Soils and plant nutrients

1. Soils and plant nutrients • Soils and soil texture • Soil texture triangle • Plant nutrients • Major nutrients • Secondary nutrients • Minor nutrients • _________ Exchange Capacity (CEC) • Soil pH

2. Soils • Consists of a series of layers called _________ • Topsoil (A horizon) – upper most layer • Soils consists of: • Mineral particles – determine soil texture • Organic matter • Air and ___________ • Soil organisms

3. Soil texture - Introduction • Soil texture – coarseness or fineness of soil • Why is soil texture important? • It determines: • ____________________ size • Pore space • Amount of air (oxygen) • _________________ flow through soil • How easily the soil is worked • _________________ = easily worked soil • Three soil textures (sand, silt, clay)

4. Sand texture • Largest particles • Size from 0.2mm (finest sand) to 2 mm (coarsest sand) • Warms up and dries early in the spring • Does not hold water or ________________ • Feels gritty if rubbed between fingers

5. Silt texture • Intermediate particle size • 0.002 to 0.05 mm • Often referred to as rock _____________ • Can be transported long distances in water or air • Feels silky or floury to the touch

6. Clay texture • Smallest particle size • < 0.002 mm in size • Does not drain well • Slow to warm up • Difficult to work (not _______________) • ____________ growth poor due to small spaces between particles • Retains nutrients • Feels sticky to touch and forms a ribbon

7. Soil type • Most soils are a mixture of different soil textures • Often a soil type will be dominated by a particular soil texture • Example: ________________ sand • Important to know the soil type because it will determine the ____________________ practices you need to use • What is the drainage? • Do soil amendments need to be added?

8. Soil texture triangle • Allows you to know the soil type of your garden’s soil • Three axis - % clay, % ______, % sand • Example: 20% clay, 40% silt, and 40% sand is a loam soil

9. Nutrients needed by plants

10. Nutrients needed by plants • Can divide the nutrients needed by plants into 3 categories • Major plant nutrients • Nutrients needed in largest amounts • ____________________ plant nutrients • Nutrients needed in moderate amounts • Minor nutrients • Nutrients needed in very small amounts

11. Major plant nutrients • Consist of: • Nitrogen (N) • ________________ (P) • Potassium (K) also called Potash • Major plant nutrients are listed on fertilizer bags • %N, %P, %K • Form of nutrients will be listed in smaller print

12. Nitrogen • Nitrogen under goes a cycle in environment • N is essential building block of plants. Used in: • Proteins • Plant pigments • _________________ • Secondary metabolites • Plant hormones (i.e. _____________) • Needed in largest amounts • Most N is in atmosphere • In soil most N is in organic matter • Unavailable to plants

13. Nitrogen • Plants absorb the nitrate form of N • The nutrient most likely to be deficient • Ways nitrogen becomes unavailable to plants • _______________ • Downwards movement of N and other nutrients in the soil solution • Runoff when bound to clay or organic matter • Harvest of crops • Denitrification • In ___________________ soils, N can be converted by microbes into atmospheric N

14. Nitrogen • Nitrogen deficiency • Symptoms: ____________________ of the leaves, especially the older leaves • Treatment: apply a material high in N • Excess nitrogen • Easy to over apply nitrogen • Will cause: • ______________ maturity • Uneven ripening • Overly succulent _________

15. Phosphorous (P) • Plants use phosphates • Phosphates can be ____________ pollutants • Most soils contain large amounts of P but not in forms available to the plant • Functions • It is important for use and storage of energy • Stimulates root, fruit, and seed development

16. Phosphorous • Phosphorous deficiency • Symptoms: Slight stunting of the plant, older leaves will be _______________, and undeveloped root system • Treatment: • Apply ___________ meal • Apply a synthetic fertilizer containing a high level of P • Phosphorous does not move much in the soil

17. Potassium (K) also known as Potash • Where did the name potash originate? • Considered to be in the form of K2O • Not _______________ readily • Is essential for synthesis of proteins and carbohydrates • Is needed in higher amounts by root crops • Organic fertilizers are often low in K

18. Potassium • Potassium deficiency • Symptoms: • Small inferior flowers and fruits and _________________ plants. • Yellowing along the edges of older leaves • Leaves become _________________ • Treatment is to apply a fertilizer high in K

19. Secondary Nutrients Calcium • Plays an important role in _______ wall development • Calcium deficiency problems: • Calcium deficiency is rare but plants sometimes cannot adequately distribute calcium

20. Calcium • Symptoms • ____________ in lettuce and cabbage • Blossom-end rot in tomatoes • Treatment • There is no immediate “cure” for calcium deficiency problems • Adding materials high in calcium will not solve the problem • Maintain even watering • ________________ the plants • Maintains more even soil moisture

21. Secondary Nutrients Magnesium • Magnesium deficiency • Symptoms: yellowing starting between the _____________ of the older leaves Sulfur • Generally not a problem • Used for making soils more ____________ and is found in compost and manures

22. Micronutrients Introduction • Are needed in very small quantities • Generally all micronutrients are available in _________________ materials you apply to the garden • Best treatment is to prevent the problem from occurring in the first place • Availability is determined by soil _________

23. Micronutrients • Examples of important micronutrients • Iron: needed in synthesis of _____________ • _________ • Boron: deficiencies are more likely on ________________ soils • Molybdenum: deficiency generally due to acid soil conditions

24. Cation Exchange Capacity (CEC) • It is the ability of clay, organic matter, and ________________ to attract positive ions • Clay, organic matter, and humus all have ___________ charges on their surfaces • Most nutrients (P, K, Ca, etc) are _____________ or have positive charges • “Opposites attract”

25. Soil pH: Acidity and Alkalinity • What is pH? • pH is –log[H+] • pH is a scale from 1 to ______ • Why is pH important? • Because nutrients are more or less available depending on the soil’s pH • The ideal range is 6.2 to ______

26. Soil pH • Influences disease problems • Acid soils promote ____________ root disease of cabbage • Adjusting the pH • ___________ is used to raise the pH • Sulfur is used to ___________ the pH