250 N uptake N removed. N rate, lb/ac

Transcription

1 Costs and Benefits of Different N Sources for Cotton Louisiana Agricultural Technology and Management Conference Alexandria, LA February 11-13, 13, 29 Donald Boquet LSU AgCenter

2 How much nitrogen does a cotton crop need for optimal growth and yield? How much fertilizer nitrogen does a cotton crop need for optimal growth and yield??

3 25 N uptake N removed N rate, lb/ac Total per acre nitrogen uptake and removal by cotton on Commerce sl, 2-yr average. (No residual N.)

4 25 N uptake N removed N rate, lb/ac Total per acre nitrogen uptake and removal by cotton on Commerce silt loam, 2-yr average. (With residual nitrogen)

5 25 N uptake N removed N rate, lb/ac Total per acre nitrogen uptake and removal by cotton on Commerce sl, 2-yr average.

6 1 N uptake 8 93 N removed N rate, lb/ac 37 Nitrogen uptake and removal per bale of cotton on Commerce sl, 2-yr average.

7 Sources of Nitrogen Free Fertilizer N

8 Free Sources of Nitrogen Native soil N (Organic matter, Clay-fixed, N fixation by algae) Residual N ( From fertilizer N applied in last 3 years) Vegetation mineralization Added N from all other sources

9 Not free sources Fertilizer N 2/9/9 Ammonium nitrate 67 to 92 cents/lb UAN cents/lb UAN 3 + S 61 to 71 cents/lb Urea to 46 cents/lb Anhydrous 2 cents/lb Legume N 4 to 6 cents/lb

10 Fertilizer N Costs Cost of fertilizer N per acre* $36 to $57 Cost of Fertilizer N as percentage of total input costs -- 6 to 1% Cost of Fertilizer N per pound of lint $.36 to $.57 * silt loam soils

11 Strategies to minimize fertilizer N costs? Applying split applications of soil- applied or foliar-applied applied N? Using in-season monitoring of crop N status -- sensing of leaf/crop greenness? Using site specific applications based on field variability?

12 Strategies to minimize fertilizer N costs? Delaying fertilizer application to wait for price to decrease? Use the minimal rates needed based on research and experience.

13 For most alluvial and loess silt loam soils, a For most alluvial and loess silt loam soils, a fertilizer N rate of 75-8 lb/a is optimum for yield and management of cotton.

14 y = x x 13x + 72 R 2 = Fertilizer N rate, lb/a Dryland cotton response to cover crop and N rate on Commerce silt loam, 7-yr. avg.

15 y = -86x x R 2 = Fertilizer N rate, lb/a Dryland cotton response to cover crop and N rate on Sharkey clay, 2-year avg.

16 Lint yield, lb b/acre 16 R 2 = NH4NO3 14 Urea 12 =85 2 Nitamin 43 = R 2.85 R Nitrogen rate, lb/acre Cotton yield response to three formulations and six rates of N fertilizer on Gigger silt loam,

17 Lint yield, lb b/acre R 2 =.87 R 2 =.88 UAN Nitamin 3L Nitrogen rate, lb/acre Cotton yield response to two formulations and six rates of N fertilizer on Commerce silty clay loam, 27 and 28.

18 Le eaf N conc c, % R 2 = June 1 Aug R 2 =.95 R 2 =.95 R 2 =.91 R 2 =.92 R 2 =.54 NH4NO3 Urea Nitamin Nitrogen rate, lb/acre Cotton leaf N response at flower initiation and boll fill to fertilizer N forms and rates on Gigger silt loam, 26.

19 lb/a Lin nt yield, Commerce sl Gigger sl y = x x R 2 =86.86 y = x x R 2 = Cotton fertilizer N rate, lb/ac Response of cotton yield following corn to fertilizer N rate on Gigger sl and Commerce sl, 4-yr avg.

20 Split Nitrogen Applications Soil-applied Foliar-applied applied

21 ld, Seedcot tton yie lb/ acre at bloom initiation 25 at mid-bloom Response of cotton yield to single N applications at different times on Commerce silt loam.

22 Lint yield, lb b/acre LSD(.5)=13 1% at planting 2/3 + 1/ Total N rate applied, lb/ac Response of cotton yield to single and split N applications of 5, 75, and 1 lb on Commerce sl. 4-yr avg. Second appl. at flower initiation.

23 16 LSD(.5)= NH4NO3 Urea Nitamin 43 Response of cotton lint yield to single and split 125 applications of NH4NO3, Urea and Nitamin formulations on Gigger sl,

24 Lint Yie eld, lb/a acre 16 LSD(.5)= At Planting 12 Split appl NH4NO3, 125 NH4NO3, 75 Response of cotton lint yield to single and split 75 and 125 lb NH4NO3 applications on Gigger sl, 26.

25 lb/acre See edcotton yield, LSD(.5)= at planting at planting Response of cotton yield to single and split applications of 9 lb/ac N as UAN on Commerce silty clay loam, 28. Second application at flower initiation.

26 14 LSD(.5)= at planting UAN 32 Nitamin 43 Response of cotton lint yield to single and split 75 lb N applications or UAN and Nitamin 43 on Commerce silty clay loam,

27 LSD(.5)=149 1 at planting UAN 32 Nitamin 3L Response of cotton lint yield to single and split 1 lb N applications on Commerce silty clay loam,

28 16 LSD(.5)= at planting UAN 32 Nitamin 3L Response of cotton lint yield to single and split 125 lb N applications on Commerce silty clay loam, 27.

29 14 LSD(.5)=11 check 12 Urea 1 Nitamin 3L Coron soil-applied 6 soil-applied Response of cotton lint yield to soil- and foliar-applied applied N,

30 Summary for Fertilizer N N formulation has little or no effect on cotton lint yield response. The optimal N rate for soil-applied N is 75 lb/acre on the silt loam soils and 9 to 1 lb/acre on the silty clays and clays. Cost of fertilizer N varies with form - 45 to 71 cents per pound.

31 Summary for Fertilizer N Foliar-applied applied N effects are small and inconsistent pointed out yesterday by Dr. Phillips. Split N applications are seldom economic, whether soil or foliar applied. The majority of the N used by a cotton crop is free.

32 Legume Nitrogen Crimson clover in Missouri in early May Self reseeding crimson clover In Missouri in October Hairy vetch in early April in Louisiana Crimson clover in Alabama in early Mar

33 Vetch Native Fertilizer N rate, lb/ac Irrigated cotton response to N rate following different cover crops on Gigger sl, 5-yr avg.

34 Winter legume cover crop supplies 5% of N requirements on Sharkey clay.

35 Legume crops for N Vetches (hairy, common, big flower) Winter peas (Austrian, Caly, Roughpea, Singletary) Clovers - Crimson, Berseem, Arrowleaf, Bur, Sub, Red, White, many others) Medics Barrel medic, annual lucerne Lupines White, blue and yellow

36 Why plant legume crops for N? Relative cost of other N sources Inorganic fertilizers Organic (poultry litter, gin trash, composts) Soil organic matter increase Soil quality improvement Winter ground cover for BMPs Intangibles (improved soil tilth & biology

37 Why not plant legume crops for N? Relative cost of other N sources Uncertainty of production Time management fall planting; possible delay with spring planting preparation and planting itself. The unknowns Depletion of soil water; increase nematode numbers? diseases?; termination timing and cost.

38 lb N/acre Cotton yield following legume crops, LSU AgCenter Northeast Research Station, 22 years, No cover or N 2 Hairy vetch Common vetch 15 Hungarian vetch Smooth vetch 1 Crimson clv. A. winter pea 5 Caly ypea 24 lb N/ac Data from C.B. Haddon from 36 species evaluated

39 Above ground biomass yield and N content of legume cover crops in LA, 5 yr. avg., Biomass N content ---- lb/ ac ---- Hairy vetch Crimson clv. (Chief) Austrian winter pea Roughpea (Caley) Berseem clv Bur clv. Serena Lupin Tifblue Data from Seth Dabney, formerly LSU AgCenter, now USDA

40 Lb N/acre Nitrogen content of legume crops with time of harvest in Louisiana. 16 Ci Crimson Berseem Arrowleaf Sub 1 BF vetch Mar 1 Apr 1May 22 May Harvest or termination date

41 Summary for Legume N Winter legumes biomass contain from 1 to 15 lb N/acre in early spring. Up to 8 % of this N can be available for the following summer crop. Based on past research, the best overall legume is hairy vetch followed by several of the clover species and by winter peas. Cotton planted in hairy vetch residue Cotton planted in Austrian winter pea residue

42 Summary for Legume N Legumes should be chosen for early growth, total N and tolerance to cold. The largest impediment to effective use of winter cover crops for N is the conflict with maximum N fixation time (early spring) and planting of the following summer crop. Cotton planted in hairy vetch residue Cotton planted in Austrian winter pea residue

43 Thank You Questions?