Response of Sunflower to Nitrogen and Phosphorus in North Dakota

Abstract

Core Ideas Nitrogen availability and fertilization can increase sunflower see yield.Nitrogen fertilization may decrease oil concentration of oilseed sunflower.Nitrogen fertilization increases sunflower lodging risk in windy regions. The N and P recommendations for sunflowers growers in North Dakota have not been changed in 30 yr. Twenty‐two N and P rate experiments were conducted during 2014 and 2015. The objective was to determine the response of seed yield, oil concentration, and lodging to available N and P. In 2014 studies were a randomized complete block split plot with N rate as main plots and P rate as subplots. Nitrogen was applied at rates of 0, 45, 90, 134, 179, and 224 kg N ha−1. Phosphorus was applied to establish P rates of 0, 13, 26, and 39 kg P ha−1. In 2015, the field design included only 0 and 26 kg P ha−1. Experiments were taken to yield and lodging was recorded at harvest. Oil seed sunflower (17 experimental locations) was also analyzed for oil concentration. The N response of sunflower seed yield was quadratic. Increased N rate resulted in lower oil concentration in half of the oilseed experiments. Increased N rate was linearly related to increasing lodging at several sites. Phosphate fertilization had little effect on seed yield, oil concentration, and lodging, despite many of the sites having soil P levels considered ‘low’. Future N rate recommendations should be based on seed yield response with increasing N and oil concentration reduction with increasing N for oilseed sunflower. A limit to maximum N rate should also be considered because of the lodging risk in this wind‐plagued region.

A Case Study of Potential Reasons of Increased Soil Phosphorus Levels in the Northeast United States

“…The amount of work required increased by the need to develop recommendations for multiple regions that consider the effects of different soil types, climates, crop growth habits, and crop requirements. Several studies documented that soil type variation could have a significant impact on P response towards crop yield [29][30][31][32][33], as demonstrated in the introduction. A study at University of Kentucky on P showed the differences that occurred from testing soil P (Mehlich III solution) using different soils with the same rate of P application [33].…”

“…Several studies documented that soil type variation could have a significant impact on P response towards crop yield [29][30][31][32][33], as demonstrated in the introduction. A study at University of Kentucky on P showed the differences that occurred from testing soil P (Mehlich III solution) using different soils with the same rate of P application [33]. Therefore, it was necessary to study the soil types in Maine and Aroostook County, Maine.…”

Complete Issue

“…However, these treatments were not significantly different from the control. Schultz et al (2018) also found that sunflower yield increased with N rate until reaching the critical level and the required N rate to maximize the yield at the conventional tillage site of eastern North Dakota was 200 lb N/ac. For this study, total soil available N (initial soil N + fertilizer N) for the 100% of recommended fertilizer N treatment was close to 190 lb N/ac.…”

“…Current fertilizer N recommendation for eastern conventional till oilseed sunflower N recommendation ranges between 47 and 150 lb N/ac based on the cost of fertilizer N and sunflower price (Franzen, 2016). Recently, Schultz et al (2018) reported that 14 out of 21 sites responded to fertilizer N additions with the yield response curve in response to incremental fertilizer N application rates following a quadratic relationship in North Dakota and South Dakota.…”

Key traits and genes associate with salinity tolerance independent from vigor in cultivated sunflower (Helianthus annuusL.)

“…Taken together, these traits suggest nutrient uptake, and/or allometric scaling of root traits with vigor (Wang et al, 2019), as key components in vegetative growth. In a field setting, increased fertilization indeed produces increased growth in sunflower, though this did not ultimately translate into a yield increase; instead, it resulted in increased lodging and reduced yields (Schultz et al, 2018). This finding highlights the complexity of translating vegetative growth to yield.…”