North Dakota Fertilizer Recommendation Tables and Equations

Based on Soil Test Levels and Yield Goals

�SF-882 May 2007

D.W. Franzen, Extension Soil Specialist
 

Contents

 Nutrient Recommendations
 

Table 2.	Alfalfa
Table 3.	Barley, feed
Table 4a.	Barley, malting in cooler, moister climates
Table 4b.	Barley, malting in warmer, drier climates
Table 5.	Buckwheat
Table 6.	Canola
Table 7.	Clovers(alsike, red, birdsfoot trefoil, grass-legume)
Table 8.	Corn, grain and popcorn
Table 9.	Corn, silage
Table 10.	Corn, sweet
Table 11.	Crambe
Table 12.	Dry bean (pinto, navy, other)
Table 13.	Flax
Table 14.	Forage/hay grasses, established, irrigated, new seedings, native grass
Table 15.	Millet and canary seed
Table 16.	Mustard
Table 17.	Oat
Table 18.	Pea, field, lentil and chickpea
Table 19.	Potato
Table 20.	Safflower
Table 21.	Sorghum, grain
Table 22.	Sorghum, forage, sudangrass
Table 23.	Soybean
Table 24.	Sugar beet
Table 25.	Sunflower
Table 26.	Wheat, spring, durum, winter and rye

The following soil test recommendation tables are based on field research data obtained in North Dakota, South Dakota, western Minnesota and the Canadian Prairie Provinces. In the case of some crops, data in the literature also were used to supplement data available from this area. These tables were developed in cooperation with South Dakota State University and the University of Minnesota under the Tri-State Recommendation Program. Note that phosphorus and potassium soil test results in these tables are in parts per million (ppm). Parts per million times two is equal to pounds per acre for a 0- to 6-inch deep sample core. This conversion will help interpretation of data from laboratories that provide results in units other than ppm.

This publication contains changes from previous publications. Please dispose of older editions. Changes in comparison to previous tables were made based on new or re-evaluated data.

The major changes are:

1. Dry bean nitrogen (N), phosphorus (P) and potassium (K) recommendations

2. Malting barley N recommendations in drier, warmer areas (mostly in the west)

3. Canola N recommendations

Recommendation Tables

Fertilizer needs should be determined after carefully evaluating the current fertility level of the soil and the nutrient needs of the crop to be grown, and setting realistic yield expectations. We strongly suggest that yield expectations be based on yield potential for a field or a region. Recent research has shown that more productive areas of fields require less fertilizer, particularly N, than less productive areas of the field because they tend to be higher in organic matter and have a higher seasonal moisture content. The exception to this would be saline areas that commonly are high in residual N. Several of our N recommendations are "capped" at a maximum rate. In years that support higher yields than our N recommendation formulas indicate, our data show that greater N release from the soil will support these higher yields without requiring additional supplemental N fertilizer.

Nitrogen

Nitrogen (N) recommendations for all crops except some legumes are based on the amount of nitrate-N (NO₃-N) in the top 2 feet of soil and the yield potential. Nitrogen fertilizer recommendations are not adjusted based on method of placement, but are adjusted for previous crop and depth of sampling. To determine the amount of recommended fertilizer N, subtract the amount of NO₃-N in the soil as determined by soil test and N-credit from the previous crop, if applicable, from the total amount of available N needed for a particular yield goal and crop.

An Example

Your NDSU soil test shows that you have 55 pounds of NO₃-N present in the soil to 2 feet. Your yield potential is about 40 bushels per acre (bu/A) of spring wheat. The amount of nitrogen recommended to support a 40-bushel yield is 100 pounds of N/acre. The difference between 100 pounds (from the N fertilizer recommendation table for wheat) and 55 pounds (the soil test) is 45 pounds of N. Therefore, the N
recommendation is 45 pounds of N/acre.

Adjusting N Recommendations

In a preplant NO₃-N soil testing program, certain adjustments need to be made for the apparent contribution of N from some previous crops:

Previous Crop N Credits

Some crop residues have a lower carbon/nitrogen ratio (C/N ratio) than others, which results in a release of plant-available N through rapid decomposition. Also, the mass of residue of some crops is smaller than others (dry bean compared with wheat or corn, for example). Evidence also shows that some crops (soybean) may accelerate the normal N mineralization rate from organic matter. Nitrogen availability is greater after crops with lower C/N ratio (sugar beet, alfalfa) and crops having a lower mass of residue (soybean, dry bean) with less ability to tie up N during decomposition. We suggest that the following N credits be subtracted from crop N recommendations.

Credits

Second Year N Credits

Half of credit given for the first year for sweet clover and alfalfa, none for other crops.

Depth Adjustments

The original data for calibration of the NO₃-N test was based on soil samples taken to a depth of 5 feet. Sampling beyond 2 feet improved nitrogen recommendations somewhat, but in the late 1960s, researchers decided that the extra effort to sample to a depth of 3 or 4 feet was not practical or necessary for most crops. Drought and application of excess N, however, may result in a buildup of available N below 2 feet. When fields are tested for N each year and only the recommended amount of N is applied, an accumulation of nitrogen below 2 feet is unlikely.

Sugar beet is the most likely crop to be sampled to the 4-foot depth, but adjustments are not necessary in N calculations. Recommendations for sugar beet for 2-foot and 4-foot sampling are given in Table 24. If deeper sampling is conducted to refine recommendations or screen for problems in malting barley, sunflower or safflower, the following adjustments would apply:

1. If the amount of NO₃-N in the 2- to 4-foot depth is less than 30 pounds NO₃-N/A, do not adjust the recommendation.

2. If the amount of NO₃-N in the 2- to 4-foot depth is more than 30 pounds NO₃-N/A, reduce the N recommendation by 80 percent of the amount greater than 30 pounds per acre (lb/A). For example, if there are 50 pounds NO₃N/A in the 2- to 4-foot depth, reduce the N recommendation by 16 pounds N/A (80 percent of 50 pounds N/A less 30 pounds N/A, or 20 pounds).

Phosphorus and Potassium

The phosphorus (P) and potassium (K) recommended in these tables is the amount to be applied as a broadcast application. Since banded fertilizer generally is used more efficiently in the year of application, the amount of P₂O₅ and K₂O in the tables can be reduced by one-third when banding. Data from field trials in drier or cooler years indicate that small grains, corn and canola will respond to seed-placed or side-banded P fertilizer, even on soils testing medium to high in phosphorus.

Some crops are very sensitive to fertilizer salt injury. No fertilizer is recommended with the seed for these crops in 15-inch rows or wider. Fertilizer-sensitive crops include all legumes, such as soybean, pea, dry bean and others. Consult individual soil fertility publications for each crop for more information. For information regarding fertilizer rate limits with the seed in small grains, consult NDSU Extension publication EB-62.

Under no-till, and especially ridge-till systems, corn and soybean have responded to banded K even when soil test levels for K are high.

Broadcast recommendations of P or K for low and very low testing soils include buildup P and K rates. When rates are reduced, soil test levels are not  increased through time. A long-term P and K strategy should include buildup to medium soil test levels at some future date. Near maximum yield potential is achieved only when these soil test levels are reached. Application of less than maintenance rates will result in a decline in P and K levels through time and an accompanying decline in the productivity of most crops.

Sulfur

Sulfur (S) deficiency is most likely to occur on sandy soils throughout the state and on well-drained, medium-textured soils. It appears most often on higher landscape positions with a thin-surface organic-matter layer ("A" horizon) and coarse soil texture (loam to sand and gravel). Our current S soil test characterizes the S status of the soil very poorly. Having the test underestimate or overestimate the available S in soil is common for a variety of reasons. A better plan often is to note the texture, organic-matter content, landscape position and rainfall in the past year as a predictor of S need than to soil test.

If a soil test is nonetheless desired, since sulfate-S (SO₄-S) is quite soluble, the top 2 feet of soil should be sampled, using a procedure similar to the one recommended for N and chloride (SF-880). If the amount of SO₄-S is less than 16 lb/A in the top 2 feet, certain crops may respond to S fertilizer. Canola is especially responsive S. In canola, a high composite SO4-S soil test result would result in a recommendation of 10 to15 pounds of S/acre, while with a low to medium SO₄-S test result, the recommended rates would be 20 to 30 pounds of S/acre. Sulfur is recommended for canola on high testing soils because of the variability of soil S levels, the poor relationship of S soil analysis with S responses and the tremendous effect that S deficiency can have on this crop. Sulfur is not recommended on high testing soils for other crops.

Chloride

The chloride (Cl) soil test is calibrated only for small grains, although a few responses also have been seen in corn within the U.S. In general, responses to Cl in small grains have been in the range of 1 to 6 bu/A on responsive sites. The Cl recommendation is determined by subtracting the amount of Cl found in the top 2 feet of soil from 40 lb/A, although most of the yield response comes generally from the first 10 to 15 lb/A of Cl applied. The most commercially available and cheapest source of Cl fertilizer is 0-0-60 (Potassium chloride, muriate of potash) which contains
approximately 50 percent Cl.

Other Nutrients

The DTPA analysis is used to test soils for plant-available zinc (Zn), iron (Fe), manganese (Mn) and copper (Cu). Calibration data are available only for Zn on Zn-sensitive crops, such as corn, soybean, sorghum, potato, flax and edible bean, and Cu on wheat/durum and barley. Micronutrient requirements are crop-specific. Additional crops would not be expected to respond to Zn or Cu if not listed above.

Zinc

When corn, soybean, sorghum, potato, flax or edible bean are to be grown on a field testing low to very low in Zn, the recommendation is to apply 10 lb/A of Zn as zinc sulfate in a broadcast application, or one-third of that rate as a band. Zinc is especially required in these crops if high levels of broadcast P or a starter P fertilizer is applied when soil Zn levels are low. Water solubility is important in efficient dispersion and uptake. Also, the application is more likely to achieve a first-year response to zinc sulfate if the fine granular formulation of the product were used instead of the MAP or DAP-sized granules usually available.

A fine granular application should be made using a fine-granular applicator similar to those used in the past to apply granular herbicide formulations. The distribution of large granules may not be adequate to supply all plants with Zn. A broadcast application of zinc sulfate should correct a Zn deficiency for four to five years.

Zinc chelates at suggested manufacturer rates also may be used, but are relatively expensive per pound of plant food and offer no residual soil buildup. Banded chelates at 1 pint to 2 quarts/A often are used at planting. Foliar applications of zinc chelate and other soluble Zn fertilizers at low rates also are effective for correction of deficiencies for a single season. No Zn is recommended on fields testing medium or above or on fields testing very low, low or medium if the crop to be grown is not a Zn-sensitive crop.

Iron

In general, the supply of soluble Fe to plants from soil is related to the soil carbonate level, which is important when soil pH is more than 7. If carbonates are present, soil wetness, cold soils, excessive tillage and high soluble-salt levels influence the presence and severity of chlorosis. Most of our crops are not sensitive to low available iron and are adapted to regional conditions. However, iron chlorosis has been seen in flax, field pea and dry bean and is a particularly serious problem
in soybean.

Seed treatment with FeEDDHA provides an early-season green-up, but yield responses have been small. Foliar applications have been inconsistent in increasing yield and multiple applications may be necessary. If treatments are made, they should be conducted early in the crop year. Late treatment of the crop will be much less effective. The best solution on fields where iron chlorosis occurs is to plant varieties that are more resistant to this problem. NDSU rates about 200 soybean varieties each year for chlorosis resistance. The most recent data can be found at www.soilsci.ndsu.nodak.edu/yellowsoybeans  and www.yellowsoybeans.com. 

Manganese

Few documented responses to manganese in North Dakota are available. Therefore, a recommendation is not generally made for any soil test level.

Copper

In a recent study in North Dakota, yield increases due to soil-applied copper were documented; however, the responses were on low organic-matter, loamy sand soils with low (less than 0.3 ppm) copper levels. A number of companion trials on similar soils resulted in no yield increase. At best, copper should be applied only to low organic-matter, sandy soils with low copper levels, but expect a success rate of about
15 percent. Copper is expensive and its use should based on weighing the productivity of responsive soils with low return of benefits if copper were applied.

Fertilization Recommendation Tables for Crops Commonly Grown in North Dakota

The following tables can be used for the yield
potentials shown.

For other yield potentials, use the equations at the bottom of each table.

The abbreviations used in the tables are as follows:

YP = yield potential

STN = soil test nitrogen

STP = soil test phosphorus

STK = soil test potassium

PCC = previous crop credit

 

Table 1. Soil test calibration levels used in North Dakota.

                                                                                                                                                     Categories

Nutrient

Name of Test

Very Low

Low

Medium

High

Very High

                                                                                                 —————————————       ppm extractable     �������������
 

                                                                                                ———————————��      lbs/acre extractable      ————————————Nitrogen (N)                                          H₂O Extract                               Calibration of nitrogen is dependent on yield potential and crop
 

Sulfur (S), lb/a-2 feet	H2O Extract	0-9	10-19	20-29	30-39	40+
Chloride (Cl), lb/a-2 feet****	H2O Extract	0-10	10-20	20-30	30-40	40+

*       This calibration is only for sensitive crops, such as corn, potato, flax and edible beans.
**     This calibration is only for wheat and barley in sandy loam or coarser soils with organic matter less than 2.5 percent.
        Response to copper is not common. Responses have been found only in 15 percent of medium or lower testing locations.
***   Deficiencies of these nutrients have not been confirmed in North Dakota.
**** This calibration is only for small grain.

The amount of nutrient extracted by a particular soil extractant has little meaning or usefulness until it has been calibrated under field conditions. In North Dakota, we use five soil test calibration categories to give meaning to the soil test results.
The categories from very low to very high are defined as follows, unless explained differently above:

• Very Low (VL) In this category, the probability of getting a response to applied nutrient is greater than 80 percent.
• Low (L) Crops growing on fields in this category will respond to applied nutrient 50 percent to 80 percent of the time.
• Medium (M) The probability of getting a response to applied nutrient is 20 percent to 50 percent.
• High (H) In this category, crops will respond to applied nutrient about 10 percent to 20 percent of the time.
• Very High (VH) The probability of getting a response to applied nutrient is less than 10 percent.

 

Table 2. Alfalfa.

     bu/a             lb/acre-2'                                 ——————— lb P₂O₅/acre �������              —————— lb K₂O/acre ———————

2	0		34	24	15	6	0	96	66	35	5	0
4	0		67	49	30	12	0	192	132	71	10	0
5	0		84	61	38	15	0	241	165	89	13	0
6	0		101	73	45	17	0	289	197	106	15	0

Table 3. Barley, feed.

     bu/a             lb/acre-2'                                 ——————— lb P₂O₅/acre �������              —————— lb K₂O/acre ———————

40	70		28	20	12	4	0	45	31	17	3	0
60	100		43	31	19	7	0	67	47	26	5	0
80	135		57	41	25	9	0	89	62	35	7	0
100	170		71	51	31	11	0	112	78	44	8	0

Table 4a. Barley, malting grade, in cooler, moister climates within North Dakota.

       bu/a           lb/acre-2'                                  ——————— lb P₂O₅/acre ———————           ——————— lb K₂O/acre ———————

40	60		28	20	12	4	0	45	31	17	3	0
60	90		43	31	19	7	0	67	47	26	5	0
80	120		57	41	25	9	0	89	62	35	7	0
100	150		71	51	31	11	0	112	78	44	8	0

Table 4b. Barley, malting grade, in warmer, drier climates within North Dakota*.

     bu/a             lb/acre-2'                                 ——————— lb P₂O₅/acre �������              —————— lb K₂O/acre ———————

40	48		28	20	12	4	0	45	31	17	3	0
60	72		43	31	19	7	0	67	47	26	5	0
80	96		57	41	25	9	0	89	62	35	7	0
100	120		71	51	31	11	0	112	78	44	8	0

  * This recommendation is most useful for the North Dakota region from north of Williston south, and everything west of the Missouri River. In years with low soil moisture, growers further east may benefit from this formula (see Figure 1).

Table 5. Buckwheat.

     bu/a             lb/acre-2'                                 ——————— lb P₂O₅/acre �������              —————— lb K₂O/acre ———————

25	55		30	22	13	5	0	41	29	18	6	0
30	65*		36	26	16	6	0	49	35	21	7	0
35	75*		42	30	19	7	0	57	41	25	8	0
40	90*		48	35	21	8	0	65	47	28	9	0

Table 6. Canola.

     bu/a             lb/acre-2'                                 ——————— lb P₂O₅/acre �������              —————— lb K₂O/acre ———————

1000	65		33	24	15	6	0	47	34	20	6	0
1500	100		49	36	23	9	0	71	50	30	10	0
2000	130*		65	48	30	13	0	94	67	40	13	0
2300	150		75	55	35	18	0	108	77	46	15	0
2500	150		82	60	38	16	0	118	84	50	16	0
3000	150		98	72	46	18	0	142	100	60	20	0

Table 7. Clover (Alsike, Red, Birdsfoot Trefoil, grass-legume).

     bu/a             lb/acre-2'                                 ——————— lb P₂O₅/acre �������              —————— lb K₂O/acre ———————

2	0		36	25	13	2	0	87	60	34	7	0
3	0		54	37	20	3	0	130	90	50	11	0
4	0		72	49	27	4	0	173	120	67	14	0
5	0		90	62	34	6	0	217	150	84	18	0

Table 8. Corn, grain and popcorn.

     bu/a             lb/acre-2'                                 ——————— lb P₂O₅/acre �������              —————— lb K₂O/acre ———————

80*	96		51	37	22	8	0	82	58	35	12	0
100	120		63	46	28	11	0	102	73	44	14	0
150	180		95	69	42	16	0	153	109	65	22	0
200	240		127	92	56	21	0	204	146	87	29	0

 Table 9. Corn, silage.

     bu/a             lb/acre-2'                                 ——————— lb P₂O₅/acre �������              —————— lb K₂O/acre ———————

10	105		51	37	23	9	0	83	59	35	11	0
14	145		71	52	32	13	0	116	83	49	15	0
18	185		92	67	41	16	0	149	106	63	20	0
22	230		112	81	50	20	0	183	130	77	24	0

Table 10. Sweet corn.

     bu/a             lb/acre-2'                                 ——————— lb P₂O₅/acre �������              —————— lb K₂O/acre ———————

4	70		40	29	17	6	0	78	57	36	15	0
6	110		60	43	26	9	0	116	85	54	23	0
8	145		80	57	35	12	0	155	114	72	30	0
10	180		100	72	44	16	0	194	142	90	38	0

Table 11. Crambe.

     bu/a             lb/acre-2'                                 ——————— lb P₂O₅/acre �������              —————— lb K₂O/acre ———————

1000	50		33	24	15	6	0	47	34	20	6	0
1500	75		49	36	23	9	0	71	50	30	10	0
2000	100		65	48	30	13	0	94	67	40	13	0
2500	125		82	60	38	16	0	118	84	50	16	0

Table 12. Dry bean (pinto, navy, other).