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Interpretive Summaries:
2004 - Wheat Pasture Response to Maintenance Phosphorus and Nitrogen Fertilizer in Dual-Use, Wheat/Stocker Systems on the Texas Rolling Plains
2003 - Grain and Grazing Responses to Phosphorus Placement in Wheat Pasture in the Texas Rolling Plains
2002 - Grain and Grazing Responses to Phosphorus Placement in Wheat Pasture in the Texas Rolling Plains
2001 - Grain and Grazing Responses to Phosphorus Placement in Wheat Pasture in the Texas Rolling Plains
2000 - Grain and Grazing Responses to Phosphorus Placement in Wheat Pasture in the Texas Rolling Plains
1999 - Grain and Grazing Responses to P Placement in Wheat Pasture in the Texas Rolling Plains
Wheat Pasture Response to Maintenance Phosphorus and Nitrogen Fertilizer in Dual-Use, Wheat/Stocker Systems on the Texas Rolling Plains, 2004
Winter wheat is used for both grain and forage in the Southern Great Plains. A recently completed 4-year study at the Texas Agricultural Experiment Station at Vernon showed that phosphorus (P) fertilizer significantly increased wheat forage yield and stocker cattle gains. During the 4 years of this work, 160 lb P2O5/A was applied to pastures that received P fertilizer. This resulted in a two- to three-fold increase in soil P levels. The current experiment utilized the treatments from the previous study to evaluate the impact of residual P on wheat forage and grain production. Specific objectives were to: 1) determine the influence of residual P on forage, beef, and grain yields in dual-use, wheat/stocker production systems, and 2) evaluate the effect of maintenance P application on forage, beef, and grain production.
Nine 25-acre pastures were used in this experiment. The three treatments included: 1) nitrogen (N) only (65 lb N/A) applied to the previous study’s zero P control pastures (low soil P level), 2) N only (65 lb/A) applied to pastures that received P during the previous study (high soil P level), and 3) N (65 lb N/A) plus maintenance P (20 lb P2O5/A) applied to pastures that received P during the previous study (high soil P level). All treatments were surface-applied and incorporated. One of the three replications was abandoned due to drought, poor stands, and severe depredation by deer. Stocker cattle were placed on December 11, 2003. The number of head per pasture was determined based on a given forage allowance per hundredweight of beef. Stocking rates were adjusted every 28 days based on forage allowance in each pasture.
The fall and winter months were extremely dry, hence there was limited forage production until February. Residual P increased total, season-long forage production by about 2,400 lb/A. Although this response was not statistically significant, it is nevertheless noteworthy. Treatment effects on cattle gains in the grain/grazing system were not significant, probably because of the dry conditions during grazing. However, in the graze-out system residual P had a significant impact on beef production… increasing gain per acre by about 67%. The maintenance P application did not increase forage yield above the residual P treatments. There was no significant difference in grain yield among treatments. This study has helped demonstrate that the value of P fertilization extends well beyond the year of application. This is the final year of this work. TX-44F
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