Overall Limestone Model Understanding pH dynamics of liming materials in container substrates. Jinsheng Huang and Paul Fisher LimeR Series Analyzing Lime in Container Substrates

pH drift is common. Multiple factors and low buffering. pH balance BASIC (increase pH) Nitrate NO 3 ACID (lower pH) Ammonium NH 4 LimeAlkalinity Media Species - +

Purposes of Liming Initial pH pH buffering Supply Ca, Mg Lime pH effect depends on: –Reactivity –Requirement –Residual

Generalized model of lime reaction pH init pH Max pH=pH init + pH Max (1-EXP(kt)) k = f(particle size, chemical form, temperature, moisture) pH Max = f(lime acid neutralizing value, lime concentration, lime solubility, media buffering)

Objectives Predict and understand pH response of lime in a container substrate. Applications Lime, media analytical tests Match lime rate and type to substrate Assist in R&D of substrates

Lime Reactivity: solubility

Solubility: model with two-phase function Plateau Linear

Lime Reactivity: particle size

Particle Size Efficiency (PSE) factors = pH response at day 7/pH response from reagent CaCO 3 Particle size ( µ m) Calcitic limestone Dolomitic limestone µ m (10-20 mesh) µ m (20-60 mesh) µ m ( mesh) µ m ( mesh) µ m ( mesh) <45 µ m (passes 325 mesh)

Lime Reactivity: particle size Particle size ( µ m)kA µ m ( mesh) µ m (20-60 mesh) µ m (10-20 mesh) PSE = A(1-EXP(kt))

Lime Reactivity: substrate moisture and temperature

Lime Requirement: substrate buffering

Lime Residual Example of one lime source and substrate

Lime Residual Not all lime reacts. What is left is residual lime.

Lime Residual: provides buffering No residual Residual Impatiens Acid fertilizer

General procedure HortScience 42(7): mL sample 25 mL 6M HCl 50 ml substrate + 75 ml deionized water in flask Close system and dispense 25 ml 6M HCl Moles of CO 2 by volume displacement Residual lime in substrate can be calculated using Ideal Gas Law CO 2

Lime Residual: change over time

LimeR application

Thank You Jinsheng Huang Kate Santos Angelica Cretu Connie Johnson Ernesto Fonseca Easton Horner Becky Hamilton Dustin Meador Bill Argo, Blackmore Co. Paul Nelson, North Carolina State Univ.

Research partners (Univ. of Florida, Univ. of Minnesota)Research partners (Univ. of Florida, Univ. of Minnesota) –Leading Media and Fertilizer Companies: –Leading Growers: -AgriStarts (FL), Altman Plants (CA), D.S. Cole Growers (NH), Four Star (MI), Florida Plant Specialists (FL), Knox (FL), Kube Pak (NJ), Lucas (NJ), Pleasant View Gardens (NH), Spring Meadow (MI), Smith Gardens (WA), Twyford (FL), Wagners (MN), Welby Gardens (CO) Research partners (Univ. of Florida, Univ. of Minnesota)Research partners (Univ. of Florida, Univ. of Minnesota) –Leading Media and Fertilizer Companies: –Leading Growers: -AgriStarts (FL), Altman Plants (CA), D.S. Cole Growers (NH), Four Star (MI), Florida Plant Specialists (FL), Knox (FL), Kube Pak (NJ), Lucas (NJ), Pleasant View Gardens (NH), Spring Meadow (MI), Smith Gardens (WA), Twyford (FL), Wagners (MN), Welby Gardens (CO) 2008 Donors PINDSTRUP MOSEBRUG A/S