Settimi J.R.,Abraham Baldwin Agricultural College |
Sullivan D.G.,Turf Scout LLC |
Strickland T.C.,U.S. Department of Agriculture
Journal of Soil and Water Conservation | Year: 2010
The Conservation Effects Assessment Program Watershed Assessment Study is a joint effort between the USDA Natural Resources Conservation Service (NRCS) and the USDA Agricultural Research Service to evaluate the effectiveness of federally funded conservation programs. In response to this initiative, a 26-year history of NRCS conservation practice placement (1980 to 2006) was evaluated for the Little River Experimental Watershed (LREW) in the southeastern coastal plain of Georgia.To accomplish this task, currently available geographic databases were integrated and queried to assess levels of commonly adopted practices and to evaluate factors affecting practice placement. Databases included (1) USDA NRCS Conservation Practice Database for the LREW, (2) USDA NRCS Soil Survey Geographic Database (SSURGO), and (3) 30 m (98 ft) digital elevation maps. Nearly 50% of all cropland fields in the LREW were delineated as having participated in conservation programs. Practices were predominantly used for water quality and erosion control. Sixty to 65% of the fields (77% of land area) implemented soil erosion and/or water quality control practices in high resource concern areas. Results showed that hydrologie group and proximity to a water body, rather than slope class, were the predominant factors in conservation practice placement. Using a subwatershed database having complete field coverage of four LREW subwatersheds (with and without USDA NRCS assistance), geographic information system databases were queried to evaluate the adoption and placement of erosion control practices that were visible in a 2005 digital orthoquad. Forty-seven percent of all fields in the subwatershed database had implemented visible erosion control-specific conservation practices, and implementation was linearly related to slope class (r2 = 0.64, p < 0.10). Fields identified as having participated in federally funded conservation programs coincided with high resource concern areas 35% of the time.
Toews M.D.,University of Georgia |
Tubbs R.S.,University of Georgia |
Wann D.Q.,University of Georgia |
Sullivan D.,U.S. Department of Agriculture |
Sullivan D.,Turf Scout LLC
Pest Management Science | Year: 2010
BACKGROUND:Thripsare themost consistent insectpests ofseedling cotton inthesoutheastern United States,wheresymptoms can range from leaf curling to stand loss. In a 2 year study, thrips adults and immatures were sampled at 14, 21 and 28 days after planting on cotton planted with a thiamethoxam seed treatment in concertwith crimson clover,wheat or ryewinter cover crops and conventional or strip tillage to investigate potential differences in thrips infestations. RESULTS: Densities of adult thrips, primarily Frankliniella fusca (Hinds), peaked on the first sampling date, whereas immature densities peaked on the second sampling date. Regardless of winter cover crop, plots that received strip tillage experienced significantly fewer thrips at each sampling interval. In addition, assessment of percentage ground cover 42 days after planting showed that therewas more than twice asmuch ground cover in the strip-tilled plots compared with conventionally tilled plots. Correlation analyses showed that increased ground cover was inversely related to thrips densities that occurred on all three sampling dates in 2008 and the final sampling date in 2009. CONCLUSIONS:Growerswhoutilize strip tillageandawinter cover cropcanutilize seedtreatments for mitigation of early-season thrips infestation. © 2010 Society of Chemical Industry.
Strickland T.C.,U.S. Department of Agriculture |
Scully B.T.,U.S. Department of Agriculture |
Hubbard R.K.,U.S. Department of Agriculture |
Sullivan D.G.,TurfScout LLC |
And 5 more authors.
Journal of Soil and Water Conservation | Year: 2015
Although conservation tillage is widely believed to be an agricultural management practice effective for increasing soil carbon (C) accretion and associated soil quality, there is limited research to determine whether conservation tillage increases net C accretion versus simply altering the distribution of C content by soil depth. We implemented conservation farming practices (winter cover cropping plus strip tillage) for a nonirrigated corn (Zea mays L.) production system in the southeastern coastal plain of Georgia, United States, that had been previously managed under a conventional plow and harrow tillage regime. Total soil C and nitrogen (N) were measured on samples collected from 0 to 65 cm (0 to 25.6 in) at 57 sites before and after five years under conservation farming practices. Crop yield, winter and summer aboveground crop biomass production, and biomass C and N content were also measured annually at each site. Soil C increased an average of 20 Mg ha-1 (8.9 tn ac-1; 6 to 62 Mg C ha-1 [2.6 to 27.6 tn C ac-1], depending upon slope position) and was associated with a N increase of 2 Mg ha-1 (0.89 tn ac-1). Although 72% to 80% of the C accretion was in the top 35 cm (13.8 in), 3 to 6 Mg C ha-1 (1.3 to 2.6 tn C ac-1) was accreted from 35 to 65 cm (13.8 to 25.6 in). The soil C accreted during the study amounted to 36% of the net biomass C produced. Corn yield increased 2,200 kg ha-1 (1,964 lb ac-1) depending upon slope position (1,200 to 2,500 kg ha-1 [1,071 to 2,232 lb ac-1]) during the same time. Analysis indicated that soil C content from 15 to 35 cm (5.9 to 13.8 in) was the soil parameter primarily associated with corn yield. Season rainfall from planting to corn silking stage for both corn production years was the lowest in the past 45 years (20 to 25 cm [7.8 to 9.8 in] below the net crop demand) suggesting that soil C-mediated increase in plant-available soil water was a mechanism contributing to improved corn yield. Calculated estimates (from soil clay, sand, and C content) of increased soil water holding capacity suggest that C accretion in the top 35 cm (13.8 in) of soil potentially increased water storage enough to supply up to four days' worth of additional crop water demand. These results indicated that conservation farming practices can increase soil C and N accretion in degraded sandy soils of the humid southeastern United States coastal plain, and that increased soil C may potentially mitigate the deleterious effects of short-term rainfall deficits in nonirrigated production systems.
Ortiz B.V.,Auburn University |
Perry C.,University of Georgia |
Sullivan D.,Turfscout LLC |
Lu P.,University of Georgia |
And 5 more authors.
Journal of Nematology | Year: 2012
Field tests were conducted to determine if differences in response to nematicide application (i.e., root-knot nematode (RKN) populations, cotton yield, and profitability) occurred among RKN management zones (MZ). The MZ were delineated using fuzzy clustering of five terrain (TR) and edaphic (ED) field features related to soil texture: apparent soil electrical conductivity shallow (ECa-shallow) and deep (ECa-deep), elevation (EL), slope (SL), and changes in bare soil reflectance. Zones with lowest mean values of ECa-shallow, ECa-deep, NDVI, and SL were designated as at greater risk for high RKN levels. Nematicide-treated plots (4 rows wide and 30 m long) were established in a randomized complete block design within each zone, but the number of replications in each zone varied from four to six depending on the size of the zone.The nematicides aldicarb (Temik 15 G) and 1,3-dichloropropene (1,3-D,Telone II) were applied at two rates (0.51 and 1.0 kg a.i./ha for aldicarb, and 33.1 and 66.2 kg a.i./ha for 1,3-D) to RKN MZ in commercial fields between 2007 and 2009. A consolidated analysis over the entire season showed that regardless of the zone, there were not differences between aldicarb rates and 1,3-D rates. The result across zones showed that 1,3-D provided better RKN control than did aldicarb in zones with low ECa values (high RKN risk zones exhibiting more coarse-textured sandy soils). In contrast, in low risk zones with relatively higher ECa values (heavier textured soil), the effects of 1,3-D and aldicarb were equal and application of any of the treatments provided sufficient control. In low RKN risk zones, a farmer would often have lost money if a high rate of 1,3-D was applied. This study showed that the effect of nematicide type and rate on RKN control and cotton yield varied across management zones (MZ) with the most expensive treatment likely to provide economic benefit only in zones with coarser soil texture. This study demonstrates the value of site specific application of nematicides based on management zones, although this approach might not be economically beneficial in fields with little variability in soil texture. © The Society of Nematologists 2012.
Davis R.F.,U.S. Department of Agriculture |
Aryal S.K.,University of Georgia |
Perry C.D.,University of Georgia |
Sullivan D.G.,TurfScout Inc. |
And 5 more authors.
Crop Protection | Year: 2013
Nematode management zones (MZs) based on soil electrical conductivity (EC, a proxy for soil texture) have not been published for Rotylenchulus reniformis. We tested 1) whether R.reniformis levels and the amount of damage caused to cotton differed among MZs, 2) if the relative effectiveness of nematicides differed among MZs, and 3) whether the prevalence of Pasteuria sp. on R.reniformis differed among MZs and nematicide treatments. A field was divided into three MZs where MZ3 had sandier soil than MZ1 or MZ2, which were the same, and MZ2 had higher elevation than MZ1 or MZ3, which were the same. Levels of R.reniformis near planting in plots not receiving nematicide averaged 1342 (per 150cm3 soil) in 2008, 610 in 2009, and 869 in 2010. Both soil texture and elevation influenced R.reniformis population levels with greater reproduction in finer-textured soil and reduced R.reniformis levels at higher elevation. Treatment effects on R.reniformis levels were the same in all MZs (no MZ×treatment interactions). The effects of texture and elevation on yield were similar to the effects on nematode levels. We observed endospores of Pasteuria sp., a bacterial parasite of nematodes, on R.reniformis at the field site used for this study. Pasteuria sp. generally had greater spore attachment to juvenile R.reniformis than to adults with no differences among MZs in percentage of nematodes with endospores, but the number of spores per nematode was lower in MZ3, which had the greatest sand content. The percentage of R.reniformis with endospores and the number of attached endospores were reduced by 1,3-dichloropropene+aldicarb. We documented that R.reniformis levels are affected by modest differences in soil texture and elevation, but levels of R.reniformis were above the action threshold in all MZs, therefore a uniform rate of nematicide would have been recommended and there would have been no cost savings from utilizing MZs in this field. © 2013.
Kowalewski A.R.,Oregon State University |
Schwartz B.M.,University of Georgia |
Grimshaw A.L.,University of Georgia |
Sullivan D.G.,TurfScout LLC |
And 5 more authors.
Crop Science | Year: 2013
Traffic simulators are often utilized when researching turfgrass wear tolerance and recovery. However, the availability of a durable traffic simulator capable of producing dynamic force is limited. Therefore, the objectives of this research were to: (i) evaluate a novel traffic simulator with improved durability and capable of producing dynamic force and (ii) evaluate the biophysical effects of the traffic simulator on a native soil turfgrass system. The Baldree traffic simulator is a modified Ryan GA 30 (Jacobsen, A Textron Company, Charlotte, NC) riding aerification unit, equipped with fabricated, spring loaded steel plate feet studded with screw in cleats. The effects of this unit on a 'Tifway' bermudagrass [Cynodon dactylon (L.) Pers. × C. transvaalensis Burtt-Davy] system established on a Tifton loamy sand (fine-loamy, kaolinitic, thermic Plinthic Kandiudults) were evaluated at the Coastal Plains Experiment Station, Tifton, GA. Factors included location (1 and 2) and traffic rate (0, 12, and 24 passes applied over a 6 wk period). Field data included soil bulk density, turf density, and percent green turf cover. An in-ground force plate at the McPhail Equine Performance Center, East Lansing, MI was used to quantify vertical and net shear ground reaction force produced by the Baldree traffic simulator when operated in the forward and backward direction. The Baldree traffic simulator produced more cleat marks per pass than the Brinkman and Cady traffic simulators. At the low traffic rate the Baldree traffic simulator increased soil bulk density, while turf density and percent green turf cover decreased; therefore, the tool can be used to simulate heavy traffic conditions with a minimum number of passes. © © Crop Science Society of America All rights reserved.
Ritchie G.L.,University of Georgia |
Sullivan D.G.,TurfScout LLC |
Vencill W.K.,University of Georgia |
Bednarz C.W.,Texas Tech University |
Hook J.E.,University of Georgia
Crop Science | Year: 2010
Vegetation indices based solely on visible reflectance may simplify and decrease the cost of crop growth estimates compared to visible and near-infrared (NIR) indices. Ground-based and aerial visible and visible/NIR vegetation indices based on aerial images were compared for sensitivity to ground cover fraction (GCF) of cotton (Gossypium hirsutum L.) under four irrigation treatments in 2004 and five treatments in 2005 and 2006. In-season cotton imagery was collected using an unmodified Nikon COOLPIX 4300 camera and a COOLPIX 4300 camera modified for NIR imaging attached to a tethered blimp. GCF imagery was collected at 45 to 60 m and compared with normalized difference vegetation index (NDVI) and green/red ratio values from imagery collected at 180 to 250 m. Ground-based (1.5 m) spectrometer NDVI measurements using multiple spectral regions were also evaluated. Spectrometer (r2 = 0.40 to 0.80) and camera (r2 = 0.68 to 0.90) indices were highly correlated with season-wide GCF between fractions of 0.20 and 0.80 and were sensitive to irrigation treatments. Camera green/red ratio was linearly correlated with GCF throughout the 3 yr. The pooled comparison for the 3 yr was strongly linear (r2 = 0.86). Our results suggest that the green/red ratio index might allow quick, simple, and accurate crop growth estimates for production. © Crop Science Society of America.