Plant Nutrients

1. Plant Nutrients

2. Assessment of Nutrient Needs • Visual inspection of crops for deficiency symptoms • Damage could have occurred already • Symptoms may not be reliable • Soil tests to measure nutrient levels • Growers depend on this method to determine lime and fertilizer needs • Tissue testing for nutrients in plants • May uncover problems that soil test misses

3. Soil Testing Soil testing Soil sampling Soil Interpretation Recommendation

4. Take a Good Soil Sample to Help Make Good Decisions

5. Rotation field 2 Rotation field 1 Low Spot Permanent Pasture Taking a Soil Sample Sampling Area Should not exceed 10 acres For row crops Sampling Depth Conventional tillage: 6-9 inches No till: Use special pH sample in top 2” Sod or pasture: 2-3 inches Tree Crops: 18-24 inches

6. Soil Test Results pH: Acid, Neutral, Alkaline Soil Test Rating: VL, L, M, H, VH, EH (How much of a nutrient is available) Soil Test Index: (How high or how low a nutrient is in the soil)

7. Soil Test Explanation Index Soil Test Rating Very Low (H) 0-50 Severe deficiency Low (L) 60-70 Moderate deficiency Medium (M) 80-100 Near optimum: some fertilizer recommended High (H) 110-200 Adequate for most crops Very High (VH) 210-400 Two to four times the amount considered adequate; none should be applied Extremely High (EH) 410+ Excessive; none should be applied Phosphorus, Potassium, Magnesium, calcium

8. Additional Resources (1) Nitrogen Fertilizer Recommendation for Corn in Iowa http://www.agron.iastate.edu/soiltesting/pm1714.pdf http://www.agron.iastate.edu/soiltesting/ (2) Iowa State University Soil Testing Lab www.extension.iastate.edu/store www.agronext.iastate.edu/soilfertility) (3) Extension Publications.

9. Plant Food Elements

10. Nitrogen • Nitrogen is a primary component of proteins and is part of • every living cell. Functions of Nitrogen • Speeds growth • Vigorous growth, large leaves, and long stem internodes. • Required for the formation of dark green pigment: chlorophyll. • Promotes better production of chlorophyll hence it is required • for better source of forage, feed and human nutrition. • Plants use water best when they have ample nitrogen.

11. Excess Nitrogen • Soft growth is more prone to diseases and insects • Overly rapid growth slows maturity and ripening of many • crops • N promotes vegetative rather than reproductive growth • of flowers and leaves. • Over-fertilized tomato plants promote lush growth • but few fruits • Soft, weak easily injured growth • Stems are weaker and more easily to lodge

12. Nitrogen deficiency Slow growth and stunting Plants lack dark green color of well fed plants: Chlorosis

13. Phosphorus Functions • Phosphorus is part of chromosomes and genes and so it is • involved in plant reproduction and cell division. • P spurs early and rapid growth and helps a young plant • develop its roots • P helps plants resist cold and diseases • P speeds up crop maturity • P aids blooming and fruiting • P improves the quality of grains and fruits

14. Phosphorus Deficiency There is stunted growth but plants could remain green. Plants have a purple tint to leaves and stems, starting on lower Older leaves

15. Potassium (Potash) Functions • Activates enzymes needed in the formation of protein, starch • cellulose and lignin. • It is important in the formation of thick cell walls and strong, • rigid plant stems. • Regulates the opening and closing of pores in the leaf through • which water, oxygen and carbon dioxide pass. • Important in the development and ripening of fruits like apples • or tomatoes • Needed for proper growth of root and tuber crops

16. Potassium Deficiencies Seen less often than the other primary nutrients. Shortages occur primarily in sandy heavily leached soils. “Marginal scorch” or burnt edges of lower, older leaves

17. Secondary Nutrients Calcium Functions of Calcium • Required by plants mainly to build cell wall • Crispness of apples come from calcium pectate in the fruit cells • Ca largely controls soil pH and helps in the formation of soil • structure • Calcium plays a role in protein formation and carbohydrate • movement in plants

18. Calcium Deficiencies • Commonly appear in fruits and vegetables. • Apple growers prevent “water core” (collapse of cell walls) in • apples by spraying trees with Ca. • This is similar to “blossom end rot” in tomatoes. • Soil dries out and slows movement of Ca to roots during rapid • root development. • Ca deficiency cause misshapen roots on root vegetables.

19. Magnesium Functions of Magnesium • It is an essential ingredient in chlorophyll formation • Each chlorophyll molecule has one magnesium atom at the center • Magnesium activates a number of important enzyme systems • Mg is involved in protein, carbohydrates and fat synthesis

20. Sulfur Functions of Sulfur • Needed in the formation of proteins and chlorophyll • Aids in the formation of nodules in legumes and seed production • S improves stress tolerance. • Alfalfa, members of the mustard family and members of the onion • family need much sulfur. • The pungent flavors derive from sulfur compounds

21. Sulfur Deficiencies • Stunted growth • Older leaves are pale green – similar to N-deficient plants

22. Micronutrients • These form special organic-metal molecules called Enzymes. • Enzymes activate biological reactions in living systems. • The difference between enough and too much can be quite • narrow, sometimes only a few pounds per acre Please apply elements with caution

23. Effect of pH on nutrient availability

24. Iron Functions of Iron • Iron is part of many enzymes necessary for the formation of • chlorophyll • It is an abundant element in rocks and soils but it is also one • of the most commonly deficient micronutrient

25. Symptoms of Iron Hunger “Chlorosis”: Yellowing of interveinal leaves. Mainly new leaves

26. Manganese Functions of Manganese • Speeds up germination and crop maturity • Helps uptake of several other nutrients • Functions in chlorophyll development

27. Symptoms of Manganese Deficiency • Dwarfing • Chlorosis on new leaves

28. Zinc Functions of Zinc Needed in the metabolism of protein Involved somehow in the production of chlorophyll

29. Symptoms of Zinc Deficiency Fruit crops including peaches and citrus are sensitive to zinc deficiency Field crops also include corn, soybeans, cotton, and potatoes Symptoms include spots on leaves Chlorosis between veins is also common

31. Fertilizers Fertilizer Material Chemical compounds or mixtures containing nutrient • Mixed fertilizer • Weed and Feed fertilizers • Liquid fertilizers • Fertilizer Spikes • Slow-release fertilizers Added to the soil to provide essential nutrients to plants

32. %N % Potash K O 2 % Phosphate (P2 O 5 ) Fertilizer Grade: 13 - 13 - 13

33. Some Popular Fertilizer Grades Available in Alabama Fertilizer Grade % of all Grades sold in Alabama 13 - 13 - 13 49% 8 - 24 - 24 7% 8 - 8 - 8 7% 5 - 10 - 15 7% 7 - 21 - 21 7% 5 - 15 - 30 6% 18 - 46 - 0 (diammonium phosphate) 5% 0 - 20 - 20 4% 3 - 9 - 18 4% 10 - 10 -10 2% 15 - 0 - 15 <18%

34. Examples of Fertilizer Calculations Recommendation: 120 Ib N, 60Ib Phosphate, 60 Ibs potash per acre Fertilizer Grade: 13 - 13 - 13 Before Planting 60/13% percent = 461 pounds / acre of 13 - 13 - 13 Amount needed Analysis of source Size of Garden : 50 x 20 = 1,000 square feet 1 acre = 43, 000 square feet 1,000 square feet = 1,000 / 43,000 = 0.023 acres Fertilizer needed = 0.023 x 461 pounds per acre = 0.6 Ib

35. Examples of Fertilizer Calculations Recommendation: 120 Ib N, 60Ib Phosphate, 60 Ibs potash per acre Fertilizer Grade: 13 - 13 - 13 Sidedressing Use ammonium nitrate (34 - 0 - 0) Amount needed per acre = 60 / 34% = 176 pounds Size of Garden = 0.023 acres Amount required for side dressing = 0.023 x 176 = 4 pounds

36. Recommendation: “Per 50 ft x 20 ft garden apply 6 pounds of 8 - 8 - 8 at planting and sidedress with 4 pounds of 8 - 8 - 8” Fertilizer Grade Available: 13 - 13 - 13 At Planting 6 Ib (expected) x 8 (required) / 13 (available ) = 3.7 Sidedressing 4 x 8 / 13 = 2.5 Ib, 13 - 13 - 13