Effect of Herbicides and Tillage Techniques on the Grain Productivity of Pea in the Steppe Zone of the Kabardino-Balkarian Republic

The effect of herbicide application and soil tillage techniques on weed growth and grain yield of the pea variety Kadet has been evaluated. The study was performed in 2016–2018 under conditions of the steppe zone of the Kabardino-Balkarian Republic. The soil of the experimental area represented pre-Caucasian carbonate chernozem with a heavy loamy granulometric composition. The experimental design consisted of the following variants. The tillage technique (factor A) included a moldboard plowing by PLN-4-35 with the plowing depth of 25–28 cm, subsurface flat-cutting tillage by a flat-cutter KPG-2.2 to the depth of 25–28 cm, and subsurface chisel tillage by AKP-2.5 with chisel paws to a depth of 16–18 cm. The treatment with herbicides (factor B) included the herbicide-free variant; preemergence treatment with the Tristar, SK herbicide (2.5 L/ha) under “blind” harrowing; treatment with the Garnizon, WS herbicide (2.0 L/ha) at the three- to five-leaf stage); and Tristar, SK (2.0 L/ha) + Garnizon, WS (2.0 L/ha) applied at the specified periods. The maximum weed kill rate observed in the experiment (81.2%) was recorded 28–30 days after the crop treatment for the variant with Tristar, SK combined with the moldboard tillage. A combined application of the Garnizon, WS and Tristar, SK herbicides was effective regardless of the tillage technique used (weed kill rate up to 75–79%). A decrease in a weed infestation observed to the end of the vegetation period contributed to an increase in the pea grain yield from 2.2–2.6 to 2.4–2.9 t/ha. The largest yield increase in the experiment (0.5–0.6 t/ha) was observed for the combined use of the Tristar, SK and Garnizon, WS herbicides.