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Matt Ruark Dept. of Soil Science A.J. Bussan Dept. of Horticulture

OUTLINE Soil and plant testing Tomato U W nutrient guidelines N utrients of concern Pepper U W nutrient guidelines N utrients of concern

SOIL AND PLANT TISSUE TESTING S oil tests let you know where to start M onitoring plant "health" helps to know how to adjust. N ot all micronutrients have soil tests N ot all nutrient deficiencies are caused by lack of soil nutrients


Take soil sample from area where plant samples were taken

Compare "bad" and "good" parts of the field ­ improves the diagnosis!

PLANT TISSUE SAMPLING Recommendations for sampling: Tomato: collect mid-season, newest fully developed leaf, 40 plants/sample P epper: collect prior to or at early fruit development, collect petiole and leaflet, 40 plants/sample W ipe off dirt, do not wash! U WEX does not have recommendations for petiole sap testing for pepper

ORGANIC MATTER & P H T he OM measure helps place soil into category for N recommendation: < 2%, 2 to 10, 10 to 20, >20 Target pH for tomatoes and peppers: 6 .0 for mineral soil 5 .6 for organic soil

TOMATO N itrogen (N) R ecommendations based on 20-25 tons per acre of fresh weight yield

Organic Matter (%) <2% 2 to 10 10 to 20 >20% N rate 140 120 100 50

TOMATO N itrogen (N) S andy soil ­ consider split application, some preplant (20 to 40), remainder at or after first fruit set. T he best split-applications may be more of an art than science. G oal is to maximize efficient use of N, while not over-promoting vegetative growth.

TOMATO P and K P : 1.8 lb P 2 O 5 = 1 ton yield K : 8.0 lb K 2 O = 1 ton yield

VL P K 115 L 90 Opt H VH lb of P2O5/ac 40 20 90 45 lb of K2O/ac 280, 240, 180 305 265 0 EH 0

TOMATO Ca, Mg, S F ollow soil tests, plant tissue tests if needed L iming materials may contain adequate amounts of Ca or Mg G ypsum is a good source of Ca & S ... but remember, gypsum will not change pH!

LIMING MATERIALS D olomitic = CaCO 3 ·MgCO 3 C alcitic = CaCO 3 F ly ash = CaO, Ca(OH 2 ), CaCO 3 G ypsum = CaSO 4 CaCO 3 + 2H + = Ca 2+ + CO 2 + H 2 O

The carbonate affects the pH ­ not the calcium!


Micronutrients F ollow with plant tissue tests B oron and Copper are of main interest F oliar application of B not as effective, difficult to translocate out of plant tissue ... but foliar is often the only application method in-season. ... but B can be toxic at high levels ­ apply B, follow tissue samples, stop B applications when B becomes excessive

TOMATO Importance of B studies have shown... A pplication of B increases K in leaf tissue and fruit I ncreases yields

H igh pH (>7.5) B concentrations of1.5 and 0.1 ppm - both field showed a response to application (Huang and Snapp, 2009; MI)

TOMATO G ray wall or blotchy ripening A ssociated with: L ow K, low B, high N

PEPPER N itrogen (N) rate B ased on yield goal of 8-10 tons ac -1

Organic Matter (%) <2% 2 to 10 10 to 20 >20%

N rate 100 80 60 30

PEPPER P and K P : 1.1 lb P 2 O 5 = 1 ton yield K : 5.6 lb K 2 O = 1 ton yield

VL P K 85 L 60 Opt H VH lb of P2O5/ac 10 50 5 25 15 lb of K2O/ac 150, 110, 175 135 0 EH 0

PEPPER U W recommendations do not rank secondary micronutrients for pepper. U se plant tissue testing


Blossom end rot R elated to Ca deficiency C aused by low Ca fertility C aused by water stress C aused by excessive N or K fertilization

N encourages excessive vegetative growth K leads to high soluble salt concentrations in soil and can restrict water uptake and thus Ca.

C aused by anything that damages roots

Root interception ­ roots obtain nutrients by physically contacting nutrients in soil solution or on soil surfaces; - roots contact ~1% of soil volume; - mycorrhizal infection of root increase root-soil contact

H2PO4Mn2+ Zn2+ H2PO4Zn2+ H2PO4-

Mass flow ­ dissolved nutrients move to the root in soil water that is flowing towards the roots


Ca2+ NO3-


Diffusion ­ nutrients move from higher concentration in the bulk soil solution to lower concentration at the root; -In the time it takes NO3- to diffuse 1 cm, K+ diffuses 0.3 cm, and H2PO4- diffuses 0.05 cm





------- Percentage (%) Supplied by ------Nutrient Amount of Nutrient Required for 150 bu/a of Corn (lb/a) Root Interception Mass Flow Diffusion

N P K Ca Mg S

170 35 175 35 40 20

1 3 2 171 38 5

99 6 20 429 250 95

0 94 78 0 0 0

Barber, Soil Bionutrient Availability, (1984). Diffusion estimated be difference between total nutrient need and nutrient supply by root interception & mass flow.

TAKE HOME MESSAGES O ver-application of N = bad U nder-application of K = bad S ulfur ­ nutrient to watch! To avoid fruit quality issues, use plant tissue and soil testing for:

B oron C alcium



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