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The dwarf red cotton (Gossypium hirsutum L.) variety CSA0107 B2RF (Monsanto Cotton States) has a growth habit that generally prevents canopy closure in conventional row (CR) spacings, suggesting that ultra-narrow row (UNR) systems would be advantageous to yield in this variety. The study objectives were to compare lint yield of both a red dwarf and a normally-statured cotton variety in a UNR and a CR system. The location was the LSU Agricultural Center's Northeast Research Station, Saint Joseph, LA. Each system was planted on a wide raised bed, with 4 rows (averaging 20 inches wide) per bed in the UNR treatments and 2 rows (40 inches wide) per bed in the CR treatments. Plant populations were elevated by approximately 50 percent in UNR treatments. Few treatment effects were observed on lint percentage and fiber quality. Lint yield was significantly decreased by the UNR system relative to the CR, although the difference between means was small. Lint yield was significantly and substantially lower for the dwarf red variety than for Stoneville 4554 B2RF. Despite the benefits of the UNR system to canopy closure in the dwarf red variety, the lint yield of each variety responded similarly to row spacing and the interaction between these factors was not significant. The data suggest that reduced lint yields of the dwarf red variety in CR systems may originate at least partially with factors other than a lack of canopy closure. The UNR system was not beneficial to yield in any variety. [ABSTRACT FROM AUTHOR]

US Cotton growers are adopting COTMAN, a COTton MANagement system used to monitor crop development and aid in making end-of-season decisions. Currently, research-based decision guides have been developed to aid in identifying the last effective boll population and determining the optimal dates for safe termination of insect control and application of defoliants based on the occurrence of a first-position white flower five nodes below the terminal (NAWF=5). Another area of cotton production that may benefit from COTMAN is the decision of when to stop irrigating the crop. The objective of this research was to investigate a crop-based recommendation for timing the final irrigation on cotton. Data sets from 26 Mid-South cotton irrigation termination studies during the 2000 through 2005 growing seasons, a total of 432 data points, were fit to a quadratic equation. However, the residual yield values were correlated due to the fact that different studies had quite different yields. To avoid the serial correlation, data from each study were normalized such that the average lint yield for the study was adjusted to 1,000 lb/acre and again fit to a quadratic equation. The resulting equation had a maximum yield of 1021 lb lint/acre at 692 DD60 after NAWF=5. At NAWF=5, generally associated with physiological cutout, the yield was 963 lb lint/acre, 58 lb lint/acre below the maximum. Additional work will be necessary before a recommendation for irrigation termination can be added to COTMAN, including investigating: functions other than the quadratic; the possibility of differences in the northern and southern portions of the Mid-South; and any possible effects on fiber quality, particularly micronaire, and crop maturity. [ABSTRACT FROM AUTHOR]

Changes in commodity prices from year to year and the proven benefits of crop diversification suggest that selected multi-cropping practices may enhance overall farm profitability. Rotational crop sequences often increase the yields of the rotated crops, an effect that may be more pronounced when yields are limited by specific problems that are ameliorated by the cropping sequences. Nematode infestations, soil-borne diseases and weed infestations are examples of specific yield limiting problems that require rotations with alternative crops to maintain or increase cotton yield. The advent of high yielding early maturing wheat varieties, insect-resistant cotton varieties and boll weevil eradication has opened up new possibilities for diversifying crop selection while implementing Best Management Practices (BMPs) in the Mid-South. A wheat winter cover crop grown as a green manure increases the yield of the following cotton crop and is an important component of BMPs that will likely become part of nutrient management plans of farms in the Mid-South. Wheat residue is beneficial because it reduces erosion, conserves soil water, improves soil quality and protects cotton seedlings from abiotic damage. Used as a green manure, wheat growth is terminated before grain fill (Zodaks Growth Stage 40-59), so the summer crop can be planted in a timely manner. The farmer gains no cash benefit from the wheat crop. With new technology, it is increasingly practical to harvest a wheat cash crop and follow with a high-yielding summer crop. High yielding fields are generally well drained and many are irrigated, which further enhances the feasibility of successful double-crop wheat + summer crop production. Other BMP systems in which cotton, corn, soybean and grain sorghum are grown in rotations are beneficial for soil improvement and disease, nematode and weed control. Profitability of alternative cropping systems versus continuous monocropping is determined by the magnitude of crop responses and, perhaps more importantly, by commodity prices of the included crops. Multicrop sequences can have significant yield benefits but may be no more profitable than monocropping if alternative crops have low profitability. When returns from alternative crops are lower than for cotton, the yield increases gained from diversified systems must be large enough to offset the reduced income from the alternative crop. The objective of this paper is to use ongoing rotation and cropping systems experiments with emphasis placed on BMPs (minimum tillage and crop and cover crop residues for water quality protection) to compare continuous monocrop cotton with multicrop sequences to determine if diversification increases yields and profitability. [ABSTRACT FROM AUTHOR]

At the present time, there is lack of data on daily cotton evapotranspiration (ET) in relation to weather conditions and growth stage in Louisiana. To allow this data to be obtained, two weighing lysimeters were installed at the LSU AgCenter Northeast Research Station, Saint Joseph, LA. A two-tank design was used, with the inner tanks having dimensions of 59 inches in length and depth, and 40 inches in width. Soil was excavated from the installation site and replaced in the lysimeters in layers. A datalogger was placed between the lysimeters to record load cell weights. [ABSTRACT FROM AUTHOR]

Soil tests have not been shown to be predictive of crop N fertilizer requirements in Louisiana, creating uncertainty as to optimal N fertilizer rates for cotton (Gossypium hirsutum L.) production. If remotely-sensed cotton canopy reflectance characteristics are indicative of cotton crop N status, they may allow in-season N applications that closely approximate actual crop requirements in the specific location sensed. Our objective was to determine whether lint yields were related to remotely sensed normalized difference vegetation index (NDVI) measurements under a series of N fertilizer rates. Experiments were established in 2008 and 2009 on Gigger silt loam at the LSU AgCenter Macon Ridge Research Station in Winnsboro, LA and on Sharkey clay at the LSU AgCenter Northeast Research Station in Saint Joseph, LA. An additional location was established on a Commerce silty clay loam at the Northeast Research Station in 2009. The experimental designs were randomized complete blocks with factorial arrangements of early-season N rates (0 to 150 lb N/A in 30-lb increments) and plant growth regulator (PGR) rates (applied or not applied). Two additional treatments with midseason N applications were included as well. Hand-held Greenseeker™ NDVI sensor readings were made at four growth stages: early square, early bloom, two weeks after early bloom, and four weeks after early bloom. Using all data points from the factorial early-season N rate and PGR treatments, models were fit relating cotton lint yield to NDVI readings from single sensing periods. Variants of NDVI used as explanatory variables were unadjusted NDVI and NDVI further normalized by division by days after planting (DAP) or cumulative growing degree days after planting (GDD). Best-fit models were considered to be those with highest coefficient of determination (R²). When the 2008 data were considered alone, highest model R² values were generally associated with NDVI when sensed two weeks after planting. Unadjusted NDVI was best related to lint yield by a power model with R² = 0.40. When divided by DAP, NDVI was best related to lint yield by an exponential model with R² = 0.74. For 2008 and 2009 data combined, relationships of lint yield and NDVI were strongest four weeks after early bloom. The best fits were found from exponential models with R² of 0.33, 0.20, and 0.50, respectively, for models with explanatory variables of unadjusted NDVI, NDVI divided by DAP, or NDVI divided by GDD. In both years, but particularly in 2008, weather-related factors strongly influenced yields of one or more locations. Because this effect was independent of N rate and in-season NDVI, typical relationships between NDVI and lint yield may have been altered. In summary, in many cases normalization of NDVI by DAP or GDD was effective in increasing the degree to which lint yield could be predicted by NDVI. Early-season relationships between NDVI and lint yield were not strong by the means of analysis discussed here. However, finding such relationships is critical to a system which guides in-season cotton N fertilizer applications through canopy NDVI. Further analyses of the data, perhaps including the use of relative lint yields to adjust for test-wide lint yield influences, may be warranted. [ABSTRACT FROM AUTHOR]

Cotton (Gossypium hirsutum L.) is an important commercially grown crop in the northeast part of Louisiana. Research-based information is available on some aspects of irrigation but there is a lack of information on cotton water use in this region. Our objectives were to develop locally-based crop coefficients (Kc) to estimate cotton water use. Crop coefficients (Kc) are ratios of crop evapotranspiration (ETc) at a given stage of growth to reference evapotranspiration (ETo) calculated from weather measurements made over a reference grass surface. An experiment was conducted at the Northeast Research Station, Saint Joseph, LA in 2009. Cotton (Stoneville ST 5458 B2RF) was planted in peat pots on April 27-29, which were transplanted onto paired weighing lysimeters and their immediate surroundings on May 8. The field surrounding the lysimeters was planted on April 25-27. Changes in mass (kg) on a daily basis for both lysimeters were recorded using a Campbell Scientific CR3000 data logger from August 5 onward. These changes in mass were converted to equivalent water depths (mm) and represent ETc. For measurement of ETo, a reference weather station was completed. Bermuda grass (Cynodon dactylon L.) was planted on April 17 as a reference surface. An area of 102 m by 102 m was demarcated and divided into 3 bays each of 34 m width to allow intermittent shallow flood irrigation. A tower of 10 m height was instrumented to allow an array of measurements including wind speed, solar radiation, air temperature, and relative humidity as required to calculate ETo from the American Society of Civil Engineers (ASCE) Standardized Reference Evapotranspiration Equation. These weather parameters were recorded using a CR3000 data logger. Adequate lysimeter soil water was maintained during the data collection period. Apparent residual nitrogen caused relatively vigorous plant growth on the lysimeters, which was countered by a plant growth regulator application on August 14 and by crossing stems of lysimeter plants on August 22. Values of ETc and ETo were within ranges of 4.31 mm to 7.06 mm and 3.57 mm to 5.01 mm, respectively, during the period from August 7 to September 9. Single daily measurements of Kc ranged from 1.20 to 1.50 during this period with the exception of two outliers. Crop coefficients did not decline toward the end of this period possibly due to delayed canopy senescence caused by residual nitrogen in the lysimeters. In summary, the majority of work on the facilities for this project was finished and preliminary late season crop coefficients were determined. [ABSTRACT FROM AUTHOR]

After a number of years of using the Bray 2 test, Louisiana adopted the Mehlich 3 test for soil P. Conversion of Mehlich 3 soil test values to equivalent Bray 2 values, using a relationship derived from the performance of both soil tests on samples of a range of soils, has since proved to be problematic for at least some soils in the Commerce series. A direct calibration of Mehlich 3 soil test P to crop responses to P fertilizer is needed. Randomized complete block designs were used in two studies on soils in the Commerce series at the LSU AgCenter Northeast Research Station, Saint Joseph, LA. Each included 10 treatments. Treatments 1-5 were comprised of rates of triple superphosphate equivalent to 0, 30, 60, 90, and 120 lb P2O5/A, respectively, applied only in 2007. Treatments 6-10 were identical rates applied only in 2008. All P treatments were broadcast in the spring, prior to planting, and incorporated. Study 1 was planted to cotton in 2007 and to corn in 2008. Study 2 was planted to corn in 2007 and to cotton in 2008. In general, the soil in both studies was coarse textured, with the exception of one replication in Study 2, where hand-judged textures were mostly silty clay loam. Average pH values were 5.6 and 5.8, respectively in Study 1 (June 2007, check plots) and Study 2 (April 2008, all plots). In Study 1, June 2007 check plot 0-6" Mehlich III soil P values ranged from 11.9 to 22.8 ppm. Lint yield did not differ among treatments, and on an individual-plot basis for those plots soil sampled (all treated plots plus two untreated per replication), showed little evidence of relationship to postharvest 0-6" Mehlich III P. Lint yield was also unrelated to postharvest 6-12" Mehlich III P in a reduced subset of treatments. In Study 2, April 2008 (prior to fertilizer treatment application and planting) 0-6" Mehlich III soil P values, from all plots, ranged from 19.8 to 27.4, with no significant differences among treatments. Lint yield, which was depressed and variable because of severe weather events, did not differ significantly among treatments. In individual plot data, lint yield showed little evidence of relationship to preplant or postharvest Mehlich III soil test P values from either 0-6" or 6-12" depths. In summary, lint yield had little relationship to preseason or postseason Mehlich 3 soil test P at either sample depth, although adverse weather conditions in 2008 affected yields. The preliminary results suggest that on the soils in these studies, P may not be yield limiting for cotton. Mehlich 3 soil test P critical levels for cotton on this soil may be lower than the soil test values obtained to date. [ABSTRACT FROM AUTHOR]

An abstract of the article "The Impact of Planting Date on Fiber and Yarn Quality," by Gayle H. Davidonis, Ernest L. Clawson and Devron P. Thibodeaux is presented.

An abstract of the article "Weighing Lysimeters in Northeast Louisiana: First Year's Experience" is presented.

An abstract of the study "Effects of Planting Date on Micronaire and Fiber Maturity Distributions," by Gayle H. Davidonis, Donald J. Bonquet, and Ernest L. Clawson is presented.

An abstract of the article "Timing of Irrigation Termination on Sharkey Clay in Northeast Louisiana," by Ernest L. Clawson and Alphonse B. Coco is presented.

An abstract of the article "Comparison of Sampling Methods for Lint Percent and Fiber Quality in the LSU AgCenter Official Cotton Variety Trials," by Ernest L. Clawson and Alphonse B. Coco, is presented.

An abstract of the article "Planting Date and Variety Effects on Cotton Yield and Maturity in Northeast Louisiana," by Ernest Clawson, Alphonse B. Coco, and Donald J. Boquet, is presented.