ARS | Publication request: NITROGEN MICRONUTRIENT AND ROW SPACING RESPONSE OF SUNFLOWERS

Submitted to: High Plains Research Summary
Publication Type: Proceedings
Publication Acceptance Date: December 27, 2000
Publication Date: January 1, 2000

Interpretive Summary: Since 1990, the Central Great plains region has had phenomenal increase in sunflower planted acres of over 800,000. However, knowledge of sunflower response to fertilizer N and micronutrients in the region is limited. Similarly the basic agronomics of sunflower culture is new to the region and the development of cultural practices (weed control, seeding rates , row spacing etc.) needed to fully exploit the current genetic potential is needed. The objectives of these studies are: (i) to measure N and micronutrient response under no-till managed summer fallow, (ii) to compare narrow row (20") production with conventional (30") row spacing. No-till dryland sunflowers are planted in field plot experiments replicated four times. Main plots consist of rotation crop/phase (a wheat-proso millet(or corn)-sunflowers-fallow rotation). Sub-plots are fertilized at N rates of 0, 30, 60, or 90 lbN/acre and planted in either 20 or 30 inch rows. Two rows are sprayed with zinc, copper, manganese and boron. Surface and deep placed 15N labeled N is being used to evaluate fertilizer N recovery with soil depth and fertilizer recovery with N placement. Most years sunflowers do not give an economic yield response to any fertilizer nutrients. In wet years maximum yield was measured at 60 and 90 lbs N/acre and greater yield s were measured when sunflower was planted in 20 inch rows as compared to 30 inch rows.

Technical Abstract: Since 1990, the region has had an increase in sunflower planted acres of over 800,000. However, knowledge of sunflower response and fertilizer recovery of N and micronutrients in the region is limited. The objectives of these studies are: (i) to measure N and micronutrient response under no-till managed summer fallow, (ii) to compare narrow row (20") production with conventional (30") row spacing. No-till dryland sunflowers are planted in a randomized split-split plot experiment and replicated four times. Main plots consist of rotation crop/phase (a wheat-proso millet(or corn)-sunflowers-fallow rotation). Sub-plots are fertilized at N rates of 0, 30, 60, or 90 lbN/acre. Each N rate plot is divided in half and each half plot is planted in either 20 or 30 inch rows. Two rows are sprayed with zinc, copper, manganese and boron. Surface and deep placed 15N labeled N is being used to evaluate fertilizer N recovery with soil depth and fertilizer recovery with N placement. Most years sunflowers do not giv an economic yield response to any fertilizer nutrients. In wet years maximum yield was measured at 90 lbs N/acre and greater yield s were measured when sunflower was planted in 20 inch rows as compared to 30 inch rows.