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The promotion of dry pea ( Pisum sativum L.) and lentil ( Lens culinaris Medik.) production in cereal dominated cropping systems require identifying high yielding and widely adapted genotypes for a diverse range of environments. However, this information is rarely available in the semi-arid temperate region. We carried out two separate experiments consisting of seven genotypes of dry pea in 25 environments and eight genotypes of lentil in 16 environments to determine yield performance and stability. The results showed that environments (E) and genotypes (G) and interaction (G × E) effects were highly significant ( P < 0.0001) for both experiments. Average grain yield among genotypes varied from 2243 to 2680 and from 1229 to 1643 kg ha −1 for dry pea and lentil, respectively. The G × E accounted 5.4 and 15.8% of the total sum of square for dry pea and lentil experiments, respectively. The G × E effects were crossover type for both experiments revealing inconsistent performance of genotypes across environments. Based on interaction principal component analysis of G × E, the dry pea genotypes, Montech 4152 followed by SW Midas and DS Admiral showed combination of better yield performance and stability. Among the lentil genotypes, CDC Richlea followed by Avondale showed less fluctuation to environmental changes but produced similar yields compared with the high yielding lentil genotypes. Therefore, these dry pea and lentil genotypes can be recommended for cultivation in wide range of environments in the temperate semi-arid climates and similar ecologies. [ABSTRACT FROM AUTHOR]

Camelina ( Camelina sativa L. Crantz), as a bioenergy and bio-product feedstock, may be grown as a rotation crop in the wheat-based cropping system to increase land use efficiency in the Northern Great Plains (NGP). In this study, which was conducted from 2008 to 2011 in central Montana, we evaluated the energy balance of three 2-year cop rotational sequences that included camelina-winter wheat ( Triticum aestivum L.) (CAM-WW) and barley ( Hordeum vulgare L.)-winter wheat (BAR-WW) compared with a traditional fallow-winter wheat (FAL-WW) rotation. Results indicated that 52 and 57 % more energy input was invested in CAM-WW and BAR-WW compared to FAL-WW system (9182 MJ ha), respectively. In all rotations, nitrogen fertilizer was the most energy-consuming input and accounted for 76, 68, and 69 % of the total energy used in wheat, barley, and camelina production, respectively. Averaged over 3 years, CAM-WW and BAR-WW systems yielded 34 and 29 % greater gross energy output compared with FAL-WW. The CAM-WW and BAR-WW also outperformed FAL-WW by 30 and 6 % in terms of net energy output. No significant differences in energy efficiency were found between the FAL-WW and CAM-WW systems. Taking into account of the greater net energy as well as similar values of energy use efficiency, the CAM-WW system performed better than the traditional FAL-WW system under rainfed conditions in central Montana. There is a good potential to improve the energy efficiency of the CAM-WW cropping system (by more than 26 %) through refinement of agronomic practices, mainly nitrogen fertilization and herbicide application, which can further enhance the sustainability of camelina feedstock production. [ABSTRACT FROM AUTHOR]

Camelina ( Camelina sativa L. Crantz) is a promising bioenergy crop, but a sustainable production system for this crop has not yet been well developed. There is also concern about competing land use between crop productions for bioenergy or food use. One approach to overcoming this concern and developing sustainable production systems for bioenergy crops is potentially replacing the fallow period in wheat-based cropping systems with bioenergy crops. The agronomic and economic benefits of growing camelina in rotation with winter wheat were evaluated in a replicated rotation study from 2008 to 2011 in the Northern Great Plains (NGP), focusing on the effects on wheat yield and overall profitability of the cropping system. Average winter wheat yields were 2401 and 1858 kg ha −1 following camelina and barley, respectively, representing a 13.2 and 32.8% winter wheat yield reduction compared to the fallow–winter wheat rotation (2766 kg ha −1 ). Lower winter wheat yield in the alternative systems were offset by 907 kg ha −1 camelina and 1779 kg ha −1 barley yields. Economic analyses revealed that at existing market prices and production costs, the traditional fallow–winter wheat rotation provides greater net returns to growers due to substantially lower variable costs of the system. Scenario analyses that use more optimized, lower cost camelina production practices show that the net profits of camelina–wheat system could be closer to those in the fallow–wheat system. However, higher grain price and/or greater grain yield of camelina are essential to attract producers to include camelina in their cropping systems. Although the fallow–wheat system resulted in higher short-run net returns, the total biomass production and crop residue return to soil is much greater in camelina–wheat than fallow–wheat rotation, which is likely to improve soil quality and productivity in the long run. [ABSTRACT FROM AUTHOR]

Organic matter (OM) oxidized by slightly alkaline KMnO 4 , termed permanganate-oxidizable carbon (POXC), has recently emerged as a standardized indicator of active, labile carbon within soil quality frameworks. Yet, qualitative information on POXC, particularly in semiarid drylands, is very scarce. The aim of this study was to characterize POXC within three long-term field experiments in Montana, USA: (i) across a wide range of edaphic (e.g., % clay) and management conditions (e.g., cropping intensity) ( n  = 148); and (ii) to identify the molecular composition of soil OM before and after KMnO 4 treatment using electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI FT-ICR MS). The content of POXC was significantly greater under perennial (382–685 mg/kg) or annual cropping (404–607 mg/kg) than fallow-wheat (359–543 mg/kg) systems. Soil OM changes, however, were equally or better expressed when considering soil organic carbon (SOC) concentration. The occurrence of POXC paralleled SOC ( R  = 0.87; P  < 0.001) and total nitrogen (TN) ( R  = 0.82; P  < 0.001) concentrations, regardless of soil textural differences. The ESI FT-ICR MS analyses of aqueous soil extracts indicated that the KMnO 4 reaction oxidized dissolved OM of diverse molecular character. OM molecular composition after KMnO 4 treatment was enriched by strongly reduced chemical constituents (O/C < 0.4) at greater condensed aromaticity (AI > 0.67) and hydrogen saturation (aliphatic composition; H/C > 1.5) across all heterogeneous groups (C c H h N n O o S s ). Although POXC is a rapid assay widely used for characterizing soil OM dynamics, it may not provide a clear advantage over SOC concentration in semiarid drylands. The view of POXC as a merely labile, simple biodegradable OM fraction needs to be reconsidered. [ABSTRACT FROM AUTHOR]

Dissolved organic matter (DOM) plays a critical role in the cycling of nutrients and long-term agricultural sustainability. The composition of DOM in soil is likely altered due to management, yet there is limited knowledge on the effect of long-term cropping on DOM chemical character. Here, we characterized water extractable DOM composition along a gradient of soil organic carbon (SOC) affected by differing cropping and tillage intensity in a semiarid climate of the northern Great Plains, USA. Soil samples (0–10, 10–20, 20–30 cm) were collected from conventional till-fallow winter wheat ( Triticum aestivum L.; F till -W), no-till spring pea/oilseed-wheat ( Pisum sativum L.; P g /O-W), and no-till continuous wheat (W-W) fields, and analyzed using UV/Vis absorbance and excitation-emission matrix fluorescence spectroscopy. The concentration of DOM decreased with depth and was significantly greater ( P < 0.05) under W-W or P g /O-W than F till -W. The absorbance at 254 nm (Abs 254 ), a proxy for DOM aromatic nature, indicated that aromaticity decreased with depth and lower biomass-C inputs (i.e. W-W ≥ P g /O-W ≥ F till -W). Multidimensional parallel factor (PARAFAC) analysis revealed humic-like (C1, C2), monolignol-like (C3), and protein/tannin-like (C4) components with varying fluorescence intensities as a function of cropping system and soil depth. DOM humification, indicated by the humification index (HIX), increased significantly with depth ( P < 0.05) and was higher for F till -W (2.95) than W-W (2.61) or P g /O-W (2.28). Overall, DOM became depleted of plant-derived constituents and was enriched by more decomposed, condensed substances in F till -W, as compared to W-W or P g /O-W soils. DOM composition is strongly affected by cropping intensity and such changes are important drivers controlling SOC accretion in arable soils. [ABSTRACT FROM AUTHOR]

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. • Geographic location, farm management, and edaphic factors affect the free-living microbiome. • Irrigation disrupts general (16S) and diazotroph (nifH) bacteria communities differently. • Co-occurrence shifts in diazotrophic communities are due to irrigation. • Nitrogen-fixing keystone species are affected by irrigation in bulk soil [ABSTRACT FROM AUTHOR]