Strip tillage width effects on sunflower seed emergence and yield

Strip tillage is a conservation practice in which narrow strips, generally totaling less than 50% of the field area, are tilled. We hypothesized that strip tillage would be beneficial for long-term soil quality improvement, erosion control, and environmental protection because it also protects crop residues so they can cover and continuously protect the soil surface. A two-year field experiment with three replicates was conducted to quantify effects of three strip widths on selected soil physical properties, seed emergence and yield of sunflower (Helianthus annuus). A powered row crop rotary hoe which is a group of narrow rotary tillers spaced evenly along the width of the toolbar and powered by the tractor power take-off was used to till soil in strips. The rotary hoe was equipped with C-type blades and was used to till strip widths of 37.5, 30 and 22.5 cm by changing the blade position and number of flanges on each row of the rotary hoe. A constant rotor rotational speed (370 rpm), forward tractor speed (5.4 km h-1) and tillage depth (10 cm) were used to create the three strip widths that corresponded to tilled zones encompassing 50, 40, and 30% of the field area, respectively. A pneumatic seeder with 75 cm row intervals was used for planting. The results show that as strip width increased, soil temperature increased but soil moisture content decreased due to evaporation loss from the tilled surface of the strips. Sunflower seed emergence ranged from 67 to 93%, with the lowest levels occurring with 22.5 cm strips. Plant length and stalk diameter also increased as strip width increased. Seed yields for the two years also increased with strip width, averaging 4.4, 4.1, and 3.9 Mg ha-1 for the 37.5, 30 and 22.5 cm strip widths, respectively. Based on these results, although seed yield was least for the 22.5 cm strip width, tractor fuel efficiency was greatest for that width and the soil tended to retain more moisture for that width, compared to the 30 and 37.5 cm widths, so the 22.5 cm strip width is recommended to the eastern Turkey.