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Fluid Journal : Fluid Journal 2002-2004
Spring 2004 Phosphorus Fertilizer Bumps Forage and Beef Production Drs. D. Robinson, J. Sij, W. Pinchak, R. Gill, D. Malinowski, T. Baughman and Mr. S. Bevers Summary: Four annual applications of 40 lbs/A of P2O5 raised surface soil test Plevelsfrom9or10ppmto23ppm, but did not significantly increase grain yields. Forage production increased by 35 percent, although more dramatically prior to March 1. Beef production increased by 32 percent in the graze-plus-grain system and by 34 percent in the graze-out system. There was no advantage to deep placing fertilizers. Economic returns to land and management in the graze-plus- grain system averaged $42 and $34/A with surface-applied and injected nitrogen (N), phosphorus (P), sulfur (S) fertilizer, respectively, and $30/A with NS fertilizer. The graze-out system was consistently less profitable, returning only $13 and $3/A with surface-applied and injected NPS, respectively, and $5/A with no P in the fertilizers. Although both forage and beef production were increased by one-third and increased income sufficiently to exceed the cost of added P, the profit margin was very narrow in the graze-plus grain system and negative in the graze-out system. The study confirms our belief that grain production is still extremely important in Rolling Plains wheat-stocker cattle production programs. Forage and Beef production increased sufficiently to exceed the cost of added P. Fluid Journal 1 N Table 1. Mean forage production in grazed pastures of 'Lockett' wheat receiving three soil fertility practices in two management programs during three years at Vernon,Texas. Fertilizer Forage* production through February Applied 2000 2002 2003 Mean --------------- --- ---lbs/A--------------------- --- N surface 1,420 1,190 835 1,150 NP surface 1,650 1,910 1,785 1,780 (55%) NP deep 2,095 1,450 1,795 1,780 Forage* production from March through May N surface 2,860 2,640 3,015 2,840 NP surface 3,360 3,155 4,220 3,580 (26%) NP deep 2,825 2,995 3,565 3,125 * Forage yields were estimated as the difference between forage weights in caged and uncaged areas taken one month apart. Table 2. Beef and grain production from 'Lockett' wheat grown with three soil fertility practices for three years in a graze-plus-grain management system at Vernon, Texas. Beef gain per acre Fertilizer Head/day Head 1999- 2001- 2002- Grain yield Applied mean* mean 2000 2002 2003 2003 mean ---------------------pounds--- --- ------------------ ---bu/acre--- N surface 2.2 16185706232 26 NP surface 2.3 170 102 103 81 38 28 NP deep 2.4 175108789041 31 * Means from three years of data. early 20 million acres of hard red winter wheat are grown in the semiarid Southern Great Plains. The use of winter wheat as a dual-use crop is an extremely important component of the agricultural econo- mies of Texas, southern Kansas, eastern New Mexico, western Oklahoma, and southeastern Colorado. The grazing value of winter wheat forage has been known since the 1930s. Depending on cattle and grain prices, farmers and ranchers have the option of either grazing out wheat if cattle prices are high relative to wheat grain, or removing cattle and allowing the wheat to develop grain if wheat prices are high relative to cattle. Recent estimates indicate that 30 to 80 percent of the wheat planted is grazed to some degree. Dual-use wheat production is more complex and requires a higher level of management than permanent pastures, wheat for pastures only, or grain only. Fertilizers, particularly N and P, are essential in maximizing forage and grain production in nutrient-deficient soils. A deficiency in either N or P can result in significantly reduced forage and grain yields. Unfortunately, there is
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