|Fjell, D - KSU, MANHATTAN, KS|
|Gerik, T - TEXAS A&M, TEMPLE, TX|
Submitted to: Proceedings Great Plains Soil Fertility Conference
Publication Type: Proceedings
Publication Acceptance Date: January 15, 2000
Publication Date: March 5, 2000
Citation: Halvorson, A.D., Fjell, D.L., Gerik, T.J. 2000. Can narrow row spacing improve sunflower and corn yields in the great plains?. Proceedings Great Plains Soil Fertility Conference. Kansas tate University, Manhattan and Potash and Phosphate Institute, Brookings, SD. 8_158-164. Interpretive Summary: Studies were conducted from North Dakota to Texas to determine the effects of narrow row spacing (20 inch or less) on corn and sunflower yields when compared to traditional row spacings. Sunflower yields in North Dakota were increased 13% with row spacings of 7.5 and 15 inches compared with 30 inch row spacing. Dryland, no-till corn yields were increased 30 and 24% with row spacings of 7.5 and 15 inches compared to 30 inch rows in North Dakota. Dryland and irrigated corn yields were increased by using 15 inch row spacing compared with traditional 30 inch row spacing. Dryland corn yields in Texas were increased by using 20 inch row spacing compared with traditional 40 inch row spacing These results suggest that corn and sunflower yields in the Great Plains can be enhanced with narrow row spacing. Research is needed to determine the effects of narrow row spacing on crop nutrient requirements for optimum yield and nutrient use efficiency.
Technical Abstract: No-till (NT) increases the potential to intensify cropping frequency under dryland conditions in the Great Plains. More frequent cropping requires N input to maintain economical yields. We evaluated the effects of long-term N fertilization on crop residue production and its subsequent effects on soil organic C (SOC) in four dryland cropping systems and one irrigated cropping system. Nitrogen rates had been applied to the same plots from 9 up to 30 years. Cropping systems included two annual cropping systems, one wheat-corn (sorghum)-fallow, one wheat-fallow, and one irrigated sugarbeet- rotation. Crop residue production varied with cropping and tillage system, but increased with increasing N rate in all systems. Increased amounts of crop residue returned to the soil with increasing N rate resulted in increased levels of SOC in the Colorado studies. In North Dakota, SOC was not influenced by N rate or tillage system in a spring wheat-fallow rotation. However, NT resulted in increased SOC levels over that of minimum-till (MT) and conventional-till (CT) systems in spring wheat-winter wheat-sunflower rotation. At the intensively tilled irrigated site in Montana, SOC levels declined from 1953 to 1983, with SOC levels being lowest with the lower N rates. At the highest N rate, 400 lb N/a, SOC was maintained near the initial 1953 SOC level. SOC levels can be enhanced by increasing crop residue production through adequate N fertility.