Two-dimensional (2D) materials are among the most promising candidates fornext-generation electronics due to their atomic thinness, allowing for flexible transparent electronics and ultimate length scaling 1 . Thus far, atomically-thin pn junctions 2-8 , metal-semiconductor contacts 9-11 , and metal-insulator barriers [12][13][14] have been demonstrated. While 2D materials achieve the thinnest possible devices, precise nanoscale control over the lateral dimensions are also necessary.Here, we report the direct synthesis of sub-nanometer-wide 1D MoS2 channels 2 embedded within WSe2 monolayers, using a dislocation-catalyzed approach. The 1D channels have edges free of misfit dislocations and dangling bonds, forming a coherent interface with the embedding 2D matrix. Periodic dislocation arrays produce 2D superlattices of coherent MoS2 1D channels in WSe2. Using molecular dynamics simulations, we have identified other combinations of 2D materials where 1D channels can also be formed. The electronic band structure of these 1D channels offer the promise of carrier confinement in a direct-gap material and charge separation needed to access the ultimate length scales necessary for future electronic applications.Reducing the lateral scale of atomically thin 2D devices is crucial not only to realize competitive electronic device applications, but also for reaching the length scales needed for quantum confinement. Thus far, the many 2D heterostructure devices rely on the lithographic patterning of one 2D layer followed by the growth of another in the patterned areas [9][10][11][12] . While this technique provides spatial control down to below a hundred nanometers or so, the nature of the lithographic patterning creates atomic defects and contamination. Consequently, the atomic junctions in these heterostructures contain electronic defect states, impacting device performance.Recently, the growth of micron sized in-plane epitaxial interfaces between 2D materials has been reported using chemical vapor deposition (CVD) methods [3][4][5][6][7][8]13,14 .Theory predicts a tunable carrier confinement 15 and formation of 1D electron gas 16 at the abrupt and coherent interfaces in heterostructures of 2D materials that are just a few atoms wide. The atomic-scale heterostructures are usually chosen for computational convenience, but there would be benefits to realizing such narrow physical structures. For example, in contrast to broad in-plane heterostructures which 3 ultimately generate misfit dislocations to release the lattice strain, thin channels can sustain large strains without relaxation and hence access a wider range of electronic band structures. Just as in bulk materials, dislocation formation can be suppressed below a critical film width 17 , which scales inversely with the desired strain -several nanometers are typical for mismatch in the family of 2D transition metal dichalcogenides (TMDs). The thin channels always have one dimension below their critical thickness, ensuring stability against dislocation formation at the ...

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Information is lacking on the relative performance of small‐grain forage types grown for hay or silage on the High Plains of New Mexico and West Texas. Tests were conducted from 2004 to 2008 at Clovis, NM, to determine long‐term potential of common varieties and blends of species [wheat (Triticum aestivum L.), triticale (xTriticosecale), and oats (Avena sativa L.)] in an irrigated production system. Eleven entries were tested in at least 3 years, including exceptionally wet (2005) and dry (2006) years. In any given year, all crops yielded greater than 2.5 tons of DM, and entry mean annual yields ranged from 4.0 to 5.3 ton DM/acre over the study period. Triticale or blends containing triticale yielded more wet forage than wheat alone. In general, nutritive value of wheat was greater than that of triticale and blends. One triticale entry exhibited similar DM yields and forage quality as those of the wheats. Under irrigation, small grains have the potential to produce acceptable yields of nutritious forage in between summer crops for feeding operations in the region. While wheat may yield less tonnage, it gives greater market flexibility and may better fit into double cropping systems because of its earlier maturity than triticale.

Intercropping legumes with nonlegume crops has shown benefits in improving dry matter (DM) yield, but additional information is needed when crop mixtures are ensiled. This study assessed the fermentation characteristics of forage corn silage {Zea mays L.) (CS) and forage sorghum silage [Sorghum bicolor (L.) Moench] (FS) when mixed with different proportions of lablab bean [Lablab purpureus (L.) Sweet] (LB). Corn, FS, and LB were grown in separate fields at two locations in 2009. At each location, crops were cut and chopped separately and taken to the laboratory for ensiling. Six mixtures were handmade on a percentage fresh weight basis for each CS-LB and FS-LB combination, including (i) 100:0, (ii) 90:10, (iii) 75:25, (iv) 50:50, (v) 25:75, and (vi) 0:100.For each mixture, a 1-L glass jar (mini-silo) was filled with 500 g of fresh material, with four jars per treatment. Forage in mini-silos was fermented for 60 d at room temperature (25°C). Analysis was conducted for nutritive value and fermentation characteristics. The greatest impact of mixing LB with CS or FS was on crude protein (CP) and acid detergent fiber (ADF) concentrations, with no significant impact on neutral detergent fiber (NDF). Averaging across CS and FS, CP concentration increased from 87 to 173 g kg-'' and ADF concentration from 253 to 306 g kg-^ as LB increased from 0 to 75% in the mixture. Increasing LB in the mixture also increased other constituents, such as pH and lactic and acetic acid concentrations. Adding LB to CS or FS for silage can have a positive effect on the final nutritive value, but additional research is needed to assess the impact in cattle.

Forage sorghum [Sorghum bicolor (L.) Moench] and sorghum & sudangrass (S. bicolor var Sudanese) hybrids may produce as much dry matter yield as corn (Zea mays L.) for silage but with less water. Planting sorghum forage with annual legumes could increase digestibility and crude protein (CP) concentration, making the mixture more suitable for dairy cow rations. The objective of this study was to assess dry matter (DM) yield and nutritive value of brown midrib (BMR) sorghum forage grown as a monoculture or in combination with selected annual legumes. BMR100 (a forage sorghum) and PS210BMR (a photoperiod sensitive sorghum & sudangrass) were planted with four annual legumes: cowpea [Vigna unguiculata (L.) Walp.], lablab (Lablab purpureus L.), soybean (Glycine max L.), and tepary bean (Phaseolus acutifolius A. Gray). Lablab was most complementary with sorghum for forage. The lablab‐sorghum mixtures contained more CP with no consistent effect on neutral detergent fiber (NDF) and acid detergent fiber (ADF) compared to monoculture sorghums. This finding opens another possibility to produce good quality forage that could be used as an alternative forage crop to corn in the Southern High Plains.

Bermudagrass [Cynodon dactylon (L.) Pers.] forages are potential alternatives to traditional row cropping in the Southern High Plains. Early persistence of certain bermudagrass selections and economic potential and nutritive value of known, improved cultivars in semiarid West Texas are uncertain. A 2‐yr study was conducted to evaluate hay productivity and nutritive value of 10 cultivars and two selections of bermudagrass grown with subsurface drip irrigation. Grasses were irrigated with 312 mm of water from 1 May through 31 August in 2002 and 2003. Precipitation amounts during the growing season (May–September) were 195 and 184 mm for 2002 and 2003, respectively. ‘Tifton 85’ yielded the highest total annual biomass (20.4 Mg ha−1) and resulted in high irrigation water use efficiency (IWUE; 65.2 kg ha−1 mm−1). ‘World Feeder’ and ‘Macho’ performed poorly with respect to yield when compared with the other 10 grasses. Although Tifton 85 exhibited high acid detergent fiber (ADF; 349 g kg−1) and low total nonstructural carbohydrates (TNC; 93 g kg−1), in vitro dry matter disappearance (IVDMD) was greatest (622 g kg−1) when contrasted with the mean of all other cultivars. Yields were similar for sprigged and seeded types. Results indicate that several bermudagrass cultivars maintained high yields and adequate nutrition 2 yr after establishment and, based on IWUE, may be an economically sound alternative to the existing cotton (Gossypium hirsutum L.) monoculture in the region.

Core Ideas The soil organic C dynamics and net ecosystem C balance of five dryland cropping systems were compared. Conservation systems stored up to 15% more soil organic C than conventional system. Net ecosystem C balance was positive with cover cropping. Cover crops and conservation tillage are crucial for soil C storage in drylands. Biomass C inputs often limit agroecosystem C dynamics, nutrient cycling, and soil organic carbon (SOC) storage in semiarid drylands. This study evaluated SOC and net ecosystem carbon balance (NECB) of five cropping systems in the drylands of the Southern Great Plains. Cropping systems evaluated included corn (Zea mays)–sorghum [Sorghum bicolor (L.) Moench] rotation with conventional tillage without cover cropping (CTNC), strip tillage with and without cover cropping (STCC and STNC, respectively), and no tillage with and without cover cropping (NTCC and NTNC, respectively). After 4 yr of experimental tillage, we measured CO2 emissions, soil and soil surface air temperatures, soil moisture content, potentially mineralizable carbon (PMC), total SOC, total nitrogen (TN), and net primary productivity (NPP). Conservation systems (any treatments including no‐till, strip till, or cover crops) had 5 to 6°C lower soil temperature and 2.8 to 4.9°C lower soil surface air temperature and stored 2.3 to 3.9% more soil moisture content than CTNC. Conservation systems also stored 15.2% more SOC than CTNC. Cropping systems that integrated cover crops in the rotation (STCC and NTCC) had greater NPP and positive NECB. Regardless of tillage management, cover cropping had a greater NECB, including SOC (NECBSOC) than CTNC. Reducing tillage and diversifying cropping systems through cover cropping can benefit semiarid dryland agroecosystems by increasing SOC storage and maintaining positive NECB.