of tillage system and source of N, application of 90 kg N ha−1 (minus soil mineral N) led to the highest yield of camelina in this environment, but yield gain in response to N application greater than 45 kg ha−1 was very small.

The Northern Great Plains of the United States and Canada have seen an increase in pulse crops like pea, lentil, and chickpea acreage in dryland and irrigated systems. Rotating pulse crops into cereal crop production systems could reduce the demand for nitrogen fertilizer due to the symbiotic relationship with nitrogen fixing bacteria called diazotrophs. Legume-diazotroph relationships are well studied, but little is known about the free-living bacteria of the bulk soil in the legume-cereal rotation systems. Here we determine the community structure of the overall (16S) and diazotroph (nifH) soil microbiome in pulse-cereal rotations across the state of Montana. Many variables influenced the microbial community structure, but and among them, irrigation caused a significant shift in the composition of the communities and co-occurrence network topology. Interestingly, the diazotrophic communities in dryland soil are more robust and contain more generalist compared to irrigated soils. Co-occurrence networks support the identification of different diazotrophic keystone taxa such as Firmicutes in irrigated and Proteobacteria in dryland soils. Linking farm management practices and crop productivity with microbial community structure dynamics is an initial step in establishing a knowledge base for farmers to exploit the soil microbiota to maintain healthy soil for crop production.

Despite the great potential of camelina ( Camelina sativa L. Crantz) as a promising biofuel feedstock, in-farm energy flow of the crop and its associated environmental impacts has not received sufficient attention from researchers. In order to assess net energy gain and to identify energy saving and environmental friendly production operations, a two year study was conducted at central Montana. We investigated the effects of tillage method (CT (conventional tillage) vs. NT (no-tillage)) and N (nitrogen) fertilizer rate (0, 45, 90 kg N ha −1 ) on energy balance and GHG (greenhouse gas emission) of dryland camelina production. Results indicated that energy input and GHG emission were 5 and 8% lower in NT than in CT. Application of 45 and 90 kg N ha −1 increased camelina energy input by 186 and 365%, while increased energy output by only 21 and 64%, respectively. There was no significant difference in net energy gain in response to N fertilization, but lower energy efficiency in response to higher N inputs. Averaged across tillage systems, the GHG emission was 32.0 kg C eq ha −1 with 0 N applied, and the GHG emission increased by 206 and 389% when 45 and 90 kg N ha −1 was applied. Overall, N fertilizer had the biggest share in total energy input. Averaged over all experimental treatments, 14,945 MJ ha −1 net energy was obtained from camelina crop in this study which shows the potential of this crop as a bioenergy feedstock. Our result showed that implementation of NT is strongly recommendable for camelina production in this region. Moreover, improvement of N use efficiency has the highest priority to improve energy performance and reduce GHG emissions in camelina production.

Improper management of cattle manure and poultry litter from confined animal farming are usually source of water pollution. However, appropriate application of these products on switchgrass ( Panicum virgatum L.) field can enhance biomass yield and promote nutrient recycling. We evaluated the effects of harvest frequency and nutrient sources on yield and quality of switchgrass for biofuel feedstock. The experiment was carried out at Perkins and Lake Carl Blackwell, Oklahoma, from 2009 to 2011 using split plot design with four replications. The main plot treatments were two harvest frequencies single (June), and twice (June and November). The subplot treatments were nutrient sources: 1) cattle manure (CM), 2) poultry litter (PL), 3) urea (nitrogen at 150 kg ha −1 ), 4) combined chemical fertilizer (nitrogen-P 2 O 5 –K 2 O) with nitrogen at 150 kg ha −1 , P 2 O 5 at 40 kg ha −1 , and K 2 O at 20 kg ha −1 , 5) inter-seeded Crimson clover ( Trifolium incarnatum L.), and 6) control. Mean biomass yield was higher (12.4 Mg ha −1 ) in 2010 than other years possibly due to optimum moisture and temperature in 2010. At Perkins in 2010, application of CM and PL increased biomass yield significantly by 30 and 23% compared with combined chemical fertilizer (12.9 Mg ha −1 ). The effect of nutrient sources on cellulose, hemicellulose and lignin content was not significant at both locations. Cumulative biomass from twice harvest was similar to single harvest except in 2011 due to dry weather after the first cut. The cellulose and lignin content were significantly higher for single harvest compared with twice harvest at both locations.

Semi-arid regions across the world face high potential impacts of climate change, but the risks posed by a changing climate interconnect with a web of related risks and dynamics. The drylands of East Africa, in particular, are crucibles of change in terms of patterns of land and water access and use, natural resource degradation, human development, economic opportunity, social and gender stratification, migration and urbanization. Both risks and the responses to them should therefore be understood as located within a sphere of activity in which adaptation and development merge. The purpose of this paper is to review responses to climate-related social-ecological risks in semi-arid areas of East Africa, in order to lay out an agenda for future critical research. By drawing on a wide range of academic and non-academic sources, the paper maps out the main forms of response to the inter-linked risks in the region, and considers how they might be viewed in terms of a spectrum of development-adaptation actions. In doing so, the discussion highlights key implications of existing and potential responses for people’s livelihoods and wellbeing, particularly in terms of equity and sustainability, and identifies a series of critical questions that need to be posed about response options both within research and practice.

Indoor radiation is a concern for people living in buildings constructed from materials with high emission of radionuclides. In this study, radiation rate measurements of 39 rooms in nine buildings of three different age groups at three locations were made using Electronic Personal Dosimeter (EPD). The measurements included both interiors and exteriors of the rooms. Interior measurements were made in two perpendicular directions from two adjacent walls at distance interval of 0.5 m.  The EPD measurement revealed a decrease in the magnitude of the radiation as the days of measurement progressed, and that necessitated the need of correction factors, which were evaluated using background radiation rates of each location separately. All measured radiation rates were then corrected using the respective correction factors. The results obtained are summarized as follows. Background radiation doses at HU campus and Harar and Dire Dawa towns, averaged over the measurement days is, 4.1, 2.8 and 2.4 mSv/y, respectively. These values reflect effective external doses of 0.82, 0.55 and 0.47 mSv/y, respectively, for the three locations. Dire Dawa old building differed from all the other buildings of the three locations and it exhibited the highest interior radiation of average dose of 0.027±0.011 mSv/y above the background radiation. There were no significant differences between the new and the intermediate buildings of the three locations. When averaged out, irrespective of building ages of each location, HU buildings showed average dose of 0.004±0.004 mSv/y, Harar, -0.008±0.006 mSv/y and Dire Dawa, 0.009±0.008 mSv/y. No difference in radiation rates were observed between the two directions but radiation rates slightly increased from walls to the centers of rooms up to a certain point. Radiation rates of the interior and exterior of each room did not show a significant difference. Though differences were observed among buildings of the three different ages, the differences were not uniform at the three locations. The doses from all the rooms were within the limit set by IAEA for indoor radiation.  Keywords: Background radiation variability; Indoor radiation; Electronic Personal Dosimeter; Radiation rate; Building ageÂ, East African Journal of Sciences, Vol. 10 No. 2 (2016): East African Journal of Sciences Vol (10) No (2)