Irrigated Sunflowers

Sound water management is essential to the success of sunflower crops.

June 2017

Hans Kandel, NDSU Extension Agronomist

Sunflower is commonly grown as a dryland crop. Research and farmer testimony has demonstrated that sunflower responds to irrigation with yield increases of 100 to 200% over dryland yields common on droughty soils and in extremely dry years. Sunflower adapts to a wide range of soils and climatic conditions. Low sunflower yields may be caused by any of the following: incorrect plant population, poor soil fertility, lack of weed control, diseases, insect damage, bird depredation, lodging, late planting, and harvesting losses. Management of all factors listed plus sound water management are essential.

Average yields of 26 sunflower hybrids and varieties at the NDSU Carrington Irrigation Research Station in the late 70's were 3,222 lb/A for irrigated sunflower compared wtih1,126 lb/A for dryland sunflower (Table 1). These average yields represent a 196% yield increase of irrigated over dryland sunflower. During another year white mold caused yields of irrigated sunflower to be similar to dryland yields (Table 2). Rainfall also was above normal for the second growing season. Plant populations were 22,000 plants per acre, 28 inches of water was applied by furrow irrigation, and fertilizer applied included 94 lb/A 46-0-0, and 300 lb/A 23-23-14.

Under the irrigation management, some lodging was reported, especially in the taller varieties. A large portion of the lodging was attributed to root lodging with the plants leaning primarily because of heavy top weight and lack of support by wet soil in the root zone. Some neck breakage occurred in the irrigated trials, however, only a few heads were reported to be completely lost. Plant populations of 24,000 to 28,000 plants/A are recommended for irrigated sunflower production planted in 30 inch row spacings.

Water utilization by sunflower depends on a number of factors including variety, date of planting, timing of irrigation, soil types, fertility, and plant populations. Optimum utilization of water occurs if N, P and K levels are sufficient for high yields. All nutrient requirements of sunflower must be met for most effective use of water. Robinson, at the University of Minnesota, reported that irrigation, fertilizer, and irrigation + fertilizer increased sunflower yields 35, 72 and 474%, respectively.

Water deficiency between flowering and maturity adversely influences yield more than at other times. Irrigation management becomes much more critical from early flowering until maturity. Irrigation should maintain soil moisture at 80% of field capacity at flowering stages and at 70% of field capacity at other times. Seed yields increased 30% and oil yields 48% from irrigation 22 days after mid-flower as reported by sunflower workers in Australia.

The exact timing and number of irrigations depend on rainfall distribution and stored soil moisture. Typical of all high value irrigated crops, monitoring of the crop and top level management practices are vital in order to obtain high economic returns.

In 3 years of field tests in Texas, it was reported that sunflower would yield fairly well with adequate moisture at planting time and then one additional watering at flowering time. Top yields of dryland vs. irrigation reported were 1,580 lbs. to 3,330 lb/A in year 1, from 820 to 2,330 lb/A in year 2 and 1,740 to 2,970 lb/A in year 3. Sunflower should have either rainfall or some irrigation every 14 days to reach maximum yield. Adequate moisture at planting time and perhaps one good watering at bloom or just prior to bloom may pay off more than where sunflower is watered several times. High costs of energy involved in irrigation may prove this type of scheduling to be economically sound. More research must be conducted to thoroughly address this problem of water use and scheduling.