Lime - the foundation for soil fertility David P. Wall 1 T. Sheil 2 - - PowerPoint PPT Presentation

Lime - the foundation for soil fertility

David P. Wall1

• T. Sheil2, M. Plunkett1 & S.T.J. Lalor3

1,Teagasc, Johnstown Castle, Co Wexford 2, Alltech Crop Science, Dunboyne, Co Meath 3, Grassland AGRO, Dock road, Limerick

1 2 3 4 5 6 7 8 9 10 11 12 13 14

• Soil pH is the single most important chemical property of the soil

(like soil texture is to the physical properties)

• pH is a measure of hydrogen ion concentration (H+) soil solution.
• The pH scale ranges from 0 to 14, where 7 is considered neutral
• The pH scale is exponential

pH 6 is 10X more acidic than pH 7 pH 5 is 100x more acid than pH 7 Therefore every 0.1 pH drop is a significant

Typical pH range for Irish soils

What is soil pH?

Acid Neutral Alkaline

Wall, D.P. et al. Teagasc, Soil Fertility Conference, 2015

Plant root injury:(H+ & Al3

+)

• changes in root membrane permeability
• leakiness or loss of organic substrates & absorbed cations
• Increases Al3

+ availability which is toxic to plant roots)

• root tips can die and lateral root development is supressed

Plant tops:

• reduced transport of nutrients from roots

What effect does too much acidity have?

` 3 4 5 6 7 8 9 Soil pH

Acidic Soils Alkaline Soils

Phosphorus Fixation

High Med Low

Fixation by Iron & Aluminium Fixation by Calcium Plant Available P

D.P. Wall, 2015

Effect of soil pH on soil P availability

Wall, D.P. et al. Teagasc, Soil Fertility Conference, 2015

Why is lime important ?

Neutralises acidity to correct soil pH Supplies essential plant nutrients Ca (and Mg) Enhances soil biology and fertility

• Organic activity in soil

depends on soil pH

• Release of nutrients from
• rganic matter in soil
• Optimises nutrient

availability (stored and freshly applied nutrients)

Wall, D.P. et al. Teagasc, Soil Fertility Conference, 2015

500 1000 1500 2000

1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014

Tonnage of Lime ('000 t/yr) Year

Lime usage 1970 -2014

Wall, D.P. et al. Teagasc, Soil Fertility Conference, 2015

Lime CaCO3 + Acid 2H+ = Calcium Ca+2 + CarbonDioxideCO2+ Water H2O

• 1. Ground Limestone (60% carbonate CaCO3)
• Finely ground to react with soils
• (35%) <0.15mm & (65%) <3.35mm
• 2. Magnesium Limestone (40% MgCO3 60%CaC03 = 64.5% carbonate)
• Higher neutralising value /slower to react / Use on Mg deficiency soils
• 3. Granulated Liming Products
• Seasonal soil pH regulation / Similar to Fertilisers
• 4. Burnt Lime (CaO)
• Reacts faster?.
• 5. Hydrated lime (Ca (OH2))
• Reacts very rapid.

Main lime sources available

Ground limestone effect on soil pH

Grazed grassland with 200kg N fertiliser

5.0 5.2 5.4 5.6 5.8 6.0 6.2 6.4 6.6 1 6 12 18 24 30 36 42 Months after application

Lime Applied

Spring ‘11

Soil pH level

Target pH range

D.P. Wall et al., 2015

Wall, D.P. et al. Teagasc, Soil Fertility Conference, 2015

3 4 5 6 7 8 9 10 1 6 12 18 24 30 36 42 Months after application

Lime Applied

Spring ‘11

Ground limestone effect on soil P levels

Grazed grassland with 200kg N fertiliser

Soil test P (mg/L)

D.P. Wall et al., 2015

Wall, D.P. et al. Teagasc, Soil Fertility Conference, 2015

4.5 5.0 5.5 6.0 6.5 12 24 36 42

Control Ground limestone Calcium Oxide Granulated Lime

Months after application Soil pH level

Efficiency of Bag Lime Products

Ground limestone 7.5 t/ha Calcium oxide 2.5 t/ha (1:3 ratio) Granulated Lime 2.5 t/ha (1:3 ratio)

D.P. Wall et al., 2015

Wall, D.P. et al. Teagasc, Soil Fertility Conference, 2015

Effect of P and Lime of soil P availability

Sheil, Wall & Lalor, 2015, FAI

Wall, D.P. et al. Teagasc, Soil Fertility Conference, 2015

• 250
• 200
• 150
• 100
• 50

50 100 150 200

Change in soil Aluminium Al3+ (mg/kg)

Control Lime Only P only P & Lime Treatments applied to soil

Average change in soil test P across 16 Irish soils at 12 months after application

* Increasing soil pH (less acidity) decreases available Al concentrations and reduces Al-P bonding (fixation)

Effect of Lime on Aluminium availability

Sheil, Wall & Lalor, 2015, FAI

Wall, D.P. et al. Teagasc, Soil Fertility Conference, 2015

Average response across 2 sites

Effect of P and Lime of grass yield

Average soil pH: 5.2 6.4 5.2 6.4

D.P. Wall et al., 2015

Wall, D.P. et al. Teagasc, Soil Fertility Conference, 2015

• Target mineral soils is pH of 6.3 for grassland (for peats pH 5.5)
• Apply lime based on the soil test report
• Split lime applications when required rates exceed 7.5 t/ha
• Caution! reduce lime rates on high molybdenum (Mo) soils so

that pH does not exceed 6.2.

• Ground limestone is the most cost effective source of lime and can

be applied throughout the year when the opportunity arises.

• As a rule of thumb: leave ≥3months between lime application and

following with Urea or slurry application

• Maintaining soil pH at the target level will increase the release of

soil nutrients.

• Lime is the foundation of soil fertility and is a primary step to take

following soil sampling.

Lime - Best Management Practice

Wall, D.P. et al. Teagasc, Soil Fertility Conference, 2015