TITLE:

 

Nitrogen Fertilizer for Peanut at AG-CARES, Lamesa, TX, 2002, and Summary of Four South Plains On-Farm N Rate Trials for Peanut

 

AUTHOR:

 

Calvin Trostle, Texas Cooperative Extension--Lubbock; Danny Carmichael, TAES-Lubbock,

c-trostle@tamu.edu, (806) 746-6101

           

METHODS AND PROCEDURES (for guar planting):

 

Soil Type:                Amarillo fine sandy loam

Planting:                  May 2, 2002

Previous Crop:        Cotton

Seed & Rate:          Flavor Runner 458 peanut, ~5.5 seeds/ft. on 40-inch rows

Inoculant:                Urbana RhizoFlow granular, ~5.5 lbs./A (1X rate)

Plot Set-up:             Four replicated plots per each N rate, test area per variety 4 rows X 60’

Harvest Area:         4 rows X 60’

Fertilizer:                 0, 50, and 100 lbs. N/A applied by hand broadcast as urea, June 28, 2002, and watered in within 2 hours

Rainfall:                  See summary in AGCARES report, 3.71” from June 28-Oct. 10 (period of physiological growth)

Soil test N:              Surface soil test N was medium; with subsoil N, tests reported ~65 lbs. available N/A in the top 3’.

Date Harvested:      October 17, 2002

 

RESULTS AND DISCUSSION:

 

Past research on nitrogen fertilizer and peanut yield response at AGCARES has shown no benefit from N fertilizer additions.  Unfortunately, much of that work was conducted on ground that had as much as 175 lbs. N/A in the top three feet of soil.  Nor was any record of nodulation on peanut recorded.  Subsoil N was lower in this trial, although perhaps still enough to cloud possible yield response to N fertilizer.  We are disappointed with the result of the nodulation in this trial.  In general, 2003 was a “nodulation year” for peanut across the South Plains, with many fields averaging 40 to nearly 100 nodules per plant.  No response to N was observed in this trial, which will be repeated on-farm in Dawson Co. in 2003.

 

Table 1.  Nodulation, nodule size, and yield response to three mid-season broadcast N treatments at AGCARES, Dawson Co., TX, 2002.

AGCARES

Nodule count

Avg. nodule

Yield

Grade

N Rate

per plant^

Diameter (in.)^

(Lbs./A)^

(%SMK+SS)^

0

9.3 a

0.124 a

3616 a

Not

50

9.7 a

0.124 a

3641 a

yet

100

11.1 a

0.124 a

3655 a

determined

Mean

10.0

0.123

3637

 

P-Value

0.7958

0.7823

0.8776

 

Fisher's PLSD (0.05)

NS#

NS

NS

 

Coeff. of Variation (%)

36.3

5.2

2.8

 

^Means in the same column followed by the same letter are not significantly different at 0.05.

#Not significant.

 

 

 

 

In addition, six identical on-farm nitrogen trials for peanut were conducted across the Texas South Plains in 2003.  In only one case was any response to nitrogen fertilizer observed, and that was on an uninoculated crop in Gaines Co.  For the most part Rhizobium nodulation was good to excellent, and soil N levels did not explain why yield response to N would not have occurred (i.e., soil N levels were not unduly high).  In contrast, on-farm tests in 2001 indicated significant yield response to mid-season N fertilizer at 50 lbs. N/A, but not always at 100 lbs. N/A.  In general, nodulation was not nearly as good in 2001.

 

Research at the Western Peanut Growers Assn. Research Farm, Gaines Co., did indicate strong response to both inoculant and mid-season N applications.  These results occurred where peak yields exceeded 6,500 lbs./A.  In general, however, yield increases were slightly higher in response to the best liquid peanut Rhizobium inoculant products.  Results suggest that farmers’ expenditure for good inoculant and its proper application is more valuable than N fertilizer expense.

 

Table 2.  Summary of six identical Texas South Plains on-farm mid-season N fertilizer trials (0, 50, and 100 lbs. N/A) for peanut (for a complete report, contact Calvin Trostle).

On-Farm County

Rhizobium

General Yields

Yield Response

Relative

Location

Inoculation Rate

(Lbs./A)

to N Fertilizer?

Nodulation

Gaines CR

0X

5500

Yes

Good

Gaines CR

1X

6150

No

Excellent

Gaines CR

2X

6150

No

Excellent

Yoakum 1

1X

3300

No

Fairly Good

Yoakum 2 (caliche)

1X

3900

Trend

Good

Terry

1X

5800

No

Very good

 

Peanut and Rhizobium Inoculation Resources:  For a full report of 2002 South Plains nitrogen and inoculation research, contact Calvin Trostle.  Do you have questions about peanut inoculant products and how to improve your chances for good nodulation of peanut?  Are you sure you are getting the nodulation you should on your peanuts?  Refer to the above report for product information.  For tips on improving Rhizobium inoculant use and avoiding common mistakes of just nuisances in peanut inoculation, consult “Questions and Answers about Peanut Inoculation in West Texas,” through your county Extension office, Calvin Trostle, or the Texas A&M—Lubbock website at http://lubbock.tamu.edu