http://hdl.handle.net/2097/1069 Search the Channel search http://krex.ksu.edu/dspace/simple-search http://hdl.handle.net/2097/1280 Title: Soybean yield and yield component response to plant density in narrow row systems<br/><br/>Authors: Epler, Michael; Staggenborg, Scott<br/><br/>Abstract: Soybean (Glycine max) yield is responsive to changes in plant population and row spacing under dryland conditions. Soybean seeding rate recommendations in many states were developed prior to the release of herbicide tolerant varieties when soybean seed costs were lower. As a result, many recommendations are high, and soybean performance at low plant densities in narrow rows needs to be reevaluated. This study was conducted to evaluate soybean yield response to plant density in narrow row, drilled systems (7.5 and 15 in) and evaluate the effects of plant population on yield components. The study was conducted in six environments with optimum plant populations ranging from 80 000 to 140 000 plants acre [superscript]-1. The two yield components responsible for the yield optimization were pods plant [superscript]-1 and pods acre [superscript]-1. As plant population increased, pods plant [superscript]-1 decreased steadily; however, yield was not reduced either year of the study by the loss of pods plant [superscript]-1 because pods acre [superscript]-1 increased as plant population increased. The optimum seeding rates for each year of the study were below the 150 000 to 160 000 plants acre [superscript]-1 seeding rate normally recommended in the region. The decreased optimum plant populations in both years did not adversely affect yield and might be useful in reducing input costs in dryland soybean production. Tue, 03 Mar 2009 21:14:30 GMT http://hdl.handle.net/2097/1108 Title: Grain sorghum and corn comparisons: Yield, economic and environmental responses<br/><br/>Authors: Staggenborg, S.A.; Dhuyvetter, K.C.; Gordon, W.B.<br/><br/>Abstract: Grain sorghum (Sorghum bicolor (L.) Moench) is often grown where water stress is expected. But, improved drought tolerance in corn (Zea mays (L.)) hybrids has resulted in increased dryland corn production in preference to grain sorghum. However, grain sorghum may still have a yield advantage over corn in drought prone environments. This study was conducted to determine if grain sorghum has either a yield or economic advantage over corn when drought or temperature stress occurs. . Yield and weather data from crop performance testing programs in Kansas and Nebraska (1992 - 2005) were analyzed. Grain sorghum produced higher yields than corn in environments where corn yields were less than 6.4 Mg ha-1. When net returns ($ ha[superscript]-1) were considered for grain sorghum prices that were set at 70, 87, 100, and 117% of corn prices, grain sorghum net returns were higher than corn net returns when corn yields were equal to or less than 4.4, 6.6, 8.8, and 13.6 Mg ha[superscript]-1, respectively. Both corn and grain sorghum yields were positively correlated to June through August precipitation and negatively correlated to June through August maximum temperatures. The yield difference (grain sorghum minus corn) increased as July and August maximum temperatures increased. Monthly minimum temperatures affected corn yield less than grain sorghum yield. Producers in this region likely can minimize production risks by considering this historical yield information. At locations in this region where corn yields are consistently less than 6.4 Mg ha[superscript]-1, producers should consider producing grain sorghum. Fri, 19 Dec 2008 21:58:52 GMT http://hdl.handle.net/2097/1086 Title: Effect of planter speed and seed firmers on corn stand establishment<br/><br/>Authors: Staggenborg, S.A.; Taylor, R.K.; Maddux, L.D.<br/><br/>Abstract: Proper planter adjustment and operation play an important role in uniform stand establishment for corn. A two−year study was conducted to assess the impact of planter speed and a seed−firming device on corn stand establishment and grain yield. A planter equipped with a vacuum metering system and commercial seed firming devices was used in this study. Corn was seeded in a randomized complete block experiment at three speeds at two locations in Kansas (USA). Plantstand was counted at regular intervals after the first plant emerged to determine emergence rate. Plant spacing within each treatment was measured after complete emergence. Mean plant spacing, standard deviation in spacing, and four spacingindices (miss, multiple, quality of feed, and precision) were calculated to evaluate the plant spacing data. The miss and multiple indices indicate the number of skips and doubles. Planter performance as measured by these indices and standard deviation in plant spacing decreased as planter speed increased. The seed firmer reduced plant spacing standard deviations at a rate equivalent to the standard deviation increase observed when planter speed increased approximately 1.6 km/h (1 mph). Corn yield was reduced as planter speed increased at one location, but not the others. This response was the result of lower plant densities at the higher planter speeds, suggesting that one of the goals of the planting process should be to establish adequate plant densities. The seed firmer had no impact on corn yield. Thu, 18 Dec 2008 22:14:07 GMT