Corn/Soybean Efficient Fertility Management. Robert Mullen Nutrient Management/Soil Fertility Specialist Ohio State University January 14, 2008

Transcription

1 Corn/Soybean Efficient Fertility Management Robert Mullen Nutrient Management/Soil Fertility Specialist Ohio State University January 14, 2008

2 Overview Soil test, soil test, soil test! Making recommendations from analysis Nitrogen management Economic based recommendations 1/15/2008 Shelby Co. 2

3 Soil Analysis and Interpretation What to look at! Soil ph (do we need to lime or not?) 1/15/2008 Shelby Co. 3

4 Soil Analysis and Interpretation If soil ph is near optimal range do not lime If it is not, look at buffer ph to determine how much lime to apply 1/15/2008 Shelby Co. 4

5 Soil Analysis and Interpretation Soil test P Is it below the established critical value 1/15/2008 Shelby Co. 5

6 Soil Analysis and Interpretation Soil test K (and CEC) Is soil test K level below the critical value? 1/15/2008 Shelby Co. 6

7 Soil Analysis and Interpretation What about the other information? For the most part will not be used (there are exceptions) 1/15/2008 Shelby Co. 7

8 Generating Recommendations Soil ph, buffer ph, and lime Know the crop species you are going (each species has different tolerance level of soil ph) Assume we a going to corn Example 1 We do not need to lime 1/15/2008 Shelby Co. 8

9 Generating Recommendations Example 2 Soil ph of 5.5 Need lime Now look at buffer ph (buffer ph = lime test index/10) Buffer ph determines lime requirement 1/15/2008 Shelby Co. 9

10 Generating Recommendations Desired ph levels Mineral soils Organic soils Buffer ph Soil ph tons 2000 ENP lime/acre tons/acre /15/2008 Shelby Co. 10

11 Generating Recommendations For this field we need 5.2 tons of lime/acre Remember though not all lime is the same Pay attention to ENP (effective neutralizing power, lb/ton) of liming material Requirement from previous slide is based upon 2000 ENP liming material 1/15/2008 Shelby Co. 11

12 Generating Recommendations If we are purchasing a liming material with an ENP value of 1500 Lime recommendation = lime requirement (value from table) * (2000/ENP of material) For this instance: 5.2 * (2000/1500) = 6.9 tons of liming material per acre! 1/15/2008 Shelby Co. 12

13 Generating Recommendations Look at soil test P level next Field 3 NPA 14 ppm (28 lb/acre) What is critical value from Tri-State Fertilizer Guide 1/15/2008 Shelby Co. 13

14 Generating Recommendations Critical levels for soil test phosphorus K at CEC Crop P ppm (lb/acre) ppm (lb/acre) Corn 15 (30) 88 (175) 100 (200) (200) (250) Soybean 15 (30) 88 (175) 100 (200) 125 (250) 150 (200) Wheat 25 (50) 88 (175) 100 (200) 125 (250) 150 (200) 1/15/2008 Shelby Co. 14

15 Generating Recommendations A little bit low 28 lb/acre (STP) and 30 lb/acre (critical value) We need to apply some P Application rate is given in pounds P 2 O 5 per acre Soil test Yield potential, bu/acre ppm (lb/acre) lb P 2 O 5 /acre (10) (20) (30-60) (70) (80) /15/2008 Shelby Co. 15

16 Generating Recommendations Build-up, maintenance, and drawdown concept (this applies to potassium as well) P 2 O 5 recommendation, lbs/a Critical Level (Corn = 15 ppm) Build Up Maintenance Draw Down SOIL TEST P, ppm 1/15/2008 Shelby Co. 16

17 Generating Recommendations Build-up Designed to increase soil test value to critical level in 4 years Over-application of 1 lb of P 2 O 5 will not increase soil test by one unit Maintenance Designed to maintain soil test level Draw-down Designed to draw-down soil test level 1/15/2008 Shelby Co. 17

18 Generating Recommendations Relationship between applied/removed P and soil test level Generically, for every 6-18 lb of P 2 O 5 applied or removed soil test will change by 1 ppm Available P Precipitated and sorbed P clay soil /15/2008 Shelby Co. 18

19 Generating Recommendations For our example, soil test was 28 lb/acre which is below critical level for P Recommendation is between 35 and 60 lbs of P 2 O 5 per acre If fertilizing a rotation (say corn and beans), you will want to apply a little more P 2 O 5 to satisfy both crops (include crop removal of subsequent crop) 1/15/2008 Shelby Co. 19

20 Generating Recommendations Example 2 Soil test level is 100 lb P/acre Well above critical value WE DO NOT NEED TO SUPPLY P!!! 1/15/2008 Shelby Co. 20

21 Generating Recommendations Evaluate soil test K level Example 1 Soil test level of 85 ppm (170 lb/acre) CEC of 11.0 meq/100g What is the critical value? 1/15/2008 Shelby Co. 21

22 Generating Recommendations Critical levels for soil test K K at CEC Crop P ppm (lb/acre) ppm (lb/acre) Corn 15 (30) 88 (175) 100 (200) 125 (250) 150 (200) Soybean 15 (30) 88 (175) 100 (200) 125 (250) 150 (200) Wheat 25 (50) 88 (175) 100 (200) 125 (250) 150 (200) 1/15/2008 Shelby Co. 22

23 Generating Recommendations Soil test Soil test level is low 85 ppm compared to critical value of 100 ppm Yield potential, bu/acre ppm (lb/acre) lb K 2 O/acre (50) (100) (150) ( ) (280) (300) For soil with a CEC of 10 1/15/2008 Shelby Co. 23

24 Generating Recommendations Example 1 Need to supply between 60 and 95 lb K 2 O per acre for corn crop If fertilizing a rotation, probably need to add more (subsequent crop removal) Like P, over-application of 1 pound of K 2 O does raise soil test level 1 unit More like 2-6 pounds of K 2 O have to be removed or added to change soil test level by 1 ppm 1/15/2008 Shelby Co. 24

25 Generating Recommendations Example 2 Soil test K level 400 lb/acre CEC of 24 Above critical value DO NOT NEED TO SUPPLY K! 1/15/2008 Shelby Co. 25

26 Generating Recommendations May be necessary to consider crop removal Crop Unit of yield Nutrient removed per unit of yield Corn Wheat P 2 O 5 K 2 O lb per unit Grain Bushel Silage Ton Soybeans Bushel Grain Bushel Straw Bushel Alfalfa Ton /15/2008 Shelby Co. 26

27 Summary Know what to look at Pay attention to units and critical levels Use the Tri-State Recommendations as a guide 1/15/2008 Shelby Co. 27

28 Nitrogen Management Ohio State has moved to an economic-based nitrogen recommendation Available online at 1/15/2008 Shelby Co. 28

29 Nitrogen Management Corn after soybeans, N rate, lb/acre y = x R 2 = Maximum Yield, bu/acre 1/15/2008 Shelby Co. 29

30 Nitrogen Management Corn after soybeans, EONR, lb/acre y = x R 2 = EONR, bu/acre 1/15/2008 Shelby Co. 30

31 Nitrogen Management Corn after corn, N rate, lb/acre y = x R 2 = Maximum Yield, bu/acre 1/15/2008 Shelby Co. 31

32 Nitrogen Management Corn after corn, EONR, lb/acre y = x R 2 = EONR, bu/acre 1/15/2008 Shelby Co. 32

33 Nitrogen Management 1/15/2008 Shelby Co. 33

34 Additional Tools PSNT (Presidedress Soil Nitrate Test) Only recommended for fields that have a history of manure or fields that recently had forage legume crops Collect as late as possible (late May at earliest) Collect to a depth of 1 foot (at least 15 cores/20 acres) Nitrate levels above 30 ppm, unlikely to respond to additional N 1/15/2008 Shelby Co. 34

35 Micronutrients Only apply when a deficiency exists Or if a known deficiency has been encountered before Foliar application is a possibility for micros For foliar application, you do not necessarily need a chelated form (unless tank mixing Mn with glyphosate) 1/15/2008 Shelby Co. 35

36 Additional Information 1/15/2008 Shelby Co. 36

37 Illinois Soil Nitrogen Test Let s start with organic matter The general idea is that higher levels of soil organic matter should result in increased N mineralization (at least greater potential) Research revealed this is not necessarily true Okay, is there a specific fraction of organic matter that can be measured Will it provide more information 1/15/2008 Shelby Co. 37

38 Illinois Soil Nitrogen Test The proposed fraction of organic matter evaluated was amino-sugar N Amino-sugar N considered easily mineralized N fraction of organic matter Correlated amino-sugar N concentration to crop response Soil sample collected in the spring 1/15/2008 Shelby Co. 38

39 Illinois Soil Nitrogen Test Correlation Mulvaney et al., 2001 Mulvaney, R.L., S.A. Khan, R.G. Hoeft, H.M. Brown A soil organic fraction that reduces the need for nitrogen fertilization. Soil Sci. Soc. Am. J. 65: /15/2008 Shelby Co. 39

40 Illinois Soil Nitrogen Test Amino-sugar N concentrations below 200 mg/kg were considered responsive Amino-sugar N concentrations above 250 mg/kg were considered nonresponsive It has never been calibrated Its only use was to determine whether or not to apply N Not how much 1/15/2008 Shelby Co. 40

41 Illinois Soil Nitrogen Test Lab method was extremely involved Costly and time consuming So they developed a quicker method 1/15/2008 Shelby Co. 41

42 Illinois Soil Nitrogen Test Correlation with new procedure Khan et al., 2001) Khan, S.A., R.L. Mulvaney, and R.G. Hoeft A simple soil test for detecting sites that are nonresponsive to nitrogen fertilization. Soil Sci. Soc. Am. J. 65: /15/2008 Shelby Co. 42

43 Illinois Soil Nitrogen Test Identified new critical value of: Less than 225 mg/kg responsive More than 235 mg/kg non-reponsive Still not calibrated At this point it looks promising! 1/15/2008 Shelby Co. 43

44 ISNT Other States Wisconsin (Bundy and Labowski, 2004) 1/15/2008 Shelby Co. 44

45 ISNT Other States Data from Iowa (Sawyer and Tabatabai, 2005) 1/15/2008 Shelby Co. 45

46 ISNT Other States Data from Iowa (Sawyer and Tabatabai, 2005) 1/15/2008 Shelby Co. 46

47 Illinois Soil Nitrogen Test Not currently recommended Potential is there (slim at this point) 1/15/2008 Shelby Co. 47

48 Gypsum Different concepts for calcium (bases) in soil Critical level concept Similar to P and K, we just have to have enough in the soil to ensure it is not limiting Basic cation saturation ratio concept Bases in soil solution should be present at an optimum ratio 60-80% Ca, 10-20% Mg, and 2-5% K This will supposedly improve crop production, soil water holding capacity, decrease surface crusting, decrease the potential for erosion, etc. 1/15/2008 Shelby Co. 48

49 Gypsum First off, what is a basic cation A positively charged ionic species Calcium, magnesium, and potassium (and sodium) We can calculate how much of each basic cation occupies the soil exchange sites 1/15/2008 Shelby Co. 49

50 Gypsum Soil calcium Natural level in soil is a function of parent material and weathering Soils in Western Ohio contain between 2500 and 5000 lb of exchangeable Ca per acre 50-80% of the exchange sites These values do vary 1/15/2008 Shelby Co. 50

51 Gypsum Soil calcium Calcium deficiencies are extremely rare Typically induced by acid soil conditions Can we have too much calcium? Not really, but excessive levels of Ca can induce Mg deficiencies Ca 2+ K + Ca 2+ Ca 2+ Mg 2+ 1/15/2008 Shelby Co. 51

52 Gypsum Soil magnesium Like calcium function of parent material and soil weathering Typically occupies 10-30% of the soil exchange sites Deficiencies can and do occur (occasionally) Induced by acid soil conditions Excessive calcium fertilization Can we have too much Mg? Not natively (not in this region anyway) 1/15/2008 Shelby Co. 52

53 Gypsum Is there an optimum ratio between Ca and Mg? Agronomic benefits (scientific data) Any documented yield improvements? 1/15/2008 Shelby Co. 53

54 Gypsum Ohio study late 70s (McLean et al., 1983) Ranges in BCSR Ratio Yield Level Corn (75) Corn (76) Soybeans (77) Soybeans (78) Ca:Mg Highest Five Ca:Mg Lowest Five Mg:K Highest Five Mg:K Lowest Five /15/2008 Shelby Co. 54

55 Gypsum No relationship between basic cation saturation ratio and crop yield Optimum ratio not identified Maintaining an optimum ratio did not result in increased yield 1/15/2008 Shelby Co. 55

56 Gypsum Study on alfalfa (Simson et al., 1979) Wisconsin More optimum ratios did not result in higher yields Ca:Mg Ratio Ca (%) Mg (%) Theresa silt loam: Exchange Sites Saturated With Plainfield loamy sand: Yield (ton/acre) /15/2008 Shelby Co. 56

57 Gypsum Impact of calcium:magnesium ratios on soil conditions Clay flocculation (formation of soil aggregates) % Transmittance Blount Catlin Fayette Miami % Mg saturation Dontsova and Norton, /15/2008 Shelby Co. 57

58 Gypsum It did influence flocculation, but it was soil specific Higher Mg saturated soils did form aggregates slower For soils in this region, typical Mg saturation does not exceed 25-30% Mg saturated soils (>50-60%) are rare in Ohio (at least naturally) Can be found along the West Coast 1/15/2008 Shelby Co. 58

59 Gypsum Impact of soil Ca on water infiltration Dontsova and Norton, /15/2008 Shelby Co. 59

60 Gypsum Comparison of Ca-saturated soil and Mg-saturated soil Remember this would be difficult to find in this region That being said it appears to be soil specific (even if the soil is saturated with Mg) 1/15/2008 Shelby Co. 60

61 Gypsum Impact of gypsum application on erosion Dontsova and Norton, /15/2008 Shelby Co. 61

62 Gypsum Again, this is a comparison between a Ca-saturated soil and a Mgsaturated soil Good luck finding this in Ohio It too appears to be soil specific Not all soils show the benefit (even when Mg-saturated) 1/15/2008 Shelby Co. 62

63 Gypsum Impact on soil crusting Can application of gypsum help with surface sealing? This may be where gypsum warrants merit, but the answer is still out at this time (based on research results) Soil must be dispersive (high amount of dispersible clays) 1/15/2008 Shelby Co. 63

64 Gypsum Can application of gypsum raise soil ph? Yes, but only under specific soil conditions High aluminum concentration in soil solution Very low soil ph (5.0 or less) Both of these conditions have to be met Otherwise, gypsum is not a liming material! 1/15/2008 Shelby Co. 64

65 Gypsum Summary Research to date does not provide enough evidence to show benefit Research is comparing unrealistic soil conditions (Ca-saturated compared to Mg-saturated) There may be benefit but it is isolated to certain types of soils (not sure which soils) Remember it is not a liming material! 1/15/2008 Shelby Co. 65

66 Question 1 When do you need phosphorus in your corn starter fertilizer? Often asked question (especially these days) Simple answer when your soil test P level is below the critical value and you did not want to buy bulk DAP or MAP next question 1/15/2008 Shelby Co. 66

67 Question 1 Starter Phosphorus Most of the benefit from starters is really observed from the nitrogen more so than the phosphorus (under most conditions) 1/15/2008 Shelby Co. 67

68 Question 1 Lentz (1999) 195 Check LTP HTP LDAP LU LAS HDAP HU HAS 190 Grain yield, bu/ac Following Soybean Following Wheat 1/15/2008 Shelby Co. 68

69 Question 1 Lentz (2000) 190 Check LTP HTP LDAP LU LAS HDAP HU HAS 185 Grain yield, bu/a Following Soybean Following Wheat 1/15/2008 Shelby Co. 69

70 Question 1 Most benefit from starter is from nitrogen (especially in mod/high P testing soils) Phosphorus benefits can be found on Soils with low soil test P No-till soils Combinations of above are most likely to benefit from starter P 1/15/2008 Shelby Co. 70

71 Question 2 What element is most needed in the corn starter for soils above the P & K maintenance level? See previous slides By far it is nitrogen 1/15/2008 Shelby Co. 71

72 Question 2 As discussed with Question 1, the majority of the time the real benefit from starter is due to nitrogen This can become an issue when dealing with pop-up (in-furrow) starter fertilizers because you do not have the ability to supply much in the way of fertilizer material 1/15/2008 Shelby Co. 72

73 Question 3 Will the addition of Zn or S increase corn yield enough to cover costs? My suspicion is this revolves around the starter question Let s split this up into two different issues Probability of Zn response Probability of S response 1/15/2008 Shelby Co. 73

74 Question 3 Zn response Where is greatest likelihood of benefit? Soils with high ph (>7.5) Low organic matter levels (<2.0%) Where a Zn deficiency has been noted before Any work with micronutrient packages in starter? 1/15/2008 Shelby Co. 74

75 Question 3 Fertilizer material Research at NWARS, 2006 Rate, gal/acre Placement Plant V5, cm Yield, bu/acre None x ACA oz/acre -ACA agricultural crop additive ( Zn) 2x /15/2008 Shelby Co. 75

76 Question 3 Research at WARS, 2005 Pop-up material Plant height 41 DAP, in Yield, bu/acre None 10.8 a 101 a b 122 b Zn 12.5 b 108 ab b 116 ab b 113 ab -means followed by different letters are significantly different at a probability level of 0.1 1/15/2008 Shelby Co. 76

77 Question 3 S response May be on the rise due to decreased atmospheric deposition from rainfall Where is likely greatest benefit? Low organic matter soils (<2.0%) that are also coarse textured Cool, wet soils in the spring (affect mineralization of S from organic matter) 1/15/2008 Shelby Co. 77

78 Question 3 Research in Ohio Wayne Co Treatment S application rate, lb/acre Yield, bu/acre Control 0 40 a V-FGD b ab P-FGD ab Gypsum ab b -means with different letters are significantly different at the 0.1 probability level 1/15/2008 Shelby Co. 78

79 Question 3 Research in Ohio Clark Co Treatment S application rate, lb/acre Yield, bu/acre Control 0 50 a V-FGD 5 51 a a Gypsum 5 50 a a -means with different letters are significantly different at the 0.1 probability level 1/15/2008 Shelby Co. 79

80 Question 3 Data from MSU reveals that of a recent on-station and on-farm research study, only 1 out of 11 sites showed a response to starter sulfur At this point I would not still recommend S statewide Still isolated to low organic matter, coarse textured soils 1/15/2008 Shelby Co. 80

81 Question 4 What does the critical soil test level mean to me if I have a P level of 35 lb/acre? Since I assuming we are talking corn and soybeans, it means you have enough P in the surface 8 inches to maximize corn growth, but you do not have a lot of wiggle room 1/15/2008 Shelby Co. 81

82 Question 4 Should you apply additional P? If you are fertilizing a two-year rotation, I would recommend it Should you apply more P than just crop removal? No Follow Tri-State Recs 1/15/2008 Shelby Co. 82

83 Question 5 Is broadcast application of P & K an acceptable way to fertilizer corn and/or soybeans? Absolutely Everyone is jumping on the placement bandwagon at this point due to high prices, but is deep placement better than broadcast (in minimum till systems)? 1/15/2008 Shelby Co. 83

84 Question 5 P and K placement may be especially important in minimum or no-till production systems Due to nutrient stratification 1/15/2008 Shelby Co. 84

85 Question 5 Vyn et al., Purdue University 1/15/2008 Shelby Co. 85

86 Question 5 Bordoli and Mallarino, Iowa State University, Agronomy Journal 1998 No response to P placement, broadcast was just as effective as banded Out of 26 sites, 3 showed significant yield increases with deep band placement of K compared to broadcast for corn 1/15/2008 Shelby Co. 86

87 Question 5 Borges and Mallarino, Iowa State University Agronomy Journal 2000 Of 31 sites, 5 showed significant yield increases with deep band placement of P compared to broadcast for soybeans Of 31 sites, 4 showed significant yield increases with deep band placement of K compared to broadcast for soybeans 1/15/2008 Shelby Co. 87

88 Question 5 Deep banding of K specifically may be advantageous in stratified soils, dry summers, and in high yield situations At this point, broadcast fertilizer applications appear as productive as deep-banded in most cases 1/15/2008 Shelby Co. 88

89 Question 6 Can I fertilizer for 2 years (P & K)? Absolutely P & K fertilization is a bit like making an investment Whatever you do not capitalize on in the short term does have a benefit longterm 1/15/2008 Shelby Co. 89

90 Question 6 There are many different possible scenarios Scenarios Excessively high soil test levels (>60 ppm) No real benefit to P & K fertilization Live on the interest for a while High soil test levels (>30 ppm) No short-term benefit to fertilization You can live on the interest but not for very long Maintenance approach 1/15/2008 Shelby Co. 90

91 Question 6 Scenarios Medium soil testing levels (near critical level) (>15 ppm) Fertilization will build soil test Short-term and long-term benefits Low soil testing levels (<15 ppm) Fertilization will build soil P levels and likely provide immediate returns 1/15/2008 Shelby Co. 91

92 Question 6 When fertilizing a rotation, make some educated guesses about how much P & K will be removed from the soil (average yields over last several years) Remember on low testing soils, additional P & K will be necessary to satisfy crop demand We are conducting research on this concept right now 1/15/2008 Shelby Co. 92

93 Question 7 Will cover crops planted after wheat (red clover, annual with manure) provide adequate nitrogen for my corn crop? Short answer unlikely You still require additional nitrogen for maximum economic and agronomic productivity 1/15/2008 Shelby Co. 93

94 Rotational versus Nitrogen Benefit Fallow CC Yield, bu/acre Fallow: Optimum N 162 Max yield 163 Cover Crop: Optimum N 162 Max yield N rate, lb/acre 1/15/2008 Shelby Co. 94

95 Rotational versus Nitrogen Benefit Fallow CC Yield, bu/acre Fallow: Optimum N 162 Max yield 163 Cover Crop: Optimum N 138 Max yield N rate, lb/acre 1/15/2008 Shelby Co. 95

96 Rotational and Nitrogen Benefit Fallow CC Yield, bu/acre Fallow: Optimum N 162 Max yield 163 Cover Crop: Optimum N 141 Max yield N rate, lb/acre 1/15/2008 Shelby Co. 96

97 Rotational or Nitrogen Benefit Differentiating between the type of benefit can only be done with a properly designed experiment The absence of N rates is not an appropriate methodology 1/15/2008 Shelby Co. 97

98 Northwest Research Station In the spring of 2006 we interseeded wheat with red clover at a seeding rate of 10 lbs/acre We established a good clover stand (unlike the previous year) and allowed it to grow until late fall 1/15/2008 Shelby Co. 98

99 Northwest Research Station In late fall (late October/early November), we either incorporated the clover with tillage or we killed it with glyphosate Unfortunately, we did not measure clover biomass, but we did have a nice, relatively uniform clover stand 1/15/2008 Shelby Co. 99

100 Northwest Research Station In the spring, corn was planted in late April with 30 pounds of starter (no starter on the 0 N checks) Corn was sidedressed with UAN to reach total N rates of 80 and 160 pounds per acre 1/15/2008 Shelby Co. 100

101 Soil Nitrate Levels Presidedress soil nitrate test levels as affected by cover crop Cover crop Nitrate level (ppm) No cover 7.25 Clover no-till 7.75 Clover till 7.75 Cover crop did not affect PSNT (measured in early June) 1/15/2008 Shelby Co. 101

102 Corn Yields Main effect of cover crop on corn yield Cover crop No cover Clover no-till Clover till Corn yield (bu/acre) 98 a 116 b 124 c -means followed by different letters are statistical significant at the 0.05 probability level Cover crop did affect corn productivity 1/15/2008 Shelby Co. 102

103 Corn Yields Main effect of nitrogen rate on corn yield N rate (lb/acre) Corn yield (bu/acre) 0 72 a b c -means followed by different letters are statistical significant at the 0.05 probability level Corn was responsive to N 1/15/2008 Shelby Co. 103

104 Rotational or Nitrogen Benefit Was it a nitrogen benefit or a rotational effect? 160 NC RCNT RCT Corn yield, bu/acre Optimum N rate NC 130 RCNT 138 RCT N rate, lb/acre 1/15/2008 Shelby Co. 104

105 Summary of NWARS Data Clearly it was a rotational effect that improved corn yield, not a nitrogen benefit Yield improvement was 18 bu/acre, with today s corn price the establishment cost of the clover would have been covered 1/15/2008 Shelby Co. 105

106 Western Research Station Red clover was drilled after wheat harvest (mid-july) Clover was allowed to grow all winter and the stand was terminated in the spring with tillage or glyphosate in late April Corn was planted in early May Corn was sidedressed in late May 1/15/2008 Shelby Co. 106

107 Soil Nitrate Levels Presidedress soil nitrate test levels as affected by cover crop Cover crop Nitrate level (ppm) No cover 21.1 Clover no-till 20.3 Clover till 15.5 Cover crop did not affect PSNT (measured in early June) 1/15/2008 Shelby Co. 107

108 Corn Yields Main effect of cover crop on corn yield Cover crop No cover Clover no-till Clover till Corn yield (bu/acre) 178 ab 187 a 153 b -means followed by different letters are statistical significant at the 0.1 probability level Cover crop did affect corn productivity 1/15/2008 Shelby Co. 108

109 Corn Yields Main effect of nitrogen rate on corn yield N rate (lb/acre) Corn yield (bu/acre) a a c -means followed by different letters are statistical significant at the 0.05 probability level Corn was responsive to N 1/15/2008 Shelby Co. 109

110 Rotational or Nitrogen Benefit Was there a nitrogen benefit or a rotational effect? 250 NC RCNT RCT Corn yield, bu/acre N rate, lb/acre 1/15/2008 Shelby Co. 110

111 Summary Cover crop did not affect corn yield compared to the no cover treatment Neither a rotational effect or N benefit could be identified There was tremendous variability in this study that did affect our ability to pick out differences 1/15/2008 Shelby Co. 111

112 Western Research Station-Watters Three different cover crops after wheat (field pea, annual ryegrass, and soybean) Field pea was planted on two dates August 23 and September 26 Annual ryegrass was planted on September 26 Soybean was planted on August 23 1/15/2008 Shelby Co. 112

113 Western Research Station-Watters Cover crops were terminated in the spring with herbicide Three N rates 0, 75, and 150 lb N/acre 1/15/2008 Shelby Co. 113

114 Corn Yields Simple effects of cover crop and N rate on corn yield * * Corn yield, bu/acre * * NC FP-Aug FP-Sept ARG Soybean N rate, lb/acre 1/15/2008 Shelby Co. 114

115 Rotational or Nitrogen Benefit? Difficult to tell because crop was still responding to N application Only significant difference was with field pea planted in September It yielded significantly higher than the no cover treatment across all N rates Annual ryegrass at the highest N rate was also higher yielding than the no cover treatment 1/15/2008 Shelby Co. 115

116 Question 8 Can I trust new nitrogen recommendations if so why? Yes, because they are based on data collected right here in Ohio and I say so 1/15/2008 Shelby Co. 116

117 Question 8 On-farm findings the last two years Corn after soybeans 1/15/2008 Shelby Co. 117

118 On-Farm Results-2006 Location Cooperator Agron. Opt. Econ. Opt lb/acre----- Shelby Co. Joslin Van Wert Co. Farm Focus Putnam Co. Ricker Morrow Co. Weiler Molly Caren FSR Pickaway Co. Dresbach Lucas Co. Heilmann Ross Co. McIlvane Paulding Co Lorain Co. Deidrick Madison Co. Stewart /15/2008 Shelby Co. 118

119 On-Farm Results-2006 Corn after corn/wheat Location Cooperator Agron. Opt. Econ. Opt lb/acre----- Van Wert Co. Lichtensteiger Fulton Co. Snyder Fulton Co. Snyder Henry Co. Leaders Lucas Co. Heilmann Fulton Co. Onweller Wood Co. Eckel /15/2008 Shelby Co. 119

120 Questions? Thanks!!!!!! Useful webpages Agronomic Crops Team OSU Fertility web page Crop Observation and Recommendation Network (CORN) 1/15/2008 Shelby Co. 120