Charles H. Burmester

Cotton response to in-row subsoiling and potassium fertilizer placement in Alabama

In the USA a suggested method for correcting late season K deficiencies in cotton (Gossypium hirsutum L.) is by in-row deep placement of K fertilizer. Experiments were conducted on three Alabama soils (southeastern USA) for 3 years to evaluate cotton response to K fertilizer when surface broadcast with and without in-row subsoiling (to 38 cm depth) or deep placed in the in-row subsoil channel. Potassium was applied at rates ranging from 0 to 84 kg K ha−1. Deep placement was achieved with a fertilizer applicator developed to distribute dry fertilizer at three depths down the back of the subsoil shank. All three soils also had deep placement treatments of 1680 kg ha−1 agricultural limestone with and without 84 kg K ha−1. Soils were an Emory silt loam (fine-silty, siliceous Fluventic Umbric Dystrochrepts), a Norfolk sandy loam (fine-loamy, siliceous Typic Kandiudults), and a Lucedale sandy clay loam (fine-loamy, siliceous Rhodic Paleuduts). All three soils had medium soil test K concentrations in the plow layer and medium or low concentrations of K at greater depths. The Norfolk soil had a well-developed traffic pan and in-row subsoiling increased seed cotton yields by an average of 22% during the 3 years of the study. Cotton responded to K fertilization in 2 out of 3 years at each location (6 out of 9 site-years) regardless of the method of K application. Annual applications of 84 kg K ha−1 increased 3 year average seed cotton yields by 17%, 10% and 19% on the Emory, Norfolk and Lucedale soils, respectively. Deep placement of agricultural limestone with or without K fertilizer for cotton did not increase cotton yields.

Conservation Tillage, Rotations, and Cover Crop Affecting Soil Quality in the Tennessee Valley: Particulate Organic Matter, Organic Matter, and Microbial Biomass

Abstract The impact of conservation tillage, crop rotation, and cover cropping on soil‐quality indicators was evaluated in a long‐term experiment for cotton. Compared to conventional‐tillage cotton, other treatments had 3.4 to 7.7 Mg ha−1 more carbon (C) over all soil depths. The particulate organic matter C (POMc) accounts for 29 to 48 and 16 to 22% of soil organic C (SOC) for the 0‐ to 3‐and 3‐ to 6‐cm depths, respectively. Tillage had a strongth influence on POMc within the 0‐ to 3‐cm depth, but cropping intensity and cover crop did not affect POMc. A large stratification for microbial biomass was observed varing from 221 to 434 and 63 to 110 mg kg−1 within depth of 0–3 and 12–24 cm respectively. The microbial biomass is a more sensitive indicator (compared to SOC) of management impacts, showing clear effect of tillage, rotation, and cropping intensity. The no‐tillage cotton double‐cropped wheat/soybean system that combined high cropping intensity and crop rotation provided the best soil quality.

Starter fertilizer and the method and rate of potassium fertilizer effects on cotton grown on soils with and without winter grazing by cattle

Abstract A three‐year field study was conducted on a Decatur silt loam (clayey, kaolinitic, thermic Rhodic Paleudult) in North Alabama. The objective of the study was to evaluate the effects of winter grazing by cattle on the potassium (K) and starter fertilizer needs of cotton (Gossypium hirsutum L.) the following season. Grazed and non‐grazed treatments were established by planting a wheat (Triticum aestivum L.) cover crop in the fall and allowing cattle to graze half of the treatment area for 35 to 65 days in late winter‐early spring. After grazing, the grazed and non‐grazed wheat was killed and cotton was planted using a strip‐tillage system. Test areas had medium to high soil test ratings for K. Fertility treatments consisted of three rates of K (0, 37, and 74 kg K ha‐1), three methods of K application (surface broadcast; in‐row, band application at a depth of 30.5 cm; and surface banding using a spacing of 50.8 cm) and two rates of starter fertilizer (no starter and 168 kg#lbha‐l of a liquid 15–15–0...

Potassium fertilization effects on yield and longevity of established alfalfa

Abstract Limited information is available which describes the response of established alfalfa (Medicago sativa L.) to topdressing applications of K fertilizer in the Southeastern United States. Field experiments were conducted for three years to determine alfalfa response to rates and time of K application. The experiments were established in two‐year old stands of alfalfa on a Decatur silty clay loam (clayey, kaolinitic, thermic Rhodic Paleudults) and a Hartsells fine sandy loam (fine loamy, siliceous, thermic Typic Hapludults) located in northern Alabama. Potassium as KCl was broadcast in the spring prior to regrowth. For split application treatments, the K was applied in early spring and after the second cutting. Annual total K rates ranged from 56 to 596 kg/ha. Potassium fertilization maintained alfalfa stand density on both soils, but the experiment on the Decatur soil was discontinued after two years due to severe stand loss when the lowest rate of added K was used. Alfalfa yields were increased by ...

Subsurface Drip Irrigation Placement and Cotton Irrigation Water Requirement in the Tennessee Valley

Fluctuations in dryland cotton yield in the Tennessee Valley region of northern Alabama are common and are usually related to irregular drought periods during the growing season. Subsurface drip irrigation (SDI) has gained popularity as a water delivery system for small, irregular-shaped cotton fields. A seven-year study was conducted with the objective to determine the response of seed cotton yield to SDI tape orientation relative to crop row direction and different irrigation rates under dryland conditions of the Tennessee Valley. Seven treatments were tested in a randomized incomplete block design which consisted of three irrigation treatments (33%, 66%, and 99% pan evaporation), two SDI tape orientations (parallel and perpendicular), and a dryland control. All SDI treatments produced yields significantly higher than non-irrigated, dryland cotton in four out of seven years. Maximum yield was obtained at a median pan evaporation water replacement value of 74%. No statistical differences were observed between SDI tape orientations on seed cotton yield in all years except in 1999 when parallel out yielded perpendicular at lower irrigation rates. Results confirm the long-term efficacy of supplemental irrigation to increase seed cotton yield irrespective of SDI tape placement during sporadic periods of drought. These results are applicable only for fields with the same soil type or with similar water movement characteristics.

Precision Fertilization Using Sub-Surface Drip Irrigation (SDI) for Site-Specific Management of Cotton

Results are presented for a first year study that investigates different fertigation treatments for cotton produced using precision agriculture in the Tennessee Valley of Alabama. The study evaluates the timing and placement of soluble nitrogen and potassium (K2O) fertilizer on cotton using four different fertigation treatments and a non-fertigated control irrigated with sub-surface drip irrigation (SDI) tape. The pressure-compensating SDI product was installed in 2005 using an auto-guidance system to ensure all tape runs are precisely located parallel and 80 inches apart. The experimental plots consist of four replications of five eight-row treatments that compare four fertigation management scenarios and one conventional side-dress treatment. Each of the resulting twenty treatment plots has eight 360-foot rows of cotton on 40-inch row spacing, with SDI tape buried approximately 15 inches between every other row of cotton. The response to treatments is quantified by measuring yield, quality, and nutrient uptake of the cotton. Results show that fertigated cotton yields were higher than the non-fertigated control, with higher yields observed in the three treatments receiving fertigation within 50 days of square. The two highest yielding treatments also received 20 and 40 pounds, respectively, of pre-plant surface nitrogen and potassium. Fertigated cotton yields averaged 3.0 bales per acre compared with 2.6 bales per acre for the non-fertigated control and 2.2 bales per acre in a nearby sprinkler-irrigated study.

Sub-surface Drip Irrigation-Fertigation for Precision Management of Cotton

Four years of field research are presented for a subsurface drip irrigation study installed at the Tennessee Valley Research and Extension Center in northern Alabama in 2006. Study objectives are to evaluate the effect of four precision fertigation management scenarios and a non-fertigated control on cotton yield, nutrient uptake, and lint quality. Approximately 7,500 feet of SDI tape and four positive displacement liquid fertilizer injectors were used to evaluate four replications of five nutrient timing treatments in a randomized complete block design. Each of the twenty treatment plots was made up of eight, 345-foot rows of cotton on 40-inch row spacing, with drip tape between every other row of cotton. In 2006, fertigated cotton yields were significantly higher than the surface-applied control. In 2007 and 2008, however, yield in surface-applied control was significantly higher than the fertigated treatments. Higher non-fertigated control versus fertigated yields in 2007 and 2008 were possibly due to beneficial downward movement of surface-applied fertilizer as a result of early season rainfall in 2007 and the leaching of fertigated nutrients beyond roots zone in 2008 after heavy seasonal rainfall. In 2009, overall yields in all treatments were lower and there was no significant difference between treatments. Fertigated cotton yields averaged 3.0, 2.9, 3.5, and 2.0 bales per acre and the control yields averaged 2.7, 3.1, 3.9, and 1.7 bales/acre in 2006, 2007, 2008, and 2009, respectively. Generally, surface sidedressing enhanced nutrient uptake over fertigation but none had a direct effect on cotton fiber quality. Results of this study indicate that surface sidedressing and fertigation are not mutually exclusive under rainfed cotton production; and observed response to SDI fertigation appears related to the amount and distribution of rainfall during the growing season.