Role of micronutrients in agronomic crops. Rich Koenig, Extension Soil Scientist

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1 Role of micronutrients in agronomic crops Rich Koenig, Extension Soil Scientist

2 Acknowledgments Washington/Idaho Green Pea Association $923 in funding given in 2007 for the studies we will describe here ( ) Covered the actual costs associated with soil analysis, travel to and from field, fertilizers, etc. (not labor) Partnership between Oregon State University (Clive and Tom before him), USDA-ARS (Lyndon) and Washington State University

3 Issues and topics Many micronutrients and packages on the market Do you need them? How can you determine which micronutrients are needed? Roles of micronutrients and deficiency symptoms My input on likely deficiencies and approaches

4 Micronutrients (trace elements) Zinc* Iron Copper Manganese Chloride* Molybdenum* Boron* Nickel Cobalt *documented responses in inland northwest dryland field crops

5 Five types of nutrient deficiency symptoms Chlorosis - yellowing due to a reduction in chlorophyll Uniform or interveinal iron, zinc, manganese, molybdenum Necrosis - death of plant tissue manganese, copper Lack of new growth or terminal growth resulting in rosetting boron Anthocyanin accumulation resulting in reddish color (phosphorus) sometimes zinc, boron Stunting with either normal or dark green color or yellowing molybdenum, zinc

6 Required for many enzymes involved in photosynthesis and reproduction of genetic material (DNA) during cell division Deficiency symptoms: stunted plants; little leaf syndrome, yellowing on younger leaves Zinc (Zn)

7 Central role in chlorophyll production, photosynthesis, energy transfer within plant Deficiency symptoms: general yellowing or interveinal chlorosis (green veins, yellow between veins) on younger leaves Iron (Fe)

8 Copper (Cu) Important for energy transfer, photosynthesis, resistance to certain diseases Deficiency symptoms: decreased nodulation and N fixation by legumes, white tip disorder in cereals International Plant Nutrition Institute

9 Important for energy transfer, photosynthesis reactions Deficiency symptoms: greenish-grey spots or flecks on lower leaves; chlorosis Manganese (Mn) International Plant Nutrition Institute

10 Chlorine/chloride (Cl) Roles in disease resistance, stem strength, water relations/drought tolerance Deficiency symptoms: lodging, leaf spot syndrome (more important for cereals than legumes)

11 Important in the activation of enzymes involved in nitrogen fixation by legumes and nitrate reduction in non-legumes Deficiency symptoms: general yellowing, small plants; similar to nitrogen deficiency (more important for legumes than cereals) Molybdenum (Mo)

12 Boron (B) Important in sugar transport, cell wall properties that influence cell growth or expansion Deficiency symptoms: stunted plants, dead or misshapen young leaves, red coloration, sterile flowers, bud and/or fruit drop (more important for legumes than cereals)

13 My input on likely deficiencies and approaches to solving them

14 2005 M-F green pea fertility trial soil test results (1 ft depth) Parameter Soil ph Phosphorus Potassium Sulfur Zinc Boron Iron Manganese Copper Average of 4 samples ppm 360 ppm 3 ppm 1.7 ppm 0.18 ppm 49 ppm 27 ppm 1.5 ppm Interpretation Borderline for peas (>5.5) Adequate for peas (>18) Adequate for peas (>100) Very low for peas (>10) Adequate for peas (>1.0) Very low for peas (>0.5) Adequate for peas (>5) Adequate for peas (>1) Adequate for peas (>0.6)

15 2007 M-F green pea fertility trial soil test results (1 ft depth) no-till site Parameter Soil ph Phosphorus Potassium Sulfur Zinc Boron Iron Manganese Copper Average of 4 samples ppm 492 ppm 4 ppm 1.15 ppm 0.29 ppm 43 ppm 36 ppm 1.3 ppm Interpretation Borderline for peas (>5.5) Adequate for peas (>18) Adequate for peas (>100) Very low for peas (>10) Adequate for peas (>1.0) Very low for peas (>0.5) Adequate for peas (>5) Adequate for peas (>1) Adequate for peas (>0.6)

16 2007 M-F green pea fertility trial soil test results (1 ft depth) conventional site Parameter Soil ph Phosphorus Potassium Sulfur Zinc Boron Iron Manganese Copper Average of 4 samples ppm 422 ppm 5 ppm 0.38 ppm 0.27 ppm 43 ppm 38 ppm 1.5 ppm Interpretation Borderline for peas (>5.5) Adequate for peas (>18) Adequate for peas (>100) Very low for peas (>10) Very low for peas (>1.0) Very low for peas (>0.5) Adequate for peas (>5) Adequate for peas (>1) Adequate for peas (>0.6)

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18 The most likely deficiencies in field crops in this area Zinc Boron Molybdenum? Chloride

19 Approaches to define deficiencies Soil test Tissue test a few fields and look for low or marginal values On-farm tests for micronutrients

20 Reliability of soil or tissue test Nutrient Zinc Iron Copper Manganese Chloride Boron Molybdenum Nickel Cobalt Soil test Good Poor Adequate Good Good Adequate none???? Tissue test Good Poor Good Good Good Good Good????

21 Example: tissue testing (green peas) 50 most recently developed leaflets at first bloom Element Nitrogen Phosphorus Potassium Sulfur Zinc Boron Iron Manganese Molybdenum Copper Source: Plant Analysis Handbook II (1996) Micro-Macro Publishing Sufficiency range 4 to 5% 0.3 to 0.8% 2.0 to 3.5% 0.2 to 0.3% 25 to 400 ppm 5 to 60 ppm 50 to 300 ppm 25 to 400 ppm >0.6 ppm 7 to 100 ppm

22 Tissue testing Interpretation is highly dependent on growth stage and plant part Most labs are equipped to do these tests and interpret the results Contact the lab early to make sure samples are collected at the right time and from the right part of the plant

23 Micronutrient application methods (field crops) Nutrient Zinc Iron Copper Manganese Chloride Boron Molybdenum Nickel Cobalt Soil application Marginal (broadcast) (seed coating)???? Foliar application Marginal (? at flowering) --????

24 Perspectives on boron and molybdenum fertility for legumes in Idaho (Mahler, 2002) High rainfall environments (>20 inches) Low ph (5.7 or below) soils Boron soil test below 0.5 ppm ½ to 1 lb boron/acre broadcast, not banded Molybdenum 1 oz/acre as seed treatment

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