Field pea (Pisum sativum L.) has been introduced recently as a rotational crop in the semi‐arid region of the northern Great Plains. Very little is known about the response of field pea varieties to management practices such as planting date and seeding rate in this environment. This study was conducted at two locations in 2004 to 2006 to determine the effect of seeding rate on field pea establishment, yield, and yield components. In addition, seeding rates required for economic optimum yield were determined. The study had four varieties with contrasting morphology and six seeding rates ranging from 25 to 90 viable seeds/m2. Increasing seeding rate increased seedling density and seed yield. Harvest index and plant height were relatively constant across seeding rates. Pea plants compensated for low plant populations by producing more pods per plant and more seeds per pod although this compensation mechanism was not enough to maintain high yield at low populations in all environments. Seeding rates that gave best partial net economic returns varied from year to year, but with a trend for lower returns at seeding rates greater than 77 seeds/m2. A target seeding rate of 64 to 77 seeds/m2 is suggested for the region.

Crested wheatgrass [Agropyron cristatum (L.) Gaertn., A. desertorum (Fisch. ex Link) Schult., and related taxa] oft en exists in near monoculture stands in the northern Great Plains. Introducing locally adapted yellow-fl owered alfalfa [Medicago sativa L. subsp. falcata (L.) Arcang.] would complement crested wheatgrass. Our objective was to evaluate eff ects of seedingpropyl]-5-[2-(ethylthio)propyl]-3-hydroxy-2-cyclohexen-1-one} sod suppression, and seeding rate on initial establishment and stand persistence of Falcata, a predominantly yellow-fl owered alfalfa, no-till interseeded into crested wheatgrass. Research was initiated in August 2008 at Newcastle, WY; Hettinger, ND; Fruitdale, SD; and Buff alo, SD. Eff ects of treatment factors on plant frequency during initial establishment were infl uenced by site environments. Late summer and spring were suitable seeding dates. Clethodim sod suppression increased seedling frequency in most cases. Seedling frequency increased as seeding rate increased from 0.56 to 7.84 kg pure live seed (PLS) ha -1 . Specifi c seeding dates, clethodim sod suppression, and high seeding rates did not greatly improve initial establishment when site environments were poor. Residual eff ects of seeding date and sod suppression post establishment were not signifi cant at most locations, but seeding rate eff ects were evident. Initial establishment and persistence of Falcata alfalfa was successful at Newcastle, indicating that interseeding in late summer or spring using low seeding rates (≤3.36 kg PLS ha -1 ) without clethodim can be eff ective. Assessing grass canopy cover, soil texture, and management (e.g., haying) is necessary to determine the suitability of crested wheatgrass sites for interseeding.

Producers in the semiarid Great Plains are exploring alternative crop rotations, with the goal of replacing winter wheat–fallow. In 1993, a study was established to compare performance of eight rotations comprised of various combinations with winter wheat (W), spring wheat (SW), dry pea (Pea), safflower (Saf), corn (C), sunflower (Sun), proso millet (M), or fallow (F). After 8 years, we characterized weed communities by recording seedling emergence in each rotation. Seventeen species were observed, with downy brome, kochia, horseweed, and stinkgrass comprising 87% of the community. Rotations with the least number of weed seedlings were W–F and SW–W–C–Sun; in comparison, weed density was six-fold higher in W–M. Density of downy brome and kochia was highest in W–M compared with other rotations, whereas stinkgrass and green foxtail were prominent in proso millet of the W–M and W–C–M rotations. Horseweed established readily in safflower and dry pea. In the semiarid Great Plains, designing rotations in a cycle of four that includes cool- and warm-season crops can be a key component of integrated weed management.

Durum wheat (Triticum durum Desf.) is a market class of wheat subject to price discounts in the marketplace if quality standards are not met. This study was conducted in order to determine how certain agronomic practices might impact durum wheat quality. The effects of planting date (PD), cultivar, and seeding rate on agronomic and semolina quality traits were investigated in field trials conducted near Hettinger and Minot, ND in 2014 and 2015. The interaction of PD and cultivar was significant for many of the traits evaluated. There was a significant PD X cultivar interaction or PD and cultivar effect for yield in all environments. Planting date X cultivar interacted for test weight at all environments. In general, a delay in PD resulted in a significant decrease in yield and test weight for all cultivars. However, Carpio yielded more than other cultivars in high yielding environments while the yield and test weight of Joppa was more adversely affected by delays in PD. Seeding rate did not have a consistent effect on any agronomic or quality trait. Protein content, kernel yellow pigment content, falling number (FN), and vitreous kernels were more dependent on cultivar, regardless of PD and environment. Semolina extraction, gluten index (GI), and wet gluten (WG) values tended to decrease with a delay in PD. These data continue to support cultivar selection as a critical component for obtaining high-yielding, high-quality durum wheat. However, PD and environment can impact certain agronomic and end-use traits, regardless of cultivar grown.

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