AY-244-W

CROPS

Purdue University
Cooperative Extension Service
West Lafayette, IN 47907



WHEAT PRODUCTION AND FERTILIZATION IN INDIANA



C. Mansfield and S. Hawkins, Extension Agronomists, Purdue University


Indiana's climate and soil are suitable for producing high quality soft red winter wheat. High yields of winter wheat are attainable when sound management practices are employed. Use of improved varieties, correct seeding rates, proper fertilization, and weed and disease control are all necessary to attain high production of soft red winter wheat in Indiana.

This publication is aimed at helping Hoosier farmers realize optimum wheat yields. It presents several varieties and what to consider in selecting the appropriate ones. It also discusses the management steps related to proper seeding rates and planting dates, fertilization practices, and controlling weeds and disease pressure.

Varieties

No single soft red winter wheat variety has all the desirable characteristics; rather, each has certain advantages. Winterhardiness, yielding ability, straw strength, height, grain quality, and resistance to Hessian fly and diseases (particularly Septoria leaf and glume blotch, powdery mildew, and leaf rust) all must be considered when choosing a variety. At high nitrogen rates resistance to powdery mildew is especially important.

Characteristics of several publicly developed varieties for Indiana are shown in Table 1. Privately owned varieties and hybrids are also available; the owners should be consulted for a description of characteristics and adaptation recommendations.

Most public and private wheat varieties are evaluated annually by Purdue University at various locations throughout Indiana. A summary of test results for up to 3 years is presented in the Agricultural Experiment Station Bulletin titled Performance of Public and Private Small Grains in Indiana, which becomes available each year in the late summer from your county Cooperative Extension Service office.

When selecting wheat varieties, it is suggested that you limit your choices to those specifically adapted to Indiana conditions. Some late- and very late-maturing lines may produce exceptionally high yields in certain years; but if they lack winterhardiness, their yields can be greatly reduced in years having bad winters. With adapted varieties, on the other hand, yield potential is fairly consistent from year-to-year.

Date of Planting

Soft red winter wheat should be planted within the two-week period following the Hessian fly-free date, which ranges from September 22 across the northern tier of counties in Indiana to October 9 in the extreme southern part of the state (Figure 1). There is no genetic resistance in currently available wheat varieties to the Biotype-L Hessian fly. Populations of this biotype have been steadily increasing over the past several years, and it is now a real threat to early-planted wheat. Early planting can also lead to excessive fall growth which could increase susceptibility to winter-kill as well as increased problems with several diseases.

Figure 1. Average Hessian fly-free dates in Indiana.

The disease take-all (a soilborne disease) and seedling blight diseases can be more severe with early planting dates. When soil temperatures are relatively high (i.e., <60 °F) there is increased activity by disease organisms, and, therefore, a greater possibility of fall seedling blights. However, even timely planted wheat that is infected with scab or Septoria can succumb to seedling blights in warm soils.

Table 1. Summary of Characteristics of Recommended and Acceptable Publicly Developed Wheat Varieties1.


        
                                                             Resistance to   
                           --------------------------------------------------------------------------------------------
        Days				
        later   Plant              Winter                             	Septoria   Spindle     Barley   
        than    height   Standing  hardi-    Leaf     Powdery   Loose   leaf       streak      yellow   Take-   Hessian
Variety Clark   (in.)    ability   ness      rust     mildew    smut    blotch     mosaic      dwarf    all     fly
------------------------------------------------------------------------------------------------------------------------
Adder     5        34      Excel.   Excel.   Excel.    Good        -      Good      Good        Fair    Good    Fair
Adena     4        33      Excel.   Good     Fair      Fair      Good    Good       Good        Fair    Good    Poor
Arthur    2        37      Good     Good     Fair      Fair      Good    Poor       Fair        Poor    Poor    Poor 
Arthur71  3        37      Fair     Good     Fair      Fair      Good    Poor       Fair        Poor    Poor    Fair
Auburn    4        36      Excel.   Excel.   Excel.    Excel.       -    Excel.     Fair        Fair    Good    Fair
Becker    5        32      Excel.   Good     Fair      V. poor      -    Fair       Good        -       Fair    Poor
Caldwell  2        36      Excel.   Good     Good      Fair         -    Good       Fair        Fair    Poor    Fair
Clark     0        37      Excel.   Good     Fair      Good         -    Good       Excel.      Fair    Good    Fair
Compton   5        36      Good     Good     Excel.    Excel.       -    Good       Good        Fair    Fair    Fair
Fillmore  6        37      Good     Good     Good      Fair         -    Good       Poor        Fair    Poor    Fair
Hart      3        36      Fair     Poor     Poor      V. poor      -    Fair       Excel.      Fair    Fair    Poor
Pike      5        36      Fair     Poor     Poor      V. poor      -    Good       Good        Fair    Fair    Poor
Roland    4        35      Excel.   Fair     Good      Fair         -    Fair       Good        Fair    Fair    Poor
Scotty    4        36      Excel.   Good     Fair      Good         -    Good       Good        Poor    Fair    Poor
Titan     5        38      Good     Fair     Good      Good      Good    Fair       Excel.      Fair    Good    Poor
Tyler     6        38      Good     Fair     Poor      Excel.       -    Fair       Good        Fair    Fair    Poor
------------------------------------------------------------------------------------------------------------------------
1 Rating data from Purdue University field, laboratory, and nursery
plots.

2 All varieties are susceptible to currently prevalent biotype L of
Hessian fly.

Certain soilborne virus diseases such as wheat mosaic and wheat spindle streak mosaic may be more severe with early-planted wheat. Fall infection with aphid-transmitted barley yellow dwarf virus can also be a serious problem when wheat is planted before the fly-free date, because of abundant aphid populations.

Wheat cannot always be planted within 2 weeks after the fly-free date because of adverse weather conditions, late harvest of previous crop, etc. While late-planted wheat may yield adequately, grain production is often reduced 10-20%. Twenty-five percent of the time grain yields from late-planted wheat will be severely reduced. Late-planted wheat often does not tiller adequately in the fall and is less winter hardy; in addition, it may be more susceptible to winter heaving.

In summary, wheat should be planted within 2 weeks following the fly-free date, but can also be planted up to within 30 days after the fly-free date for your area.

Table 2. Seeding Rates for Winter Wheat Based on Seed Size*.


                              Desired Population        
                          ____________________________________________

Number of       Seed         1.1**         1.3**        1.5**
seeds/lb.       size         25^           30^          35^
______________________________________________________________________

                                   (lb. seed/a.)
                          ____________________________________________

10,000          large        120           145          165
12,000          large        100           120          140
14,000          medium       85            100          120
16,000          small        75             90          105
______________________________________________________________________
* Seeding rates adjusted to 90% field emergence.

** Million plants per acre.

^  Plants per square foot.

Seed Source, Seeding Rate, and Plant Population

When choosing from among the many public and private varieties which are available, the use of certified seed is important so that you know the exact identity of the variety you are buying. Seed certification guarantees that the seed purchased will contain the traits that the plant breeder intended it to have, and that the seed will be high quality.

Sometimes, you may want to save your own seed to use for the next crop. However, if the seed was contaminated with smut it should not be planted. Where smut was not a problem, the seed should be professionally cleaned in order to remove scabby and other diseased or shriveled kernels, and it should be treated with a fungicide in order to avoid seedling blights. A germination test should also be run as a measure of seed quality. Good quality seed should have greater than 85-95% germination. Germination tests are available to growers through the seed laboratory at Purdue University.

The seeding rate for soft red winter wheat should be adjusted according to seed size. Seed size can vary from 10,000 to 16,000 seeds/lb., and seedsmen should have this information available. Table 2 lists the different planting rates for the different sized seeds based on 1.1, 1.3, and 1.5 million plants/acre. For example, to achieve 30 plants per square foot with a large sized seed (12,000 seeds/lb.) plant 120 lb./acre. With a medium sized seed (14,000 seeds/lb.) only 100 lb./acre is needed to achieve the same plant population given equal germination and field emergence.

The optimum plant population for soft red winter wheat is 30 to 35 plants per square foot, that is 1.3 to 1.5 million plants/acre. Seeding rates to achieve plant populations of 30 plants per square foot are adequate to produce 90-100 bu./a. yields under ideal environmental conditions. If planting into areas where winter heaving and winter kill are problems, then the seeding rate should be 35 plants per square foot. Seed should be sown 3/4 to 1 1/2 inches deep.

Fertilization

Providing a good fertility program is part of obtaining the potential yield that can be expected of the soil-climate-management combination put together by a producer. Understanding the yield potential and limitations of specific soil types in a field is key to obtaining soil samples by soil type or soil management group and for setting realistic yield goals. Periodic soil testing and yield records for each field help determine the fertilizer needs and allow the producer to evaluate options.

The soil pH or meter pH is used to determine if lime is required. A soil pH below 6.0 in small grain production is usually the decision point where lime is recommended. Once the decision is made to apply lime, then the lime index or buffer index is used to determine the rate of lime per acre.

If wheat is being used as a nurse crop for establishing alfalfa, sweet clover, or birdsfoot trefoil, then adequate lime needs to be applied to achieve a soil pH of 6.8 to 7.0. These legumes require a higher pH for optimum production. When sending in a soil sample for a field that is to be planted to wheat and then one of these legumes, be sure to indicate this on the information form sent to the lab in order to get a proper lime recommendation.

Applying lime prior to planting wheat may not be timely if a previous crop needs to be removed and plowing or chiseling is to be used for incorporation. Planning lime applications may prove more convenient if the whole crop rotation cycle is considered and sufficient lime is applied to maintain adequate soil pH throughout the rotation.

In the past, to many farmers, wheat fertilization has meant just nitrogen; but phosphorus and potassium are also very important for growth and tillering. Fertilizer rates for these nutrients should be based on a current soil test plus your expected yield goal for wheat. Phosphorus and potassium fertilizer recommendations are made in Indiana based on the Bray P1 phosphorus soil test and the exchangeable K soil test, respectively. For best results, soils should be tested every two to four years, and the entire amount of fertilizer P and K that is recommended should be applied prior to or at seeding since topdressing these nutrients is not effective.

Table 3. Recommended Phosphorus Fertilizer Rates for Wheat at Various Yield and Soil Test Levels.

        
Bray P1 soil         Interpretation        Yield Potential (bu./a.)
 					---------------------------------------
Test Level                                30-44   45-54   55-64   65-74   >75
-----------------------------------------------------------------------------------
 ppm        lb./a.     
------------------------------------------------------------------------------------     
                                                lb. P2O5 to apply per a.
                                           ___________________________________

0-5          0-10       Deficient           90     120     120     140    140
6-10        11-20       Deficient           60      90      90     110    110
11-15       21-30       Deficient           30      60      60      90     90
16-25       31-50       Adequate            20      30      30      60     60
26-50       51-100      Optimum             20      20      20      20     20
51-150     101-300      High                 0       0       0       0      0
>150          >300      Excessive            0       0       0       0      0
------------------------------------------------------------------------------------  

Table 3 gives the recommended P2O5 rate for various soil test levels and potential yields. Soils with Bray P1 tests below 15 ppm or 30 pounds per acre are considered deficient and require phosphorus fertilizer for optimum wheat production. The recommended rate of P2O5 shown in the table should be applied annually at or before planting. Following these recommendations should increase the P soil test to the adequate range in three to five years.

Soils with Bray P1 tests from 16 to 25 ppm or 31 to 50 pounds per acre are considered adequate for wheat production. The recommended rate of P2O5 should be applied annually or combined with the recommended rates for rotational crops and applied every two or three years, prior to wheat seeding.

Bray P1 soil tests from 26 to 50 ppm or 51 to 100 pounds per acre are considered optimum. At this range of soil test levels the soil contains adequate residual P to meet the needs of 4 to 12 successive crops. However due to the high P response found with winter wheat, a small amount of P should be applied at seeding to encourage early tillering and winter hardiness. Farmers who wish to maintain soil tests at this level can do so by applying P2O5 at rates equivalent to those recommended for the same yield potential at adequate soil test levels.

Bray P1 soil tests from 51 to 150 ppm or 101 to 300 pounds per acre are considered high. No P fertilizer is needed for wheat production at this soil test level. There are no agronomic reasons to apply fertilizer to maintain soil tests at these levels.

Bray P1 soil tests above 150 ppm or 300 pounds per acre are considered excessive. While few adverse effects of these high levels to wheat are known, the potential for adding P to ground and surface waters increases at these levels. Soils with these P soil test levels would not be recommended as sites for the disposal of P-containing manures or sludges.

Table 4. Recommended Potassium Fertilizer Rates for Wheat at Various Yield and Soil Test levels.

Exchangeable K         Interpretation          Yield Potential (bu./a.)
                                     	    -------------------------------
Soil Test Level                             30-44  45-54  55-64  65-74  >75
---------------------------------------------------------------------------
  ppm           lb./a.  
---------------------------------------------------------------------------
                                               lb. K2O to apply per a.
                                            -------------------------------  
0-40             0-80      Deficient         90     120    120    120  120
41-75           81-150     Deficient         60      90     90     90   90
76-105         151-210     Deficient         30      60     60     60   60
106-150        211-300     Adequate          20      30     30     30   30
150-200        301-400     Optimum            0       0      0      0    0
201-300        401-600     High               0       0      0      0    0
>300              >600     Excessive          0       0      0      0    0
---------------------------------------------------------------------------

Table 4 gives the recommended K2O rate for various soil test levels and yield goals. Soils with exchangeable K soil tests below 105 ppm or 210 pounds per acre are considered deficient and require potassium fertilizer for optimum wheat production. The recommended rate of K2O given in the table should be applied annually at or before planting. Following these recommendations should increase the K soil test to the adequate range in three to five years.

Soils with Exchangeable K soil tests from 106 to 150 ppm or 211 to 300 pounds per acre are considered adequate for wheat production. The recommended rate of K2O given Table 4 should be applied annually or combined with the recommended rates for wheat seeding. Following these recommendations should result in little change in soil test levels over time.

Exchangeable K soil tests from 150 to 200 ppm or 301 to 400 pounds per acre are considered optimum. At this range of soil test levels the soil contains adequate residual K to meet the needs of 4 to 12 successive crops. Farmers who wish to maintain soil tests at this level can do so by applying K2O at rates equivalent to those recommended for the same yield potential at adequate soil test levels.

Exchangeable K soil tests from 201 to 300 ppm or 401 to 600 pounds per acre are considered high. No K fertilizer is needed for wheat production at this soil test level. There are no agronomic reasons to apply fertilizer to maintain soil tests at these levels.

Exchangeable K soil tests above 300 ppm or 600 pounds per acre are considered excessive. While few adverse effects of these high levels to wheat are known, the potential for adding K to ground and surface waters increases at these levels. Soils with these K soil test levels would not be recommended as sites for the disposal of K-containing manures or sludges.

Nitrogen (N) rates are based on expected yield goals and soil texture. Regardless of soil type, 15 to 30 pounds of N should be applied at seeding, with the balance topdressed as close as possible to the time regrowth begins in the spring. Nitrogen rates for topdressing wheat are summarized in Table 5. Consider splitting the N topdress application when striving for high yield goals on sandy soils that have low cation exchange capacity (i.e., CEC > 6meq/100g) in order to avoid excessive N loss from leaching. The first half of the N should be applied as regrowth begins, with the balance being applied at early boot stage.

If topdressing is delayed, nitrogen can still be applied up to heading time. However, fertilizer response by wheat is reduced at later growth stages; therefore, both the N rates and yield goals should be reduced slightly.

Choosing a Nitrogen Fertilizer Material

Ammonium nitrate is the preferred topdressing material. But because it has been in short supply, urea (45-0-0) or 28% N solution are more widely used at present. All three materials are well-suited for wheat, particularly at the normal topdressing times in late winter or early spring. Other acceptable materials include ammonium sulfate (21-0-0) and calcium nitrate (15-0-0).

If topdressing has to be delayed until the wheat is well-jointed, the preferred material again is ammonium nitrate, followed in order of preference by ammonium sulfate and urea. A 28% solution may be used but is not preferred for late topdressing, since it can burn actively growing tissue. Solid stream nozzles placed on 10- to 15-inch centers may reduce the leaf burn from 28% N solution applications. (For a more thorough discussion of nitrogen fertilizers, see Purdue Extension Publication AY-204, Types and Uses of Nitrogen Fertilizers for Crop Production, available at your county Extension office.)

AY-204

An alternative to topdressing wheat is to fall apply all of the N in an ammonium form stabilized with a nitrification inhibitor. Purdue research has shown that anhydrous ammonia with a nitrification inhibitor injected at a 15- to 20-inch knife spacing gives results as good as topdressing in most years. Although not well-suited for light-colored sands, this system may be worth trying on other soils, particularly if topdressing is a problem. To determine proper rates for fall-applied stabilized ammonia, simply add 20 pounds to the recommended topdress rate figures in Table 5. Be sure to adjust N rates for any N applied with the P fertilizer.

Nitrogen in fall applications can also be applied as urea or 28% solution stabilized with a nitrification inhibitor. But research to date has not found these materials as effective as stabilized ammonia.

Table 5. Recommended Topdress Nitrogen Fertilizer Rates for Wheat at Various Yield Levels and Soil Textures.

Cation                         Nitrogen rate when
exchange                    bu. per a. yield goal is--    
capacity          30-44    45-54     55-64     65-74     75-85    85+
-----------------------------------------------------------------------
meq/100g                               lb./a.
-----------------------------------------------------------------------
<6                 50        60        70        80       90     100
6-10               40        50        60        70       80     100
11-30              30        40        50        60       70      90
>30                20        30        40        50       60      60
-----------------------------------------------------------------------

Fertilization for Double-cropping

If planning to plant no-till double-crop soybeans following wheat, both crops need to be fertilized in the fall prior to wheat establishment. The potential yield of both crops needs to be considered when determining fertilizer needs. Phosphorus and potassium recommendations for double-cropping are presented in Table 6 and they are based on varying expected wheat yields plus a 35-bushel-per-acre soybean yield. By using Tables 3 and 4 in this publication and the appropriate tables in ID-179, Corn and Soybean Field Guide, double-crop fertilizer rates can also be calculated for higher potential soybean yield. The amount of phosphorus and potassium to be applied is the sum of the amounts recommended for both crops at the current soil test level.

Weed and Disease Control

Weeds are most commonly a problem in soft red winter wheat during the spring growing period. Wild garlic is the main concern and must be controlled (when actively growing) by a foliarly absorbed herbicide. It is likely that wheat will also be actively growing at this time, and it is not recommended that liquid nitrogen be used for the carrier because of excessive leaf burn to young wheat plants.

Fungicides can be used to partially control certain head and foliar disease problems such as Septoria leaf and glume blotch or powdery mildew. Powdery mildew is a foliar disease that is a problem on certain varieties during early- to mid-spring. Septoria leaf blotch and Septoria glume blotch can be active throughout the spring. The Septoria leaf blotch organism affects only the foliage; however, Septoria glume blotch affects both leaves and heads. Septoria glume blotch has caused significant grain yield reductions and poor seed quality of soft red winter wheat in recent years. A timely fungicide application may help to reduce the severity of this disease. Another common head disease of soft red winter wheat is head scab. There is no genetic resistance to head scab of wheat in present varieties, nor is fungicide application effective for its control. Severity of head scab infection depends almost entirely on environmental conditions at anthesis. For specific information on fungicide products, rates, and timing of application contact your county Extension agent.

Summary

Producing a high-yielding wheat crop involves many management practices. Choosing several appropriate varieties, using high quality seed at the correct planting rate, sowing after the Hessian fly-free date, establishing a good stand, proper fertilization, and weed- and disease-pressure control are all key ingredients to realizing consistently high grain yields.

Table 6. Recommended Phosphorus and Potassium Fertilizer Rates for Double-crop Wheat Followed by Soybeans at Various Yield and Soil Test Levels.

                                  P205 and K20 rates when wheat/soybean
Soil Test  Bray P 1                      bu./a. yield goal is--
Level      or Ex K             35/35   45/35    55/35   65/35    75/35
--------------------------------------------------------------------------
            ppm    lb./a.  
-------------------------------------------------------------------------- 
                                       lb. to apply per a.                                       
		                 ----------------------------------------
Deficient  0-5     0-10  P205   150     180      180     200      200
           0-40    0-80  K20*   190     220      220     220      220


Deficient  6-10   11-20  P205   110     140      140     160      160
          41-75   81-105 K20*   140     170      170     170      170


Deficient 11-15   21-30  P205    70     100      100     130      130
          76-105 151-210 K20     80     110      110     110      110


Adequate  16-25   31-50  P205    50      60       60      90       90
         106-150 211-300 K20     80      70       70      70       70

Optimum   26-50   51-100 P205    20      20       20      20       20
         150-200 301-400  K20     0       0        0       0        0

High      51-150 101-300 P205     0       0        0       0        0
         201-300 401-600  K20     0       0        0       0        0

Excessive   >150    >300 P205     0       0        0       0        0
            >300    >600  K20     0       0        0       0        0
______________________________________________________________________
*       If CEC < 6meq/100g do not apply more than 150 lb. K20/a.
______________________________________________________________________


Rev 11/92

Cooperative Extension work in Agriculture and Home Economics, State of Indiana, Purdue University and U.S. Department of Agriculture cooperating: H.A. Wadsworth, Director, West Lafayette, IN. Issued in furtherance of the acts of May 8 and June 30, 1914. The Cooperative Extension Service of Purdue University is an equal opportunity/equal access institution.