Nutrient Management of Container Nursery Crops

Transcription

1 Nutrient Management of Container Nursery Crops Bert Cregg, Ph.D. Michigan State University Department of Horticulture Department of Forestry Photo: Dennis Fulbright Why worry about nutrition management? Fertilization is one of the most important tools for managing crop growth and quality Nutrition is one of the most common sources of plant problems Grower efficiency/cost concerns Environmental concerns/ Sustainability Presentation outline Plant nutrition Substrates and Irrigation Nutrition management Fertilization strategies Diagnosing nutrient problems Summary Essential elements for plants Chart:mosaic.com 1

2 Poor plant nutrition can lead to deficiency symptoms and reduced growth Relationship between plant growth and nutrient concentration Adapted from Landis et al. (1989) Keys to successful container production Substrate Irrigation Nutrition 2

3 Container substrates Container substrate should provide: Support/Anchorage Water Holding Capacity Aeration/Drainage Light Weight Easily available and consistent quality Affordable priced Nutrient Reservoir (CEC) Cation Exchange Capacity (CEC) What is a cation? Cations are positively charged elements in the soil Common nutrient elements that occur as cations are K +, Mg +2, Ca +2, NH 4 + Other cations are also taken up by plants; Al +3, Na +2 Softwood bark Pine and Douglas-fir bark Good, light-weight substrate. Low ph so excellent substrate. Good CEC Good WHC 3

4 Other Materials Optimal substrate may vary by plant type Perlite Vermiculite Composted materials Sand Irrigation Soil ph Measure of acidity of soil ph = log (1/H + ) Acidic Neutral Basic 4

5 N P K S Ca Mg Fe Mn B Cu Zn Mo Container Substrate Optimum ph 5-6 ph above 6 will create deficiencies of P, Mn, B, Cu, Zn ph below 4.5 will create deficiencies of many essential elements Soluble Salts Naturally occurring Water Fertilizer Soil and water amendments Usually measured as : Electrical Conductivity (EC): ms/cm or ds/m or mmhos/cm 5

6 Measuring EC Pour-trough Desirable EC and Nutrient Concentrations for Soluble and Slow-Release Fertilization Soluble only or CR CR fertilizer Analysis & soluble only ph EC, ds/m (mmhos/cm) 0.5 to to 0.5 Nitrate N, (mg/l or ppm) 50 to to 25 Phosphorus, (ppm) 10 to 15 5 to 10 Potassium, (ppm) 30 to to 20 Water Quality Guidelines for Mature Nursery Crops NO3, EC and ph in response to CRF application Characteristic ph Alkalinity (ppm) Alkalinity (meq/l) EC (ds/m) SAR (ppm, root) Good < 60 < 1.0 < 0.75 < 3 Some Problem > Problem need mgt > 7.0 > 215 > 3.5 > 1.4 > 9 Klooster et al.,

7 Alkalinity and ph Alkalinity is much more important than ph Alkalinity relates to the ability of water to raise substrate ph Water with relatively high ph and low alkalinity may not affect substrate ph Water with relatively high ph and high alkalinity will increase substrate ph Liquids: Managing Alkalinity Acids to Inject Nitric available at 61.4% or 67% Sulfuric available at 93% and 35% Phosphoric available at 75% and 85% Solid: Citric- more expensive but does not change nutrition program Irrigation amounts Common rule of thumb for container irrigation is ¾ per day for overhead irrigation Probably excessive: Deficit irrigation studies indicate water use can be reduced considerably w/o reducing growth 7

8 Leaching fraction LF = amount leached amount applied Deficit irrigation 10-20% leaching fraction typically recommended to eliminate build-up of salts Beeson 2006 Summary NO3, ph, and EC in response to irrigation amount Substrate ph affects nutrient solubility/availability Irrigation rate affects leaching (potential waste of fertilizer) Water quality and irrigation rate affects substrate ph and leaching CRFs can be selected to help manage alkaline water 8

9 Nutrient management Fertilizer options for container production Compost Granular fertilization Controlled release fertilizer (CRF) Fertigation Combination General Nutrition Program Primarily based on N levels Ratio of 3:1:2 for N, P 2 O 5, K 2 O (some are trying 3:0.5:2 ratio including our WateR3 project) N- 0.1 ounce/1 gallon pot (~3 g/gal.) Major fertilizer manufacturers rates: High, Medium, Low are usually appropriate, MSU Nursery goes with Medium or Low rate General Nutrition Program (cont.) Ca- usually no need to apply in most of Michigan if using well water except as ph amendment Mg- usually no need to apply in most of Michigan if using well water, if needed use dolomite instead of limestone if need to raise ph or magnesium sulfate if ph ok Standard CRF s include micros 9

10 Controlled-release (Slow-release) forms of N Urea-formaldehyde (UF) (38-0-0). Isobutyldiene diurea (IBDU) (31-0-0) Sulfur coated urea (SCU) (36-0-0) Plastic coated fertilizers (various formulations). Natural organics--sewage sludge, etc. Simonne and Hutchinson HortTech 15: Fertilizer options for container production CRF Release rates are based on standard, constant temperature Rule of thumb: 2-3 g of N per gallon container Example 3 gallon container product 3 gal x 3 g N / 0.15 = 60 g CRF per container 10

11 Response of shade trees to CRF Growth peaked at 60 g N/tree = 400 g product = manufacturer s recommendation Klooster et al., 2012 Fertilizer placement? Top-dress Incorporated 11

12 Fertilizer placement Typically little effect on growth Decision largely driven by logistics Top-dress Good for re-application Blow-over issue Incorporate Less time, labor Potential loss to leaching before roots occupy container Water soluble fertilzier Fertilizer options for container production Fertigation continuous feed Pre-packaged water soluble formulations available Also possible to blend your own See USFS Container Tree Nursery Manual Vol. 4 Rule of thumb: ppm N 12

13 Photosynthetic response of firs to fertigation 13

14 Diagnosing deficiency Symptoms Part of plant affected Chlorosis, Necrosis Pattern, I.e. interveinal Vs. whole leaf Other causes evidence of pathogens, insects, water stress Foliar nutrient analyses Sample recently expanded foliage Keep track of time of year when sampled Deciduous -> Mid-late summer Conifers -> Early fall If possible, sample good and bad plants 14

15 Diagnosing chlorosis in maples N P K Mg low high B Zn Mn ID N % P% K% Mg % Ca% S% ppm ppm ppm Freemani 'bad' Freemani 'good' Red maple 'bad' Red maple 'good' Sources of information N P K Mg low high University and county extension State and local nursery associations Professional irrigation, chemical, and substrate supplier Trade publications (e.g., American Nurseryman, State Nursery Association Magazine) Websites 15

16 Foliar fertilziation Sources of information Essentially a quick fix Typically treating symptom not problem Sources of information Summary Interactions between irrigation, substrate, and nutrition are critical Need to account all nutrients in a container program Amount? CRF: 2-3 g N/gal Soluble: ppm N Manufacturer s recommendation 16

17 Summary (cont.) Regular monitoring is critical Irrigation water quality Irrigation amount Leachate EC and ph (pour-through) Record keeping is essential Summary (cont.) Diagnosing nutrient issues is tricky Crop history Substrate/leachate testing Foliar sampling By the time you see visible symptoms, growth losses have likely already occurred Acknowledgements Tom Fernandez lab Dana Ellison Wendy Klooster Amanda Taylor ICL fertilizers 17

18 Thanks for your attention! 18