Winter wheat (Triticum aestivum L.) is usually grown in the Pacific Northwest (PNW) intermediate rainfall zone following tilled or chemical summer fallow. Studies were conducted near Davenport, WA and Helix, OR over two fallow–winter wheat cycles to evaluate the efficacy of reduced or no‐tillage fallow compared to conventional fallow and compare the efficacy of herbicides applied using a light‐activated sensor‐controlled (LASC) applicator to broadcast applications. Six treatments included conventional primary tillage followed by rodweeding; sweep‐tillage followed by rodweeding, broadcast, or LASC herbicide application; and no‐tillage followed by broadcast or LASC herbicide application. Broadcast and LASC herbicide applications controlled weeds similarly in no‐tillage treatments. However, LASC applications used from 45 to 70% less herbicide than broadcast applications to attain similar weed control. No‐tillage or sweep‐tillage systems with herbicide application had from 15 to 30% greater surface residue cover than the conventional tillage system. Available soil moisture in both the root‐zone and seed‐zone soil profiles at time of planting was similar among tillage systems. There were no differences in wheat quality parameters across treatments. The conventional tillage system had similar wheat grain yield as sweep‐tillage systems followed by rodweed or broadcast herbicide application, but yields were up to 21% greater than sweep‐tillage with LASC applied herbicides and no‐tillage systems. Reduced tillage systems using sweep‐tillage and broadcast herbicide application could potentially replace more tillage intensive fallow systems in the PNW.
The effects of seeding chickpea (Cicer arietinum L.) cultivars Dwelley and Sinaloa at different dates, row spacing, and rates were evaluated at the Columbia Basin Agricultural Research Center (CBARC) near Pendleton, OR. Highest seed yields and largest seeds were produced when both cultivars were seeded in early April. Delaying seeding until late April resulted in yield reductions of up to 6 lb/acre/day. Sinaloa produced significantly higher yields and larger seed than Dwelley at all the seeding dates. The optimum seeding rate for Sinaloa and Dwelley was 4.7 plants/ft2 and 3.4 plants/ft2, respectively. Dwelley produced higher yields in wider (12‐inch) than in narrower (6‐inch) rows and Sinaloa produced higher yields in narrower than wider rows. At the lowest plant population (2.1 plants/ft2), row spacing did not affect yields at all seeding dates. When seeded in early April, high chickpea yields were obtained when seeded in narrow rows at 3.4 plants/ft2 or in wider rows at 4.7 plants/ft2. Higher seeding rates increased yields in late seeded chickpeas when moisture was not limiting.
Millions of acres of cropland with as low as 6 inches annual precipitation are used for production of winter wheat (Triticum aestivum L.) in the Pacific Northwest of the USA. Despite soil conservation advances, soil erosion continues to be a problem. This on‐farm study analyzed seed‐zone soil water under farmer‐implemented fallow tillage practices to find out if very low‐disturbance systems are possible. A low‐disturbance, wide‐blade undercutter sweep treatment was similar or superior to the farmer's more intensive conventional tillage system. A subsequent test at four paired no‐till‐conventionally‐tilled summer‐fallow sites demonstrated that a single pass of an undercutter sweep in the no‐till field could preserve seed‐zone moisture comparable to the more intensive multiple‐pass conventional tillage. Despite conventional wisdom, summer‐fallow soil mulches do not need to be finely pulverized or repeatedly tilled to be effective.
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