Location: Crop Production Systems Research2013 Annual Report
1a. Objectives (from AD-416):
1: Develop sustainable management strategies for cotton, corn, soybeans and other crops grown in the mid-southern United States, and determine the impact of crop rotations, tillage, and herbicide regimes on crop physiology and weed control options. 2: Evaluate the impact of crop management on quality traits of various crops in the system, including cotton (gossypol, boll development, maturity, length, strength, and uniformity) and soybean (fatty acid profiles and protein quality).
1b. Approach (from AD-416):
Conventional corn hybrids and transgenic corn hybrids containing insect and herbicide resistance traits will be compared for variation in physiological components, mycotoxin contamination, insect damage, agronomic performance and economic return. Maturity group IV and V soybean varieties will be grown in both twin-row and single row planting patterns to compare their growth, photosynthesis, and agronomic performance. Glyphosate resistant corn hybrid grown in both twin-row and single row planting patterns will be evaluated for canopy light interception, photosynthesis, weed population densities, and agronomic performance. Conventional and glyphosate-resistant cotton-soybean rotation will be initiated under minimum tillage to assess impact on various soil properties, weed population densities, plant nutrition, cotton physiology, seed composition, crop agronomic performance, and economic return. Barnyardgrass and junglerice populations will be surveyed at various sites within the mid-southern region of the U.S. and characterized for morphological diversity and variation in growth parameters. Weed populations will be monitored throughout the growing season in glyphosate resistant soybeans grown in twin-row pattern to address issues with late season weed control. Different crop management systems for corn, cotton, and soybeans will be utilized on land infested with cogongrass to determine effectiveness and economic viability of various cogongrass control options. Obsolete and modern cotton varieties consisting of both conventional and transgenic types will be grown at two different plant population densities and assessed for variation in dry matter partitioning, canopy light interception, growth analysis, and agronomic performance. Diverse cotton varieties grown under either irrigated or dryland conditions and with 3 different levels of nitrogen fertilization will be assessed for dry matter partitioning, canopy light interception, chlorophyll fluorescence, and agronomic performance. Normal, okra, and super-okra leaf type isolines in the same genetic background will be grown in both twin-row and single row planting patterns and assessed for dry matter partitioning, canopy light interception, growth analysis, and agronomic performance.
3. Progress Report:
The results from the agronomic, physiological, and crop culture studies gave insight to physiological mechanisms leading to lint yield and fiber quality differences among diverse cotton varieties. A uniform population density of 1.5 cotton plants per foot consistently yielded equal or higher than 3 plants per foot across all varieties and a manuscript has been submitted to a journal. Variety, nitrogen rate, and irrigation regimes all individually impacted and interacted to affect lint yield, fiber quality, and seed composition. Cotton grown in twin row production system produced similar yields and fiber quality as cotton produced in the more traditional wide row pattern. The second year of an experiment examining the agronomic and economic value of stacked-gene corn hybrids has been completed with data analyses and manuscript preparation underway. The second year of a study examining the growth rates and nutrient uptake of three soybean cultivars of differing maturity has been completed. Data on photosynthesis has been analyzed and a manuscript submitted for publication. Data on dry matter accumulation is completed and nutrient composition is nearing completion. In a 4-year rotation study, corn yield increased every year following rotation with soybean by 15-31% compared to continuous corn. As a result, net returns were higher in rotated corn compared with continuous corn and the results have been published.
1. Raised vs. flat-bed seedings of soybean in the Mid South. Irrigated soybean grown on raised beds were said to yield more than crops grown of a flat seed bed, but until 2012 this had not yet been confirmed by research. Two commonly grown cultivars, and MG IV and an MG V were produced in 25 cm twin rows spaced 102 cm apart in a two year study by USDA-ARS Research Scientists at Stoneville, MS. Seeding rates of 20, 30, 40, and 50 seeds/m2 were also part of the study. Raised seed beds resulted in an average 195 kg/ha yield increase over flat seed beds across all seeding rates. Seeding rates greater than 30 seed/m2 did not result in increased yields.
2. Cotton irrigation and nitrogen fertilization. Cotton producers are interested in making the most efficient use of their irrigation and nitrogen fertilization inputs because although they are important inputs for a cotton production, these inputs can also be quite expensive. An USDA-ARS scientist at Stoneville, MS, has demonstrated that including irrigation is an important component to ensure the most efficient use of the nitrogen that is applied to cotton. In the 2011 growing season, the lint yield of non-irrigated cotton was not improved when 100 lbs nitrogen/acre was applied over the non-fertilized (858 vs. 813 lbs/acre). However, when irrigation was applied, the 100 lbs N/acre treated yielded 19% greater than the unfertilized (1202 vs. 1013 lbs/acre). 2012 was a wet year so no irrigation effect was detected, but nitrogen fertilization continued to increase yields over the non-fertilized. Fiber quality and seed composition were also affected by the irrigation and nitrogen fertility treatments. Using this information producers will be in a better position to make a more appropriate N fertilization rate decision for a field depending upon the irrigation capabilities for that field.
3. Corn and soybean rotation under reduced tillage management, impacts on soil properties, yield, and net return. Rotating crops has the potential to increase yields without increasing production costs compared to crops grown continuously. Scientists at the USDA-ARS, Crop Production Systems Research Unit in Stoneville, MS, conducted a 4-yr (2007 to 2010) study that examined the effects of rotating corn and soybean under reduced tillage conditions on soil properties, yields, and net return. The six rotation systems: continuous corn (CCCC), continuous soybean (SSSS), corn-soybean (CSCS), soybean-corn (SCSC), soybean-soybean-corn-soybean (SSCS), and soybean-soybean-soybean-corn (SSSC) were used. Field preparation consisted of disking, subsoiling, disking, and bedding in the fall of 2005. After the fall of 2006, the raised beds were refurbished each fall after harvest with no additional tillage operations to maintain as reduced tillage system. The surface 5 cm soil from continuous soybean had higher pH than continuous corn in all four years. Unlike pH, total carbon and total nitrogen were higher in continuous corn compared to continuous soybean. Corn yield increased every year following rotation with soybean by 15-31% compared to continuous corn. As a result, net returns were higher in rotated corn compared with continuous corn. This study demonstrated that alternating between corn and soybean is a sustainable practice with increased net returns in corn.
Pettigrew, W.T. 2012. Photosynthesis and carbon partitioning/source-sink relationships. In D.M. Oosterhuis J. Tom Cothern (ed.) Cotton Flowering and Fruiting. The Cotton Foundation. Cordova, TN. p. 25-34.