"The Knowns and Unknowns of Nutrient Uptake" Roch Gaussoin, PhD University of Nebraska-Lincoln

Transcription

1 "The Knowns and Unknowns of Nutrient Uptake" Roch Gaussoin, PhD University of Nebraska-Lincoln

2 What we know now What we will know in the future

3 Plant Nutrient Application Solid fertilizers Liquid fertilizers Organic fertilizers Inorganic fertilizers Foliar feeding Root feeding

4 Nutrient Absorption Granular fertilizers - root absorption Liquid fertilizers - root and foliar absorption Foliar feeding - foliar (total or partial?)

5 Foliar Nutrition Research: A historical perspective

6 Foliar uptake is well documented Turf info, until recently, was limited

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8 Permeation of Nutrients via Cuticular Nanopores Small neutral molecules move more readily Monovalent greater than divalent ions K+ > Mg++ High concentration may overcome repulsion Permeation greater when nutrients are in solution than when dried on surface

9 Diameter of Hydrated Cations & Cuticular Penetration Rates Permeability CoEfficients of Cations (k/k (Li + ) 0.5 M) K + > Na + > Mg +2 > Ca +2 >> Fe Diameter of Hydrated Cations (nm) McFarlane & Berry 1974 Mengel & Kirkby 1978 The rate of cuticular permeation decreases as hydration diameter of monovalent cations (size) increases. For divalent cations, increased hydration weakens charge strength and promotes greater permeation. NH 4 + > K+ > Na+ > Ca 2 + > Mg 2 +

10 Ectodesmata - pores with a diameter of less than 1 nm. These pores are readily permeable to solutes such as urea (radii 0.44 nm), but not larger molecules.

11 Cool-Season Grass Leaf Surface

12 Nutrient Absorption into Leaf Cells Nutrients absorbed through leaves enter the cellulose cell walls (apoplasm) of leaves just as ions absorbed by roots and transported through the xylem would. Nutrient ions are absorbed by leaf cell protoplasts just as they would be by root cells.

13 The first reports on foliar application of mineral nutrients in plant production date back to the second half of the 18th century Most studies on the uptake of mineral nutrients and their translocation within a plant were carried out after the Second World War (advent of radio isotopes)

14 The most studied foliar nutrient is nitrogen - 30 to 99% foliar absorbed

15 Comparative nutrient recovery in crops Nitrogen (48 hrs post application) % Soil Applied % Liquid Applied 10 to 40 % sorghum & cotton 31 to 99 % tomato, corn & turfgrasses Do not over think this granular fertilizers have slower release mechanisms than do nutrients in solution

16 What about turf? Minimal research until recently Turf system is very different leaf surface exposure plant density proximity to soil mowing irrigation stresses

17 X X X X X What may happen to nutrients applied to turf leaves?

18 Uptake of Foliar Nutrients on a Putting Green Conducted in Nebraska (L-93) Conducted in Nebraska, Michigan (Poa & Bent) & South Carolina in 2006/07 (Champion Bermudagrass) Florida 2007 on Paspalum Univ of Nebraska, Michigan State Univ (Kevin Frank), Clemson University (Haibo Liu) & Univ of Florida (John Cisar) 3 Treatments (Peter s ; Grigg Bros Tournament Program; Untreated) 2 times of year (cool vs. hot) Not with radio-isotopes uptake by subtraction Funded by

19 California green, L-93, 3 years old, 0.11 mowing height

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25 - amount applied per unit area (from food saver) - amount in untreated (from wash) - amount in wash = (amount absorbed)

26 Percent Uptake Creeping Bentgrass (L-93) University of Nebraska N P K Minutes After Treatment

27 Percent Uptake Creeping Bentgrass (L-93) University of Nebraska Minutes after Treatment B Ca Cu Fe Mg Mn Zn

28 Percent Uptake Creeping Bentgrass (L-93) Michigan State University Minutes after Treatment N P K

29 Percent Uptake Annual Bluegrass Michigan State University Minutes After Treatment N P K

30 Increase in absorption for foliar vs soluble for nutrients statistically different N Fe Mn Cu B Ca* Mg* Bent UNL 4.4X 1.3X 2.8X 1.4X 19.2X 72% 61% Bent MSU 1.3X 5.3X 3.5X NS 4.0X 62% NA Poa MSU 1.4X 8.0X 7.9X NS 4.0X 61% NA Bermuda 1.1X 1.6X 9.8X NS 3.0X 97% 92% *Not in soluble product; data indicates maximum absorption NA = not applied In all elements the increase in efficiency was always attributed to the foliar product (of the products tested)

31 Foliar uptake of nutrients applied in solution to Creeping Bentgrass (Agrostis palustris Huds.), Annual Bluegrass (Poa annua var. reptans (Hausskn.) Timm) and Ultra-Dwarf Bermudagrass (Cynodon dactylon x C. transvaalensis Burtt-Davy). Gaussoin, Roch, University of Nebraska-Lincoln; Schmid, Charles, University of Nebraska-Lincoln; Frank, Kevin, Michigan State University; Butler, Tim, Michigan State University; Liu, Haibo, Clemson University; Jarvis, William III, Clemson University; and a few more.. Will also be posted to turf.unl.edu

32 Potential Losses Leach to soil No irrigation or rainfall during trials Bound in thatch/om Wet chemistry analysis of N and P show no increased levels in thatch/om Mowed off Possible depending on product/timing Volatility U of Arkansas M. Richardson = minimal loss

33 Why the difference?..between University of Arkansas and University of Illinois Formulation differences, as well as carrier volume

34 % Absorbed Does spraying time affect absorption? AM Spray vs. PM Spray B Ca Cu Fe K Mg Mn NH4 NO3 P Zn Elements AM Spray PM Spray AM Spray = 52 O F, PM Spray = 71 O F

35 Percent Uptake Creeping Bentgrass (L-93) University of Nebraska Temperature (F o ) B Ca Fe K P Zn

36 Work was also done in greenhouse under controlled conditions

37 How quickly can the nutrient get into the leaf? Does shade or cultivar affect absorption?

38 How quickly does the nutrient get into the leaf? Intake is rapid, often within 15 minutes Carrier will influence speed

39 Shade Effects Initial uptake (i.e. first 15 minutes) is impeded by shade Shaded turf 6 hrs) is at or near un-shaded Shaded turf should be mowed first, delay irrigation or mowing if possible

40 Cultivar Effects For some nutrients, the denser cultivar delayed or slightly impaired uptake (density?) This was especially true of Mn A good spreading agent may eliminate this impairment

41 Summary: Temperature Summer/Fall Time of day Element Source Spray volume Shade Cultivar Nutrients applied to turf can be foliar absorbed

42 Agronomic Law of Minimum 13 essential elements besides C, H, O 2 are required -- Growth and health will be limited by the lowest optimum level present No element may substitute for any other Roots at times and under certain conditions are limited in their uptake of nutrients

43 General information about liquid fertilization In general, our cultured plants take up necessary nutrients from the soil. A healthy root zone comes first. Foliar nutrition is a supplement to soil nutrition, not a substitute for it.

44 General information about foliar fertilization Even if there is optimum level of nutrients in the root zone, it may not be readily available Circumstances exist where foliar fertilization is a viable supplement to soil fertilization

45 Other Benefits..

46 Do you use any of the following in your liquid program? Cytokinin Amino Acids Biostimulants Phosphites % 66% 74% 86%

47 Spray Solution Effects Surfactants/Adjuvants Beneficial to critical ph Slightly acidic to neutral

48 Liquid fertilizer effects on spray solution ph ph 7.0 ph 8.0 ph 10.0 Water ph Ultraplex Urea AmS O 4 F es O 4 Urea + F es O 4 AmS O 4 + F es O C ontrol

49 ph of water used for liquid application < >8.0

50 Previous Surveys Summary 36% use a buffering agent in their spray solution

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55 Precipitate Formation FeSo 4 = precipitate at ph = 8 & 10 Foliar (buffered) solution no precipitate Weight equaled ca. 60% of what was initially dissolved In 100 gallons = ca lbs FeSO 4 Foliar

56 How do you know if you need a buffering agent? Recommended on label ph >7.5 Tank mixing multiple products

57 When applying liquid fertility applications, do you tank mix with PGRs and/or fungicides?

58 How do you know your spray solution ph? Measure it, but how? How accurate do you need to be? When should you test? For some water sources, ph fluctuates with season, test frequently

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60 Could you create your own true foliar product? Maybe, but why? Solubles, granulars and foliars can all be used to improve management options. Reducing, not eliminating, costs is critical. Choose the cost reduction that will have the most economic benefit and least agronomic deficit.

61 If you are using liquid applications, do you use: GB, EI, FL, MS or similar Solubles Ag Grade Combination of above

62 Be thankful for what you have and always share with those less fortunate