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Fluid Journal : Fluid Journal 2005-2007
Returns Mixed On Wheat Pasture Response To N and Maintenance P in Wheat/Stocker Systems J. Sij, W. Pinchak, J. Ott, B. Min, D. Malinowski, D. Robinson Even though yields were increased nearly 6 bu/A, a rough analysis shows returns were only marginally profitable. Proper fertilizer management in small grain production is key to profitability, since cost of material and application are major economic inputs. Phosphorus (P) and nitrogen (N) fertilizers are key inputs to successful wheat production. Considerably less research has been conducted in dual-use, wheat/stocker operations. Introducing an animal component increases the complexity of fertilizer management in order to maximize forage, grain yield/quality, and beef yields. Phosphorus. Recently completed studies by the Texas Agricultural Experiment Station at Vernon have shown that P fertilizer increased early forage yields 55 percent from planting to March 1 and 35 percent over the entire grazing season. Beef gains per acre were increased 34 percent during the entire season, since pastures fertilized with P could support higher stocking rates due to increased forage production. Surface-applied P was as good as deep-placed P in increasing forage yields and subsequent beef production. Nitrogen. Another key input to all wheat production is N fertilizer, but information on N fertility response of wheat in a no-till grazing system does not exist. Since N is an expensive input in wheat production, a study was initiated in 2003 to evaluate and compare N fertilizer requirements in a no-till, wheat/stocker production system with that from a conventional- till wheat/stocker system. Objectives of this dual-use wheat/ stocker production system study were to 1) determine the effects of N fertility management on forage, forage protein, grain yield, and grain quality in no-till and conventional-till systems, 2) determine the influence of residual P on forage, beef, and grain yields, and 3) evaluate the effect of 20 lbs/A of P2O5 as a "maintenance" P application on forage, beef, and grain production. Results were compared with pastures receiving N only. Spring 2006 FLUID JOURNAL Page 1 Application of a maintenance level of phosphorus (P) to a soil high in P and previously used for a successful wheat grazing study did not positively impact production levels in a dual-use, wheat/stocker production system. Forage yields to December 15, 2003 did not differ among treatments and averaged only 189 lbs/A of dry matter due to severe moisture stress. No significant differences in forage production were observed during the grazing period under these conditions. Nitrogen (N) fertilization over 60 lbs/A did not significantly increase forage yields by April 22 (heading date). Grain yields increased with increasing N rates, and topdressed N further increased grain yields on an average of approximately 6 bu/A, except at the highest preplant N rate of 120 lbs/A. With only a 6 bu/A grain yield increase and limited grazing, a rough economic analysis showed that returns were only marginally profitable. Across all treatments, the conventional-till treatment out yielded no-till by 10 percent or 3.5 bu/A, possibly due to less soil compaction under the conventional-till system. Abnormally dry conditions prevailed from planting through mid-winter. Figure 1. Forage production from Lockett wheat with and without maintenance P, 2003-04.
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