Soil Texture Discussion. Soils, Nutrients and Fertilizers Level 2. An Ideal Soil yes, soil, not dirt

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1 Soils, Nutrients and Fertilizers Level 2 Montana Master Gardener Handbook Chapter 1 pages 1 20 Adapted from a soils presentation from Clain Jones, PHD Extension Soil Fertility Specialist, Montana State University An Ideal Soil yes, soil, not dirt 50% Pore Space 25% Air 25% Water 50% Solid Material 5% Organic Matter 45% Mineral Soil Texture Discussion 1

2 Cation Exchange Capacity Indicates ability of soil to hold positively charged nutrients. Many essential plant nutrients carry positive charges. Example: Potassium (K + ) A fertile soil has the capacity to attract and hold these nutrients. Soils with large surface areas, such as clay and organic matter, have more CEC and surface area and therefore are generally more fertile. Texture Effects on Soil Properties Drainage Water holding capacity Aeration CEC Sand excellent poor excellent low Silt good good good med Clay poor excellent poor high Irrigation a balance between soil nutrient retention and encouraging deep root growth. What would you recommend? 1. Daily light watering inches a week 3. Several inches when the soil has dried in the root zone 2

3 Irrigation a balance between soil nutrient retention and encouraging deep root growth. What would you recommend? 1. Daily light watering inches a week 3. Several inches when the soil has dried in the root zone ph affects soil nutrient availability ph affects soil nutrient availability Most Montana soils are generally alkaline 3

4 ph affects soil nutrient availability Many mountainous or areas in the NW part of the state may have acidic soils ph affects soil nutrient availability Generally, the ideal soil ph is about 6.8 Soil ph which is true? 1. Is difficult to alter 2. Has no influence on nutrient availability 3. Most vegetables prefer ph > 7.5 4

5 Soil ph which is true? 1. Is difficult to alter 2. Has no influence on nutrient availability 3. Most vegetables prefer ph > 7.5 Why are MT soils high ph? Most MT soils are highly calcareous = alkaline Even if surface soil isn t alkaline, the subsoil usually is Liming to increase ph doesn t make sense in our soils Mollisol common in Montana and or semi arid regions 14 mineral nutrients have been found essential for growth of most plants: Macronutrients Nitrogen (N) Phosphorus (P) Potassium (K) Sulfur (S) Calcium (Ca) Magnesium (Mg) Micronutrients Boron (B) Chloride (Cl) Copper (Cu) Iron (Fe) Manganese (Mn) Molybdenum (Mo) Nickel (Ni) Zinc (Zn) The macronutrients are simply needed in larger amounts by the plant than the micronutrients. Nutrient deficiencies of the bolded nutrients have been observed in Montana 5

6 What is the best option to lower ph in highly calcareous soils? 1. Add elemental sulfur (S) 2. Add gypsum (CaSO 4 ) 3. Add pine needles 4. No reasonable option to lower significantly What is the best option to lower ph in highly calcareous soils? 1. Add elemental sulfur (S) 2. Add gypsum (CaSO 4 ) 3. Add pine needles 4. No reasonable option to lower significantly Adding elemental sulfur Consequences? April 5 months later Costs? 7.8 l ph Soi Sulfur Added (lb/1000 sq. ft.) AgVise Laboratories 6

7 What might happen if you add 230 lbs S/1000 sq. ft.? 1. You spend $366/1000 sq ft 2. Your soil ph will drop by at least 1.5 units 3. Soil S levels will remain well below toxic 4. Soil salt levels will improve What might happen if you add 230 lbs S/1000 sq. ft.? 1. You spend $366/1000 sq ft 2. Your soil ph will drop by at least 1.5 units 3. Soil S levels will remain well below toxic 4. Soil salt levels will improve Same study site added 115 lbs gypsum /1000 sq. ft. with no change in soil ph Questions? 7

8 14 mineral nutrients have been found essential for growth of most plants: Macronutrients Nitrogen (N) Phosphorus (P) Potassium (K) Sulfur (S) Calcium (Ca) Magnesium (Mg) Micronutrients Boron (B) Chloride (Cl) Copper (Cu) Iron (Fe) Manganese (Mn) Molybdenum (Mo) Nickel (Ni) Zinc (Zn) The macronutrients are simply needed in larger amounts by the plant than the micronutrients. Nutrient deficiencies of the bolded nutrients have been observed in Montana Most common lacking nutrient is nitrogen (N) Volatilization NH 3 Organic material Harvest Plant Up ptake Fixation N 2 Gas ification Denitri Needed for growth of shoots and leaves NH 4 + Clay or OM Exchange NO 3 Leaching Mineralization Release of minerals as organic matter (O.M.) is oxidized, releasing available N Organic N Plant Available N Immobilization Incorporation of available N into microbial cells or plant tissue Plant Available N Organic N This is why you need to add extra N when using high C organic material (like straw). 8

9 Phosphorus (P) Movement of P is largely through erosion/runoff, NOT leaching. Why? P binds strongly to soil Organic material Needed for seed and fruit ripening, maturation, energy storage/transfer Harvest Exchange HPO 4 2 Erosion & Runoff Plant U ptake Fe or Al oxide Precipitation Dissolution P mineral Potassium (K) Needed for gas exchange, new root and stem growth, hardiness, fruit flavor and color Harvest t Release Plant Erosion & Runoff Plant Upt take Mineral Soil Solution K Exchange Weathering Clay Leaching Sulfur (S) Harvest Needed for protein synthesis and N utilization. Formerly a byproduct of fertilizer synthesis and coal/oil burning lant Uptake Pl Soil Solution SO 4 2 H 2 S SO 2 Atmospheric Deposition Organic material Volatilization Mineral Exchange Fe or Al oxide Leaching 9

10 14 mineral nutrients have been found essential for growth of most plants: Macronutrients Nitrogen (N) Phosphorus (P) Potassium (K) Sulfur (S) Calcium (Ca) Magnesium (Mg) Micronutrients Boron (B) Chloride (Cl) Copper (Cu) Iron (Fe) Manganese (Mn) Molybdenum (Mo) Nickel (Ni) Zinc (Zn) The macronutrients are simply needed in larger amounts by the plant than the micronutrients. Nutrient deficiencies of the bolded nutrients have been observed in Montana Boron Deficiency Young leaves of terminal bud become light green at bases; leaves become twisted and brittle and die back at growing point; chlorosis of young leaves Plants initially may not exhibit obvious symptoms of nutrient deficiencies other than a slower growth rate, which may be due to other factors. Add borax 1 tablespoon per gallon per 100 sq.ft Easy to have a toxicity, so test first Wilting Leaf mottling with tip chlorosis May look like disease orinsect damage Chloride Deficiency Usually added with other nutrients such as potassium chloride 10

11 Chlorosis of young leaves; tips appear withered and will eventually die Copper Deficiency Copper sulfate Manganese Deficiency Yellowing, cupping and/or spotting of leaves, stunted growth, andreduced crops Manganese sulfate small, narrow leaves with black spots in yellow areas; plants may be stunted Zinc Deficiency Zinc Sulfate 11

12 Addition of micronutrients Go to your local nursery or garden center Read the label Manure a good source of micronutrients Make sure that the manure is fully composted and contains no residual herbicides! How to evaluate soil nutrient status Visual assessment of tissue: May identify what has been lacking to this point S il ll h i l il bl Soil test: Tells you what is currently available in the soil, useful to calculate nutrient addition rates, estimate of what will be available for that growing season 12

13 Visual tissue assessment Nutrients that are mobile in the plant will affect lower leaves first. IMMOBILE NUTRIENTS* Boron Calcium Copper Iron Manganese Sulfur Zinc These include: Nitrogen (N) Phosphorus (P) Potassium (K) * NM/Modules/Module9.pdf 1. N 2. P 3. K 4. Sunshine 5. Fe What nutrient is lacking? 1. N 2. P 3. K 4. Sunshine 5. Fe What nutrient is lacking? 13

14 Nitrogen Deficiencies Deficiency : Chlorosis (insufficient chlorophyll) in older plant tissue (Shows up in older leaves) What nutrient is lacking? 1. N 2. P 3. TLC 4. S 5. Fe Soy bean RJ Goos, NDSU What nutrient is lacking? 1. N 2. P 3. TLC 4. S 5. Fe Soy bean RJ Goos, NDSU 14

15 Fe deficiency in rose. Chlorosis between veins especially on younger or upper leaves. Highly susceptible plants include raspberry, Amur maple, crabapple, mountain ash, and roses What nutrient is lacking? 1. N 2. P 3. K 4. S 5. vinegar and oil What nutrient is lacking? 1. N 2. P 3. K 4. S 5. vinegar and oil 15

16 P deficiency in tomato. Dark green foliage with purple stems or leaves especially on the underside. Healthy vigorous plants that don t flower to produce fruit. Pseudo deficiencies What else can cause symptoms that look like nutrient deficiency symptoms? 1. Insects 2. Salinity 3. Moisture stress 4. Disease 5. Herbicides Photo: Ontario Ministry of Ag., Food & Rural Affairs Questions? 16

17 Why soil test? To identify nutrient deficiency or imbalance To help calculate fertilizer rates Can increase yieldand/or save on fertilizer costs, and decrease environmental risks Soil testing Sample top 0 6 inches Combine 10 subsamples per 1000 sq. ft. Use probe, auger or tulip bulb planter Best done in early spring, but not when soil is wet, therefore in our climate perhaps best done in late fall 17

18 What if lab doesn t provide a recommendation (or is from another state)? Use Table 3 from MontGuide (MT200705AG) Soil Test Organic Matter (%) Nitrate N Location < > 3.0 lbs /acre lbs/1000 sq.ft. < >40 Lawn Tree/shrub Garden Lawn Tree/shrub Garden Lawn Tree/shrub Garden Application considerations Conventional Apply and incorporate before maximum uptake which is BEFORE max biomass most nutrients are in the plant early and translocated to the maturing fruit Sideband P and K near, but not with the seed Side dress additional N mid season, if needed Organic material Takes time to decompose and become available N may be tied up in the short term Slow Release Fertilizers These release quickest in warm moist environments. Incorporate and apply early in growing season or use blend of quickly available source and slow release. 18

19 Considerations when fertilizing with manure Easy to over apply N, P, and K Rapid excess buildup of P and K if fertilizing to meet N needs Of 67 Midwest gardens 92% had excess P and 88% excess K after just 1 to 6 years of uninformed fertilization with composted dairy manure (Hansen unpub data, Ohio State Univ) Feed to P and K demands Use legumes or source such as blood meal to supply N Approximately how much total N, P, and K does 1 of manure compost supply? Removed annually Added by 1 manure N P 2 O 5 K 2 O lbs/1000 sq. ft Nutrients removed by one season s harvest of the edible portion of garden vegetables Crop N P 2 O 5 N:P ratio lbs/1000 sq. ft. Broccoli :1 Lettuce :1 Pepper :1 Sweet corn :1 Tomato :1 Average :1 One local composted manure tested had a total N:P of 6:1 Morris, Ping, and Durgy. University of Connecticut. 19

20 How much organic matter? 1 manure compost will add about 1.5% O.M. 1 plant compost will add about 3% O.M. Why the difference? Manure compost 20% O.M. Yard/kitchen compost 40% O.M. 5 8% O.M. is optimal O.M. is not the cure all for all soil ailments. Sand may be the missing element to improve tilth and aeration. Adding organic material is good, but how can you increase soil organic matter without adding too much P and K? Add organic matter high in C (dry leaves, wood shavings, straw, peat), but remember, immobilization happens Add organic matter based on plant s P needs and add N with chemical fertilizer, organic fertilizer such as blood meal, or plant legumes Which is true about using legumes to supply N? 1. Legumes fix very little of their own N if soil N is sufficient 2. Legumes seeds must be inoculated before planting 3. The rhizobia that help legumes fix N are not legume specific 4. Soil critters not used to legumes get digestive upset 20

21 Which is true about using legumes to supply N? 1. Legumes fix very little of their own N if soil N is sufficient 2. Legumes seeds must be inoculated before planting 3. The rhizobia that help legumes fix N are not legume specific 4. Soil critters not used to legumes get digestive upset Which bean plant is/was actively fixing N? Summary Understanding deficiencies and imbalances is important to optimize nutrient use leading to maximum plant health and yields Soil testing is an important tool to help prevent or correct plant growth problems The foundation of a healthy garden is a healthy soil 21

22 Questions? For additional information on nutrient ti t cycling and fertilization 22