Family Farm Series Publications:
Vegetable Crop Production

Appendix

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Using Micronutrients

Micronutrient deficiencies have not been commonly reported in California. Furthermore, even if a deficiency is found, some vegetable crops yield little, if any, better when you correct the deficiency. To find out which vegetables are most helped when a deficiency is corrected, see Table 9.

available nutrients in relation to pH
From "Illinois Agronomy Handbook, 1979-1980," University of Illinois Cooperative Extension Service, Circ. 1129.

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Vegetable Response To Micronutrients

Table 9. Here's our best estimate on how vegetables might react to added micronutrients when a deficiency is corrected.
Crop Manganese Boron Copper Zinc Molybdenum Iron
1/low -- little or no response
medium -- intermediate response
high -- highly responsive
Asparagus low low low low low medium
Beans high low low high medium high
Beets high high high medium high high
Broccoli medium medium medium   high high
Cabbage medium medium medium   medium medium
Carrots medium medium medium high low high
Cauliflower medium high medium   high  
Celery medium high medium   low  
Cucumbers medium low medium      
Corn medium low medium high low medium
Lettuce high medium   high    
Onions high low high high high  
Parsnips medium medium medium      
Potatoes high low low medium low  
Radishes high medium medium   medium  
Spinach high medium high   high high
Sweet corn medium low medium high low medium
Tomatoes medium medium medium medium medium medium
Turnips medium high medium   medium  

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Micronutrients - Soil Applied

Table 10. How to apply micronutrients on deficient soils (General guide).

Soil tests (for zinc or boron) will give you a clue on whether your soil is deficient.

ADDING ZINC TO SOIL (General guide)

Amount of element usually applied per acre

Usual source

Usual formulation

Amount of usual formulation per acre:

Broadcast--

Banded--

Application method

How often to apply

ADDING COPPER TO SOIL

Copper chelate is suggested, since other sources may become unavailable on alkaline soils. Foliar sprays may be used. Follow label instructions.

BORON

To prevent soil buildup of boron on sensitive crops that might follow, foliar sprays are often preferred.

IRON

Foliar sprays have normally been more practical on row crops, except perhaps on leafy vegetables. On leafy vegetables, you will need to be very careful not to burn leaves, especially with unproven formulations.

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Micronutrients - Foliar Applied

Table 11. Foliar sprays for deficient crops; General guidelines for usual amounts applied in various states:
Material HOW TO APPLY
Grams of material per gallon of water for small trial *		 Pounds of material per acre ** Comments
* Actual B applied is 0.1 lb for medium responsive crops or 0.3 lb for highly responsive crops.
** The range shown in grams per gallon of test spray is the same range shown in pounds per 100 gal per acre.
Manganese sulfate 18.1 to 27.2 g 4 to 6 Do not apply without testing for leaf burn first.
Zinc sulfate 3.6 to 9.0 g 0.8 to 2 A second spray may be needed in 2 or 3 weeks.Do not apply zinc sulfate without testing for leaf burn first.
Fixed copper or chelated copper or Bordeaux mixture Follow label directions; 1 lb per 100 gal = 4.5 g per 1 gal. Follow label directions. One spray should be enough for deficient crops. Do not apply without testing for leaf burn first.
Solubor ® 2.3 g to 6.8 g 20% material* 0.5 to 1.5 lb of 20% material* Do not apply without testing for leaf burn first.
Iron chelate Follow label directions; 1 lb per 100 gal = 4.5 g per 1 gal. Follow label directions One to 2 sprays. Do not apply without testing for leaf burn first.
Sodium molybdate 0.6 g 2 oz Rarely applied except when deficient on cauliflower, broccoli, onion. Do not apply without testing for leaf burn first.
Calcium nitrate 22.7 g to 68.0 g 5 to 15 Use the 15 pound rate for prevention of blackheart on celery. May be tested on tomatoes where tissue is low in calcium. Do not apply without testing for leaf burn first.
Magnesium sulfate 45.4 g 10 Where used on celery it should be tested with 5 lb calcium nitrate to prevent blackheart. Do not use on crops without testing for leaf burn first.

WARNING: Do not spray crops, especially leafy vegetables, with micronutrients shown in Table 11 unless you first test the spray on several feet of row.

USING TABLE 11 FOR DEFICIENT CROPS

Certain conditions could cause the spray to "burn" the crop. For this reason, grams per gallon of "test spray" are listed.

You should use a simple, inexpensive gram scale for such tests. After you've sprayed several feet of row, check plants in 48 to 72 hours. If you see no injury and the weather holds, you can consider going ahead with larger scale treatments. Such "test sprays" are especially important on leafy vegetables. Here, you don't even want a slight "cosmetic" burn.

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Soil Tests

Here are the pages to show the lab. You don't need to understand the technical terms. Just be sure your lab can run these specific tests (not just any testing method).

  1. Saturation percentage (SP)--grams of water required to saturate 100 grams of soil.
  2. Phosphorus--extraction by 0.5 M, pH 8.5 NaHCO3 solution. Also called Olsen bicarbonate extraction. Water soluble P is used to estimate available P in peat and muck soils. Phosphate may be determined in extracts as the molybdenum blue, using ascorbic acid or SnCl2 as the reducing agent.
  3. Potassium--exchangeable K is measured in ammonium acetate or other suitable extract. Except on celery or potatoes, the boiling nitric acid test is also used if the ammonium or sodium acetate test is below 100-120 ppm K.
  4. Zinc--DTPA extraction.
  5. Boron--expressed as water soluble ppm in the saturation extract.
  6. pH--determined as a soil paste wet to the saturation percentage.
  7. ECe--electrical conductivity of the saturation extract expressed as millimhos per centimeter at 250C.
  8. SAR--Sodium Adsorption Ratio; a calculated value used to estimate exchangeable sodium percentage (ESP) after long-term use of the water.
  9. Calcium--exchangeable Ca. For SAR determination, water soluble Na, CA and Mg are used.
  10. Magnesium--exchangeable Mg. (See also calcium, test 9, above.)
  11. Sulfur--available S is extracted by shaking 10 g of soil with 50 ml 0.1 M LiCl. Sulfate is determined in the filtrate using methods of Johnson and Nishita. This has not been a highly reliable test.

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Conversion Tables

CONVERSION TABLE - POUNDS PER ACRE TO KILOGRAMS PER HECTARE
Pounds per acre
(lb./A.html)		 Kilograms per hectare
(kg/ha)		 Pounds per acre
(lb./A.html)		 Kilograms per hectare
(kg/ha)
Kilograms per hectare pounds per acre x 1.12
Pounds per acre = kilograms per hectare x 0.89
0.25 0.28 350 392
0.33 0.37 400 448
0.5 0.56 450 504
0.75 0.84 500 560
1 1.12 550 616
5 5.6 600 673
10 11.2 700 785
40 44.8 750 841
50 56 800 897
100 112 850 953
150 168 900 1009
200 224 1000 1121
250 280 2000 2242
300 336    
CONVERSION TABLE - APPLYING NITROGEN
Pounds N per acre Kilograms N per hectare Pounds N per acre Kilograms N per hectare
Or kilograms N per acre = pounds N per acre x 1.12
1 1.1 150 168
5 5.6 180 202
10 11.2 200 224
15 16.8 250 280
20 22.4 300 336
30 33.6 350 392
40 44.8 400 448
50 56 500 560
100 112 600 673
CONVERSION TABLE - APPLYING PHOSPHORUS
Pounds P205 per acre
(lb/A)		 Kilograms P205 per hectare
(kg P205/ha)		 Pounds P per acre
(lb P/A)		 Kilograms P per hectare
(kg P/ha)
* Example:, 100 pounds P205 per acre 112 kilograms P205 per hectare
44 pounds P per acre = 49 kilograms P per hectare
Pounds P205 x .44 = pounds P
1 1.1 0.44 49
5 5.6 2.2 2.5
10 11.2 4.4 4.9
15 16.8 6.6 7.4
20 22.4 8.8 9.9
40 44.8 17.6 19.7
50 56 22 24.7
60 67.3 26.4 29.6
* 100 * 112 * 44 * 49
160 179 70 78
200 224 88 99
240 269 106 119
300 336 132 148
340 381 150 168
400 448 176 197
500 560 220 247
600 673 264 296
CONVERSION TABLE APPLYING POTASSIUM
Pounds K20 per acre
(lb/A)		 Kilograms K20 per hectare
(kg K20/ha)		 Pounds K per acre
(lb K/A)		 Kilograms K per hectare
(kg K/ha)
* Example: 100 pounds K20 per acre 112 kilograms K 20 per hectare
83 pounds K per acre = 93 kilograms K per hectare
Pounds K2 x .83 = pounds K
1 1.1 0.83 0.93
5 5.6 4.6 5.2
10 11.2 8.3 9.3
50 56 41.5 46.5
* 100 * 112 * 83 * 93
200 224 166 186
300 336 249 279
400 448 332 372
500 560 415 465

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