Emergence of irrigated cotton in flatland planting in relation to furrow opener type and crust-breaking treatments for Cambisols in central Iran

Emergence of cotton (Gossypium hirsutum L.) under flatland mechanized planting system with crust-forming soil and saline soil and irrigation water can be suboptimal in central Iran. A field experiment was conducted to determine furrow opener type and crust-breaking method effects on cotton emergence on a silty clay soil (Calcic Cambisols). The effects of five planters (equipped with runner, single- and doubledisk type openers) and five crust-breaking methods (using rolling cultivator, rollingtype crust breaker, spike-tooth, chain-type harrows and no crust-breaking) on the seedling emergence were studied. The results showed that planter type significantly affected cotton seedling emergence. In non-crust-breaking method, the best emergence was produced with the double-disk opener planter that created crack lines along the seed rows. This phenomenon was not observed with the runner-type opener planter. However, some crack lines were observed on the outside edges of its smooth-crown zero-pressure press wheels tires, which resulted in large clod formation after crust-breaking and had therefore negative effect on seedling emergence. Crust-breaking had negative effect on final emergence for double-disk planter due to filling the crack lines with loosened soil. Crust-breaking improved emergence percentages for runner opener planters, when the depth of penetration of the crust breaker teeth was shallow. The conclusion is that irrigated cotton emergence on crust-forming soils in a flatland planting system might significantly be improved by selecting a double-disk planter with zero-pressure press wheel tires without any crust-breaking operation under the soil and climate of central Iran.