GRAZING AND GRAIN RESPONSES TO PHOSPHORUS AND PHOSPHORUS PLACEMENT by ckd11816

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									    GRAZING AND GRAIN RESPONSES TO PHOSPHORUS AND PHOSPHORUS
            PLACEMENT APPLIED TO WHEAT PASTURE IN TEXAS
                               Texas Agricultural Experiment Station
                                          Vernon, Texas

    Don Robinson, Bill Pinchak, John Sij, Ron Gill, Todd Baughman, and Stan Bevers1
      dl-robinson@tamu.edu; w-pinchak@tamu.edu; j-sij@tamu.edu; r-gill1@tamu.edu;
                       ta-baughman@tamu.edu; s-bevers@tamu.edu

                               ANNUAL REPORT - FEBRUARY 2003


   The current report contains results from the first and third years of forage production and
animal performance in the Texas Rolling Plains during three years. No forage was available for
grazing during the second year of the study (2000-2001). These results will be combined with
future results to validate their accuracy and hopefully form credible conclusions based on three
years of grain production and animal performance.

                                            JUSTIFICATION

    Wheat (Triticum aestivum L. em. Thell.) is used for both grain and high quality forage in the
Southern Great Plains. There are over 6 million acres of wheat planted in Texas each year, and
approximately 65% of the crop is harvested for grain (Texas Agricultural Statistics, 1998).
Nearly 70% of the Rolling Plains wheat crop (over 1.2 million acres) is grazed each year (Miller,
1998). The economic impact that includes grain, grazing, and grazing/grain systems for the
Rolling Plains region of Texas is significant. Since the 1940's, there has been considerable
interest among farmers and ranchers to utilize wheat as a dual purpose crop (Schlehuber and
Tucker, 1967). In this system, wheat is grazed during the winter and cattle removed in early
spring to produce a grain crop. Depending on cattle and grain prices, farmers and ranchers
have the option to either graze out wheat if cattle prices are high relative to wheat or remove
cattle and allow the wheat to develop grain if wheat prices are high relative to cattle. A third
alternative would be to make hay or silage from the wheat crop and use the forage as
supplemental feed later in the year. Weather and lease arrangements also enter into decisions
concerning grain/grazing options. The versatility of wheat in this region is obvious and provides
farmers and ranchers income options not found in other major hard red winter wheat production
areas of the U.S. The use of winter wheat as a dual-purpose forage and grain crop is important
to the agricultural economies of Texas, southern Kansas, eastern New Mexico, western
Oklahoma, and southeastern Colorado. (Pinchak et al., 1996; Ralphs et al., 1997; Redmon et
al., 1995; Shroyer et al., 1993).

                                             BACKGROUND

   Earlier studies indicated that deep placement of phosphorus (P) significantly increased
forage and grain yields in dual purpose wheat production programs (Miller, 1998). Increases in
wheat grain yields from deep placement of P have not always occurred but are most often

1
 Todd Baughman, Stan Bevers, Bill Pinchak, Don Robinson, John Sij, Texas A&M Research & Extension Center,
P.O. Box 1658, Vernon, TX 76385, Phone: 940-552-9941, FAX 940-553-4657; Ron Gill, Texas A&M Research &
Extension Center, 17360 Coit Road, Dallas, TX 75252, Phone: 972-952-9233, FAX 972-952-9227.




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associated with dry conditions throughout the growing season. Given the probability of dry
growing conditions in the Rolling Plains region of Texas, deep placement of P can be a positive
input and help alleviate some of the problems associated with dry years.

   Data averaged from eight test locations from 1988 to 1992, showed that deep-placed P and
N resulted in 730 lbs/acre more forage than did N alone. Wheat yields from six locations during
this period averaged approximately 10 bu/acre more grain where P plus N was placed deep
compared with N alone. Nearly 70% of the Rolling Plains wheat crop is grazed, with 40 to 45%
of the crop grazed the entire season (Miller, 1998). Assuming a 16 to 1 forage to gain
conversion ratio, a 730 lb/acre increase in forage could provide 48 lbs/acre additional beef gain.
At $0.35/lb (lease rate), the gross return amounts to $17.00/acre. Similarly, a 10 bu/acre
increase at $3.00/bu amounts to $30.00/acre increase from grain yield, for a total return of
$47.00/acre (gain plus grain). Considering that 1.3 million acres of wheat are planted annually
in the Rolling Plains, increased returns through efficient and proper application of P and N
fertilizers could readily exceed $15 million dollars.

                                          OBJECTIVES

      1.   Determine the influence of P fertilizer and P fertilizer placement on forage, beef, and
           grain production from dual-purpose wheat.
      2.   Evaluate grazing termination date effects on grain yield and animal performance.
      3.   Identify economic costs and returns associated with P fertilizer and P placement
           methods and length of grazing period of winter wheat in the Texas Rolling Plains.

                                 METHODS AND MATERIALS

    The test site is located in Wilbarger County, approximately eight miles south of Vernon,
Texas, and east of Highway 183/283, on a Tillman clay loam series. The experiment included
three replications of three fertility treatments: 1) surface-applied N and S, 2) surface-applied N,
S, and P, and 3) deep-placed (6 to 8 inches) N, S, and P. Soils were sampled at 0 to 2 and 2 to
6 inches deep in August each year prior to wheat planting to characterize fertility levels. The
test location was initially deficient in N and P and a response to applied P was anticipated. All
fertilizers were applied as liquids in late August to early September each year using commercial
applicators. Each of the nine pastures or plots was 25 acres. Shortly after fertilizer application,
all plots were field cultivated to control weeds, incorporate fertilizer, and prepare the seedbed.
>Lockett= dual-purpose wheat was seeded at a rate of 75 lbs/acre in late September. In early
December, forage biomass was measured and each pasture was stocked with 500-lb beef
animals at a uniform forage-to-animal weight ratio. By the end of the season, a total of 190 to
200 head was utilized on 225 acres.

    Cattle were individually ear-tagged, weighed, and assigned to nine uniform groups, one for
each 25-acre pasture. Cattle were weighed at approximately 28-day intervals throughout the
study. Forage production, forage utilization, and animal gain were measured monthly to
quantify forage relationships to animal gain. Estimates of forage standing crop, growth, and
utilization were made from five paired caged and uncaged plots (15.6 ft2 each) in each pasture.
Forage was hand-clipped. The five cages were randomly repositioned after each forage
clipping. Two additional cages in each pasture were never moved and sampled shortly after the
cattle were removed in May to determine the biomass of non-grazed wheat. Grazing pressure
in each pasture was adjusted occasionally to maintain comparable forage allowance per animal
live weight, causing animal numbers to vary among pastures. Forage utilization was estimated
as differences in caged and uncaged standing crop at each date cattle were weighed. Grazing


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continued from early December through early May. At first hollow stem, (about March 1), two
cages (8x16 feet) were installed in each pasture so that two management systems, graze-plus-
grain and graze-out, could be compared for production and economic returns. At maturity, plots
within cages were end-trimmed and grain yield was determined by machine harvesting the
center section of each plot. Yields were adjusted to 13% moisture and 60 lbs/bu. Statistical
analysis utilized a repeated measures analysis of variance orthogonal contrast. An economic
analysis was conducted to assess the profitability of P and P placement in dual-purpose wheat
on the Texas Rolling Plains and to compare grazing-plus-grain with grazing-only systems.

                                  RESULTS AND DISCUSSION

    The data in Table 1 show cumulative forage production during the grazing seasons as
influenced by the three soil fertility practices during two years of the study. It is apparent that P
applications, regardless of application method, consistently increased forage yields, and the
response was greater the second year than the first year. During the early grazing phase of
December through February, P applications increased forage production by about 200
pounds/acre (lb/A) the first year and by as much as 800 lb/A the second year. By the end of the
grazing season in May, forage yields had increased by an average of 675 and 1040 lb/A in the
two years due to P applications.

   Other studies indicated that wheat forage production responses to P applications were
greatest in dry years and least in wet years. We observed a similar situation, with forage
responses being most apparent in the fall when soils were dry and disappearing as late winter
to early spring rains occurred. However, the yield data show that P effects on forage production
are season-long even though differences in the spring are not visually apparent. We observed
no advantage to deep placement of P in this study, although the location of knife rows could be
identified by the larger, dark-green wheat plants in late fall.

   Data in Table 2 show beef and grain production in the graze-plus-grain management system
during two years as influenced by P and P placement. Because we attempted to keep constant
forage availability per unit of animal live weight in all pastures, the gain per head per day (ADG)
and gain per head would be expected to be the same in all pastures. Greater forage production
within any pasture should be reflected in greater animal gains per acre as a result of heavier
stocking rates that pastures could support. The data indicate that all measures of animal gain
were increased by P applications the first year of the study during the early grazing phase.
Keep in mind that differences in forage production among pastures averaged only about 200
lb/A during this grazing phase. Perhaps the reason for the unexpected result is that the
aggressive stocking rate lowered individual animal performance in pastures with less forage.
Gain per acre was increased nearly 22% in pastures receiving P fertilizers. During the second
year, ADG and gain per head were similar regardless of soil fertility treatment, but gain per acre
was again increased by approximately 30% where P was applied. Stocking rates were higher
the first year than the second year, reflecting the greater early forage production the first year.

   Grain yields were not influenced by P applications for crops harvested in 2000 or 2001.
(Recall that no forage was available for grazing and only grain was produced in 2001). In 2002,
grain yields were increased 5 to 8 bushels per acre where P was applied.




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   Animal performance and ungrazed forage production data under the graze-out program are
presented in Table 3. Animal gain/head/day and gain per head were similar regardless of soil
fertility practice. However, gain per acre was increased both years where P was applied: 39%
the first year and 21% the second year the study was grazed. The resulting stocking rates were
similar between years on a season-long basis, reflecting similarities in total forage production.
Also, the higher forage production levels in the presence of P applications are indicated by
higher stocking rates. Season-long ungrazed forage yields were increased by P applications.
In all cases, surface applied P was as good or better than deep-placed P.

   An economic analysis was conducted by creating an enterprise budget for each fertility
treatment. Table 4 contains a summary of income, expenses, and profit or loss from each
fertility practice in both the graze-plus-grain and graze-out systems. Total income was
consistently higher where P was applied, regardless of the management system. Increases in
income were greater in the graze-plus-grain system than in the graze-out system because of the
positive grain yield response. The graze-plus-grain system returned more total dollars than the
graze-out system where P was applied but not where P was omitted. Production expenses
increased primarily because of the cost of the P fertilizer with other costs remaining essentially
the same. Land rent increased with P applications because total income increased, but the
landlord did not share the fertilizer cost in our lease agreement.

    Total returns per acre averaged $13 below costs in the graze-plus-grain system and $26
below costs in the graze-out system. In the graze-plus-grain system the deficit ranged from $8
per acre where P was surface applied to $17 per acre where no P was applied. These results
follow the same trends as those obtained in 1999-2000, where economic losses in the graze-
plus-grain system averaged about $15 per acre and losses in the graze-out system averaged
$35 per acre. No government payments were included in the economic analysis.

Although 2001-2002 was the third year of this study, only two years produced forage for grazing
during the fall months. In the second year, wheat planting was delayed by rains until December
so




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    only grain data were obtained. The study is currently being conducted again to obtain the
third year of animal performance data.

                                           SUMMARY

        Three soil fertility practices were applied in three replications to the same nine 25-acre
pastures for three consecutive years to determine P and P placement effects on the economics
of forage, beef, and grain production under two management schemes. Grain production was
increased 5 to 8 bushels per acre only during the third year of the study. Fall forage production
was increased by P fertilizer in the two years when timely fall planting was possible. Forage
responses were readily visible during the dry periods in fall but disappeared as rains occurred in
late winter to early spring. However, forage yield data show that responses to P applications
continued throughout the year. There was no benefit to deep placement (6 to 8 inches) of N
and P fertilizers rather than broadcasting the fertilizer and incorporating lightly with a field
cultivator.

       Economic analyses show financial losses with each soil fertility practice under both
grazing schemes. By grazing only from December through February and subsequently
producing a grain crop, beef production per acre increased by 19 and 30% during the two years
by the addition of P. Economic losses averaged $10 to $15 per acre. By grazing the wheat
from December until maturity in May and not producing grain, beef production per acre
increased 39 and 21% during the two years, due to P application. However, economic losses
averaged $25 to $35 per acre.

        During this study, wheat prices ranged from $2.67 to $2.90 per bushel, contributing to
economic losses. Beef gains returned 32 and 334 per pound during the two years when grazing
occurred. Additional returns from owning the cattle to capture the total increase in value of the
cattle were not included in the economic analysis. Farm support payments were also omitted.
When the third year of production data is complete, sensitivity analyses will be used to evaluate
effects of various management scenarios, production levels, and commodity prices on
profitability.


                                      LITERATURE CITED

Adams, N.J., U.U. Alexander, S.J. Bevers, and E.P. Boring, III. 1989. District III interdisciplinary
        wheat and stocker management - Three year summary. Texas Agric. Extension Service.
Miller, T. 1998. Deep phosphorus banding in winter wheat-a risk management tool for the
        southern Great Plains. Better Crops 82:26-28.
Pinchak, W.E., W.D. Worrall, S.P. Caldwell, L.J. Hunt, H.J. Worrall, and M. Conoly. 1996.
        Interrelationships of forage and steer growth dynamics on wheat pasture. J. Range
        Manage. 49:126-130.
Ralphs, M.H., D. Graham, M.L. Galyean, and L.F. James. 1997. Research observation:
        Influence of over-wintering feed regimen on consumption of locoweed by steers. Journal
        of Range Management 50:250-252.
Redmon, L.A., G.W. Horn, E.G. Krenzer, Jr., and D.J. Bernardo. 1995. A review of livestock
        grazing and wheat grain yield: boom or bust? Agron. J. 87:137-147.
Schlehuber, A.M., and B.B. Tucker. 1967. Culture of wheat. In K.S. Quisenberry and L.P. Reitz
        (ed.) Wheat and Wheat Improvement. ASA, CSSA, SSSA, Madison, WI.




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Shroyer, J.R., K.C. Dhuyvetter, G.L. Kuhl, D.L. Fjell, L.N. Langemeier, and J.O. Fritz. 1993.
      Wheat pasture in Kansas. Cooperative Extension Service Report C-713, Kansas State
      University, Manhattan, Kansas.
Texas Agricultural Statistics. 1998. Texas Agricultural Statistics Service, USDA, Texas Dept.
      Agric. Bulletin 257, September 1999. Austin, TX

                                  INDUSTRY SPONSORS

Fluid Fertilizer Foundation, Goodpasture, Inc., Poole Chemical Co., Inc., IMC, Simplot
       Fertilizers, Foundation for Agronomic Research, PPI, Darr Equipment Co., and Texas
       Wheat Producers Board.




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Table 1. Mean cumulative forage production in grazed pastures of >Lockett= wheat receiving
three soil fertility practices during two years at Vernon, TX.
Fertilizer
Treatment                        Dec.           Jan.            Feb.           Mar.            Apr.           May
                                                              1999 - 2000
                              ---------------------------------lb/acre/-----------------------------------------
N surface                       1160            1400            1590           2195           3690            4790
NP surface                      1440            1610            1815           2450           4235            5415
 NP deep                        1160            1520            1755           2440           4325            5510
                                                               2001 - 2002
N surface                        675            1045             1285      1745               3985            4205
NP surface                       950            1625             2115      2775               5470            5505
 ND deep                         735            1260             1480      1945               4980            4980


    2-YEAR                      1020            1410            1675           2260           4450            5070
     MEAN
/
    Forage yields were estimated as the difference between forage weights in caged and uncaged areas taken one
    month apart. Each data point is the mean of five observations in each of three 25- acre pastures.



Table 2. Grain and beef production from wheat grown with three soil fertility practices in a
         graze-plus-grain management system during two years at Vernon, TX.
          Fertilizer                            Beef Gain Per                           Stocking            Grain
         Treatment                Head/Day             Head              Acre             Rate              Yield
                                    ----------------------lb--------------------         A/head/            bu/A
                                                                    1999 - 2000
         N surface                     2.03             163              85                1.92               25
         NP surface                    2.69             215             101                2.13               25
          NP deep                      2.53             202             107                1.89               27
                                                                      2001-2002
                                                                    2001 - 2002
         N surface                     2.59             202             53                 3.81               20
         NP surface                    2.55             199             69                 2.88               28
          NP deep                      2.79             217             61                 3.56               25
/
    Stocking rate is the average number of acres (A) per animal during December-February.




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Table 3. Beef and forage production from wheat grown with three soil fertility practices in a
graze-out management system during two years at Vernon, TX.
                                                                                                         Ungrazed
Fertilizer                                     Beef Gain Per                          Stocking            Forage
Treatment                            Head/Day Head                 Acre                 Rate               Yield
                                       ----------------lb------------------            A/head /              lb/A /
                                                 1999 - 2000
           N surface                 2.41          369                180                2.05                4775
           NP surface                2.57          359                250                1.44                5980
            NP deep                  2.70          374                219                1.70                5520
                                                   2001 - 2002
           N surface                  2.39          383               219                1.75                4990
           NP surface                 2.43          388               265                1.46                6010
            NP deep                   2.44          390               230                1.54                4720
/
     Stocking rate is the average number of acres (A) per animal during December-May.
/
     Ungrazed forage was measured in May within cages that had never been grazed.



Table 4. Mean economic returns from phosphorus fertilization of wheat pasture in 2002 at
        Vernon, TX.
                                  Grain + Graze                                         Graze-Out

                       N              N+P               N+P               N                N+P                N+P
                     Surface         Surface            Deep            Surface           Surface             Deep
                      ---------------------------------------------$/acre-----------------------------------------------
      Income
       Grain +          57              80                73                0                 0                 0
      Cattle ++         17              23                20                73                88
                                                                                                               76
    Total Income        75              103               93                73                88               76
Expenses                   Production
 Production             74          87                    85                75                88               84
Land Rent +++           18          24                    21                22                25               21

 Total Variable
     Costs              92              111               106               97               113               105
 Return Above
   Variable             -17              -8               -13              -24               -25               -29
    Costs
+ Grain price was $2.90/bushel .
++ Cattle price was $0.33 per lb. gain.
+++
    Land rental was 1/3 of income minus 1/3 of seed and harvest cost.




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