Yields and Fertility for Corn

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1 Corn Starters Soil Fertility vs. Soil Productivity. The need for Starters. The content of Starters. Soil Test Interpretation. Crop Removal. Rotation Removal.

2 Soil Fertility Every conversation regarding soil fertility must start with a summary of soil test results from the field in question. Soil testing is the only definitive way to establish the fertility level of a soil and determine a course of action. A soil test measures the soils ability to supply a given nutrient. High soils means a greater ability to supply that nutrient and a lower response to applied nutrients.

3 Yields and Fertility for Corn We noticed for quite some time that yields tend to be higher in low slope areas of fields. Topography is strongly correlated to yield. Higher yields come from low slope positions high in organic matter, deeper topsoil profile, higher moisture holding capacity relative to up slope positions. Soil Quality makes the difference. In drought stricken fields that average 60 bushels of corn had yields ranging from zero to 185 bushels per acre. (same fertility same rainfall) In flat, level fields soil quality in terms of depth, % organic matter show differences in growth patterns and yield.

4 Soil Fertility vs. Soil Productivity Soil fertility as measured by a proper soil test indicates the soils ability to supply nutrients to a crop. The soil test levels by themselves do not guarantee high yields nor do the results quantify nutrients. Soil test results should be viewed as an indicator of the soils ability to supply nutrients to soil solution. A high test indicates a soil has a great potential to supply a given nutrient and the need for additional nutrients is low. AGRI-FOOD LABORATORIES

5 Soil Fertility vs. Soil Productivity Conversely a low test indicates the need for supplementation, either from manure or fertilizer. Soil testing has value when more than 1 year of testing can be graphed to form a trend line. If you have a high soil test and experience response to fertilizer then you have a productivity issue ( Soil Compaction, fine texture) or you have a highly variable field. Fields with a high spatial variance in soil tests usually need more fertilizer to obtain maximum yield. AGRI-FOOD LABORATORIES

6 Soil Productivity A fertile soil is usually a productive one but not always. Soil productivity and soil fertility are often mingled together. High soil test mean high yields? Some of the lowest yielding areas have the highest soil fertility. Usually these are thin topsoil locations low in organic matter, or poor drainage, no crop removal resulting in high soil test numbers. AGRI-FOOD LABORATORIES

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9 To Achieve the Maximum Level of Aggregate Stability Clay content (%) Organic matter content (%) AGRI-FOOD LABORATORIES

10 Traffic Pattern, wet soil at planting. AGRI-FOOD LABORATORIES

11 Year 2000 examples. % ppm Corn N P K Mg Ca Zn Mn B Good Bad Critical Barley Bad critical Soil test ph 4.8, P 34, K65, Mg 50, Ca 850 ppm Problem is ph, however dead tissue was sent. Looks like a nitrogen and phosphorus problem, dead tissue is high in structural components of calcium compounds. Cell contents are lost. AGRI-FOOD LABORATORIES

12 Managing Soil Fertility What is important is to know where your soil test levels are and in which direction are they heading. Deficient, low, medium, high, very high, excessive. As a rule you cannot farm economically using commercial fertilizer when soil tests are <medium or > than excessive. There are a few exceptions, deep topsoil feet deep allow for greater root massing and more nutrient uptake. These conditions allow better crop growth at a lower nutrient level because roots are drawing nutrients from a larger volume of soil. Big yields, come from big plants and big plants have big roots. Big roots create more massflow, diffusion and root interception of non mobile elements. AGRI-FOOD LABORATORIES

13 Nutrient Credits Because of recent dry years farmers are asking about cutting back on fertilizer due to unused nutrients. Although we can calculate removals and subtract from the application rates this does not lead us to correct assumptions. When crops remove more than you apply soil test levels will drop, and the opposite is also true. What is important is to know your current soil test levels they will indicate whether you can reduce application rates. AGRI-FOOD LABORATORIES

14 Soil Test P and Time 50 Draft P in ppm Standard Deviation +/- 2.8 ppm ppm. Average 40 ppm Years ph, Manure Appl.

15 Soil Test K and Time 250 Soil Test K in ppm Standard Deviation +/- 10 ppm ppm. Average 170 ppm Years

16 Soil Test Interpretation: Index of the Likelihood of Crop Response Soil Test Probability of response to P Category MN-SD SD-ND ON Very low > 80% Low 60-80% 75% Medium 40-60% 55% High 20-40% 25% Very high < 20% < 25%

17 Likelihood of corn yield response to each nutrient increases as the soil test level declines. Odds of Yield Response to Added Soil Test Level P K low 70% 75% medium 55% 50% high 25% 50% very high 25% 30% Based on response summaries in the Ontario Soil Fertility Database project, TFIO

18 Ontario Soil Test P Calibration 100% Relative yield 90% 80% 70% 60% low medium high very high Soil test P (ppm Olsen)

19 Ontario Soil Test K Calibration 100% Relative yield 95% 90% 85% 80% 75% Soil test K (ppm)

20 Starter Fertilizers After understanding soil test levels we need to look at research data from Ontario to determine response and timing of applications. Especially in reduced tillage environments. Stratification of P and K has been one area of study.

21 Starters vs Pop up Starter fertilizers are placed 2 x2 inches in a band below and to the side of the seed. Pop up is low rate on the seed with N plus K not greater than 7 lbs to avoid salt injury. (5 gallons.) Combinations are used by some growers.

22 Starter Content Most starters are a blend of N, P, K with or without micronutrients. Most research shows a benefit in reduced till to pounds of N at planting time. In addition spring applications of N,P,K are out yielding fall applications of P and K with only N in the spring.

23 Fertilizer Placement!

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25 Fertilizer Banding during Fall Strip Tillage Operation

26 Fall

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28 Chisel - Fall PK, Planter N Chisel - No Fall, Planter NPK NT - Fall PK, Planter N NT - No Fall, Planter NPK ZT - Fall PK, Planter N ZT - No Fall, Planter NPK Strip Tillage Trial Tillage and Fertilizer Placement, Shirlimar Farms Corn Yield (bu/ac)

29 Eastep Strip Tillage Alma, 2002 Plow/No Fall PK /Spring NPK 153 Plow/Fall PK/Spring N Only 140 No Till/No Fall PK/Spring NPK 148 No Till/Fall PK/Spring N Only 138 ZT/No Fall PK/Spring NPK 148 ZT/Fall PK /Spring N Only Fall Spring Corn Yield (bu/ac)

30 Corn Yield Response to fall and spring applied K in 3 tillage systems at Kirkton K rate ( lbs K2O) No Till Zone Till Moldboard Spring banded Fall applied O

31 Starter Yields and Economics In the same field of varying soil types Brookston clay to Fox sandy loam we observed the following starter responses. Yield and yield response to starter (BPA.) clay sandy loam Starter No starter Response 11 2 Soil test was 37ppm 43 ppm Soil structure and root massing and soil test level.

32 NMP and Fertility In the NMan software P and K can be applied to maintain soil test levels. Even though soil test may be high some growers opt not to allow soil test values to drop. Starters are a way to apply relatively reasonable rates and provide a yield advantage. The entire crop rotation needs to be understood in order to maintain soil test levels.

33 Crop Removal A 3 year crop removal of Corn, Soybeans, Winter wheat. Crop Yield N P2O5 K2O Corn Soybeans Wheat Total After 3 years the total P and K are 137 and 220 if you did not replace these nutrients, soil test could drop 4 ppm of P and 12 ppm of K.

34 Crop Removal A 3 year crop removal of Corn Silage and 2 years of alfalfa Crop Yield N P2O5 K2O Corn Silage 8 dm Alfalfa Alfalfa Total After 3 years the total P and K are 200 and 820 if you did not replace these nutrients, soil test could drop 6 ppm of P and 41 ppm of K.

35 Summary Starters do provide a yield response in most years. Reduced tillage options make fertilizer placement and timing more critical. Starters can provide an opportunity to apply some of the removal requirements. They are an excellent means to apply micronutrients. Acidifying affects of starter bands make micronutrients more available.