Cooperators: Buzz Steele, producer, Brownfield & Calvin Trostle, TAEX- Lubbock.
Crop Information and Observations:
Soil type: Brownfield sandy loam (?)
1998 - Planted first to cotton (failed), then sorghum (never emerged);
pre-plant fertilizer was ~50 units of 11-52-0 then 100 lb. of KMag; received
~90 lb. of 10-34-0 when listed up.
1999-Planted to Kenmin variety 4 lb. per acre on ~June 17,1999, after failed cotton (hail) Harvested December
2, 1999 (JD 9500 with flex header).
Seedbox Nitrogen Rhizobium inoculant for guar was mixed with unwetted seed; nodules were hard to find with average
of about 0.5 per plant.
Early-season fertilizer for cotton: listed 120 lb./A of 10-34-0 below the bed.
Mid-season N applications were knifed in at ~10" deep about 10" to side of row. Tractor operator observed that soil was very
dry when "late" N was applied.
Soil profile moisture at planting was excellent; received about 4" of total in-season rainfall (~2" near Aug. 20, and
Ӯ" in September).
Three strips, each approximately 0.9 A in area were harvested for each treatment.
Crop probably received first frost about October 19th.
| N Treatment | Date Applied | Actual N Rate | Average Yield | Statistical Significance |
| lb. per Acre | ||||
| Control | -- | None | 898 | A |
| "Early" Low | 7/26/99 | 27 | 1042 | A |
| "Early" High | 7/26/99 | 44 | 1038 | A |
| "Late" Low | 8/4/99 | 22 | 979 | A |
| "Late" High | 8/4/99 | 45 | 1013 | A |
| F=2.162, P=0.1472 | ||||
| *Treatments followed by the same letter are not statistically significantly different at Alpha = 0.10 (i.e., P < 0.10, the level of certainty). Thus numerically, if treatments were declared significantly different, then there would have been at least a 90% chance that the differences in the treatment yields were due to the treatments and not some other factor. | ||||
The trend in the dryland guar suggests that some response was achieved to the N fertilizer applications although the statistical analysis suggests that the variability within the treatments was sufficient to render the differences nonsignificant. Little or no nodulation of the guar suggests that these plants may received little N from Rhizobium fixation making the crop more likely to respond to limited N. Keep in mind that any application of the results in future cropping should be restricted to the specific conditions which were tested in 1999. Based on the results under the conditions of this test, it appears that the cost of the mid-season N application was recovered in terms of slightly higher yields Further testing of guar yield response to N is needed to develop recommendations for guar in the Texas South Plains.
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Cooperators: Buzz Steele, producer, Brownfield & Calvin Trostle, TAEX- Lubbock
Crop Information and Observations:
Soil type: Brownfield sandy loam (?)
1998-Planted first to cotton (failed) then to sorghum (never emerged) pre-plant fertilizer
broke in was approximately 65 units of P2O5 and 40 units of K2O; received ~90
lb. of 10-34-0 when listed up.
1999-Planted to Kenmin variety 4 lb./A on ~June
24, 1999, after failed cotton (hail) Harvested December 2, 1999 (JD 9500 with
flex header)
Seedbox Nitrogen Rhizobium inoculant for guar was mixed with unwetted
seed; nodules ranged from 0 to 6 per plant with an average of about 2.0 per
plant.
Early-season fertilizer for cotton: listed 120 lb./A of 10-34-0 below
the bed.
Soil profile moisture at planting was excellent; received two 1 in. irrigations
in addition to about 4 in. of total in-season rainfall (~2in. near Aug. 20, and ~2 in.
in September).
Four strips, each approximately ranging from 0.8 to 0.9 A in area
were harvested for each treatment.
Crop probably received first frost about October 19th,
| N Treatment | Date Applied | Actual N Rate | Average Yield | Statistical Significance |
| lb. per Acre | ||||
| Control | -- | None | 1297 | A |
| "Early" Low | 7/29/99 | 59 | 1298 | A |
| "Early" High | 7/29/99 | 104 | 1277 | A |
| "Late" Low | 8/9/99 | 54 | 1238 | A |
| "Late" High | 8/9/99 | 88 | 1272 | A |
| F=0.98, P=0.4484 | ||||
| *Treatments followed by the same letter are not statistically significantly different at Alpha = 0.10 (i.e., P < 0.10, the level of certainty). Thus numerically, if treatments were declared significantly different, then there would have been at least a 90% chance that the differences in the treatment yields were due to the treatments and not some other factor. | ||||
The results of the irrigated guar suggests that no response was achieved to the N fertilizer applications. In terms of field variability this field was very uniform. Among 10-12 guar fields observed in 1999 for Rhizobium nodulation, this field had more nodulation than other fields. Based on the results under the conditions of this test, the cost of the mid-season N application was not recovered. It is possible that a higher level of soil fertility on this field could have reduced any possible response to N. Further testing of guar yield response to N is needed to develop recommendations for guar in the Texas South Plains.
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