Progress 10/01/04 to 09/30/10
Outputs
OUTPUTS: Cotton was grown no-till from 2005 through 2009 and conventional tillage was used in 2010. Average lint yield responded quadratically to N rates from 0 to 120 lb N/acre with maximum yield observed near 80 lb N/acre. Average yield for the years 2005-2010 ranged from 766 lb/acre with no N up to 1134 lb/acre with 80 lb N/acre. Yield declined to 1011 lb/acre at the greatest fertilizer N rate of 120 lb N/acre. For the past two years, detection of N stress at early square has been possible using the red-edge inflection point calculated from crop reflectance data collected with a tractor mounted spectrometer. No-till cotton dependency on soil test K only across a three year period demonstrated a decline in yield as soil test K was reduced. A mid- to full-season variety, maintained the greatest yields across all soil test K levels each year. This suggests that root function may be maintained for a longer period in this longer season variety than early maturing varieties which may experience earlier root senescence. The early- through mid-maturity varieties all responded similarly to soil test K and all varieties showed a dramatic decline in yield with depletion of soil test K. PARTICIPANTS: Nothing significant to report during this reporting period. TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Continued maximum no-till lint yield production at a rate of 80 lb N/acre emphasizes the possibility of reducing fertilizer N usage in cotton production in Mississippi without sacrificing lint yield. Development of a canopy reflectance model relative to available soil N will provide growers with a tool to optimizing nutrient management on spatially variable alluvial soils. Variety yield response to residual soil test K levels emphasizes the importance of soil K levels and how these levels impact overall yield. A dramatic decline in lint yield with reliance on only residual soil test K levels as might occur during periods of high K fertilizer prices, emphasizes the importance of continued fertilization, especially in conservation tillage systems such as no-till.
Publications
- Booker, B., and J.J. Varco. 2010. Variety and soil test potassium effects on cotton nutrition and lint yield. p. 1474-1479. Proc. Beltwide Cotton Conference, 4-7 Jan. New Orleans, LA.
- Raper, Tyson B., Jac J. Varco, and Brennan Booker. 2010. Sensor based prediction of cotton growth, leaf nitrogen, and biomass nitrogen. p. 1488-1500. Proc. Beltwide Cotton Conference, 4-7 Jan. New Orleans, LA. Raper, Tyson B., Jac J. Varco, and Brennan Booker. 2010. Comparison of three commercially available crop sensors utilizing NDVI for monitoring cotton growth and nitrogen status. p. 1467. Proc. Beltwide Cotton Conference, 4-7 Jan. New Orleans, LA.
- Varco, Jac J. 2010. Crop reflectance as an indicator of nitrogen availability and fertilizer needs to maximize profitability in cotton production. p. 46-51. Proc. Beltwide Cotton Conference, 4-7 Jan. New Orleans, LA.
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Progress 01/01/09 to 12/31/09
Outputs
OUTPUTS: In the fifth year of no-till cotton, lint yield responded quadratically to N rates from 0 to 120 lb N/acre. Yield ranged from 409 lb/acre with no N up to 624 lb/acre with 80 lb N/acre. Yield declined to 475 lb/acre at the greatest fertilizer N rate of 120 lb N/acre. Excessive rainfall in Sept.-Oct. caused hard lock and yield loss. In the third year of a variety by soil test K level factorial field experiment, lint yield response to residual effects of soil K levels was determined. A full season variety, DP 555 was the highest yielding variety with a yield of 650 lb/acre at a soil test K level of 191 lb K/acre. The earliest maturing variety, DP444 yielded 157 lb/acre at a soil test K of 169 lb K/acre and 489 lb/acre at a soil test K of 211 lb K/acre. These results stress the importance of soil test K levels and how residual soil K influences yield. PARTICIPANTS: Nothing significant to report during this reporting period. TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Continued maximum no-till lint yield production at a rate of 80 lb N/acre emphasizes the possibility of reducing fertilizer N usage in cotton production in Mississippi without sacrificing lint yield. Variety yield response to residual soil test K levels emphasizes the importance of soil K levels and how these levels impact overall yield.
Publications
- No publications reported this period
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Progress 01/01/08 to 12/31/08
Outputs
OUTPUTS: In the fourth year of no-till cotton, lint yield responded quadratically to N rates from 0 to 120 lb N/acre. Yield ranged from 722 lb/acre with no N up to 1048 lb/acre with 80 lb N/acre. Yield declined to 870 lb/acre at the greatest fertilizer N rate of 120 lb N/acre. In the second year of a variety by soil test K level factorial field experiment, lint yield response to residual effects of soil K levels was determined. A full season variety, DP 555 was the highest yielding variety with a yield of 672 lb/acre at a soil test K level of 261 lb K/acre. The earliest maturing variety, DP444 yielded 107 lb/acre at a soil test K of 189 lb K/acre and 607 lb/acre at a soil test K of 282 lb K/acre. These results stress the importance of soil test K levels and how residual soil K influences yield. PARTICIPANTS: Nothing significant to report during this reporting period. TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Continued maximum no-till lint yield production at a rate of 80 lb N/acre emphasizes the possibility of reducing fertilizer N usage in cotton production in Mississippi without sacrificing lint yield. Variety yield response to residual soil test K levels emphasizes the importance of K levels in the soil and how these levels impact overall yield.
Publications
- Varco, Jac J., and C. Owen Gwathmey. 2008. Cotton Response to K as influenced by tillage, variety, and soil. p. 1573-1577. Proc. 2008 Beltwide Cotton Conference, 8-11 Jan. 2008. Nashville, TN.
- Varco, Jac J. 2008. Crop reflectance based fertilizer nitrogen management for improved nitrogen use efficiency in cotton. p. 2-5. Proc. 2008 Southern Plant Nutrient Management Conference, 4-5 Nov. 2008. Olive Branch, MS.
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Progress 01/01/07 to 12/31/07
Outputs
OUTPUTS: In the fourth year of no-till cotton production, lint yield response to residual effects of K, Mg, and S fertilization at varying rates applied in the crop years 2004-2006 were determined. Lint yield increased quadratically from 909 lb/acre to 1211 lb/acre with residual K rates from 0 to 90 lb K/acre. These results stress the importance of fertilization in building up soil test K and the magnitude of the response which can be expected, especially in a dry year such as 2007. Response to residual Mg and S rates was inconsistent. In the third year of no-till cotton, lint yield responded quadratically to N rates from 0 to 120 lb N/acre. Yield ranged from 734 lb/acre with no N up to 1182 lb/acre with 80 lb N/acre. Yield declined to 1098 lb/acre at the greatest N rate of 120 lb N/acre. PARTICIPANTS: No Participant information reported. TARGET AUDIENCES: No Target Audiences information reported. PROJECT MODIFICATIONS: No Project Modifications information reported.
Impacts
Residual response to K in the fourth year of continous no-till cotton emphasizes the importance of not only fertilization for an immediate response, but also residual benefits that must be considered in the overall evaluation of fertilizer economics. Continued maximum no-till lint yield production at a rate of 80 lb N/acre emphasizes the possibility of reducing fertilizer N usage in cotton production in Mississippi without sacrificing lint yield.
Publications
- Varco, Jac J., Robert E. Earnest, and Jimmy D. Johnson. 2007. Urease Inhibitor(Agrotain) Effects on N-Use Efficiency in No-Till Cotton. p. 1984-1987. Proc. 2007 Beltwide Cotton Conference, 10-12 Jan. 2007. New Orleans, LA.
- Varco, Jac J. 2007. Basis for Adopting Variable Rate Nitrogen Fertilization to Maximize Profit and Minimize Environmental Degradation. p. 1290-1295. Proc. 2007 Beltwide Cotton Conference, 10-12 Jan. 2007. New Orleans, LA.
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Progress 01/01/06 to 12/31/06
Outputs
Addition of the urease inhibitor NBPT to broadcast urea resulted in an increase in fertilizer N recovery by no-till cotton of 6.5 percent when compared to untreated urea and 9.0 percent for surface dribbled liquid urea ammonium nitrate (UAN) with NBPT compared to untreated UAN. Treated urea performed most similarly to broadcast ammonium nitrate. Nitrogen recovery for surface dribbled UAN treated with NBPT was comparable to soil incorporation of UAN. For the third continuous year of no-till cotton, lint yield responded quadratically to applied K and S rates. The response to applied K rates provides more evidence as to the importance of this nutrient in no-tillage cotton, especially in dry years. The response to S suggests mineralization from soil organic matter was slowed by the dry conditions.
Impacts
Improved N-use efficiency from urease inhibitor treated urea sources will partially offset rising fertilizer N costs, provide a more acceptable substitute for ammonium nitrate, and reduce ammonia emissions to the atmosphere from this N source. Response to K and S during the third year of continous no-till cotton emphasizes changing nutrient supply as soil chemical, biological, and physical properties evolve in a no-till system and the importance of these two nutrients to maintaining productivity.
Publications
- Earnest, Robert E., and Jac J. Varco. 2006. Fertilizer nitrogen source and placement, and Agrotain effects on no-till cotton N-use-efficiency. p. 2105-2108. Proc. 2006 Beltwide Cotton Conference, 3-6 Jan. 2006. San Antonio, TX.
- Varco, Jac J., and Robert E. Earnest. 2006. On-the-go prediction of cotton plant height and leaf nitrogen concentration. p. 2122-2127. Proc. 2006 Beltwide Cotton 3-6 Jan. 2006. San Antonio, TX.
- Oldham, J.L., R.E. Earnest, J.J. Varco, and P. Reid-Rhoades. 2006. Effective N management with increasing economic and environmental challenges in Mississippi. p. 60-65 In Carl Crozier (ed.) Proc. Southern Plant Nutrient Management Conference 3-4 Oct. 2006. Olive Branch, MS. The Noble Foundation.
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Progress 01/01/05 to 12/31/05
Outputs
On-the-go remote sensing resulted in strong relationships between the green normalized vegetation index (GNDVI) and leaf N beginning at early flowering. A biomass N index calculated by multiplying GNDVI X Leaf N, resulted in regression coefficients of 0.92 and greater from early flowering through early senescence. Addition of the urease inhibitor NBPT to broadcast urea resulted in an increase in fertilizer N recovery by no-till cotton of 17.6% when compared to untreated urea and 6.4% for treated liquid urea ammonium nitrate (UAN) compared to untreated UAN. Treated urea performed most similarly to broadcast ammonium nitrate.
Impacts
Spatial application of fertilizer N guided with on-the-go sensing could help reduce variability in cotton growth across fields with intangible benefits in reduced need for growth regulators and crop desiccants. Improved N-use efficiency from urease inhibitor treated urea will partially offset rising fertilizer N costs, provide a more acceptable substitute for ammonium nitrate, and reduce ammonia emissions to the atmosphere from this N source.
Publications
- Adeli, A., J.J. Varco, K.R. Sistani, and D.E. Rowe. 2005. Effects of swine lagoon effluent relative to commercial fertilizer applications on warm-season forage nutritive value. Agron. J. 97:408-417.
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Progress 01/01/04 to 12/30/04
Outputs
A field study has been initiated to develop cotton growth and nutritional monitoring techniques utilizing on-the-go remote sensing. Preliminary research has demonstrated the feasibility of this technique for these purposes. In an effort to improve N-use efficiency in no-till cotton, a urease inhibitor will be evaluated for its effectiveness in reducing volatile ammonia emissions from urea applied fertilizer.
Impacts
Development of on-the-go sensing techniques will be a great economic benefit in the management of agrichemicals in cotton production on highly variable alluvial soils. Spatial application of fertilizer N could help reduce variability in cotton growth across fields with intangible benefits in reduced need for growth regulators and crop dessicants. An improvement in N-use efficiency could help to offset rising fertilizer N costs.
Publications
- No publications reported this period
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