Control

LimeLo

w

LimeM

ed

LimeHigh

Gypsu

mLo

w

Gypsu

mM

ed

Gypsu

mHigh

Soda l

yeLo

w

P [

mg

(10

0 g

DM

so

il)-1

]

0.0

2.5

5.0

7.5

10.0

P [

g (1

00

g D

M p

lan

t)-1

]

0.0

0.1

0.2

0.3

0.4

ContentUptake

CATCAL

EUF F

bcca

cdc

abcabb

abcc

cacab

dd

abd

ab

abccc

abab

abbccaa

aabc

ca

ab

ceb

bcdd

CALSoilUptakeSoil CATSoil ContentPlantEUFF1

Soil EUFF2Soil

6.9 7.6 8.2 8.9 7.0 7.0 6.9 7.8pH47 82 123 183 141 313 594 26CaEUF

Calcium and pH value play an important role for the availability of nutrients in agricultural soils. Our study aimed (i) to quantify the effect

of liming on plant available phosphorus (P) depending on the period between liming and plant nutrient uptake and (ii) to investigate the

suitability of several soil analysis methods (EUF, CAT, CAL) to predict the amount of plant available P.

• Additives (Burnt Lime (CaO), Gypsum (CaSO4), Soda lye (NaOH)) were mixed into loessial topsoil material from two sites (Göttingen Ut3,

Ochsenfurt Ut4) in increasing amounts (low, medium, high level; equal amounts of hydroxide and calcium ions at each level; Tab. 1); 4

Tab. 1: Amounts of burnt lime, gypsum and soda lye added to the soil inthree levels based on equal amounts of OH- and Ca2+ ions.

HOLGER LEMME1 & HEINZ-JOSEF KOCH1

• The soil extraction methods EUF and CAL predicted the amount of P available for young sugar beet plants very well. To further optimizethe correlation between EUF P and plant P uptake, the amount of P in the LimeHigh treatment should be corrected.

• Increasing soil pH caused a substantial increase of plant available P (P content & P uptake), whereas the soil Ca content had no effect.

• These results must be confirmed by further investigations; fractioning the soil P is expected to give further explanations.

lemme@ifz-goettingen.de1 INSTITUT FÜR ZUCKERRÜBENFORSCHUNG, GÖTTINGEN

–––––––––––––– Additive ––––––––––––––Level OH- Ca2+ Lime Gypsum# Soda lye##

[mmol kg-1 DM] [g kg-1 DM] [t ha-1] [g kg-1 DM] [t ha-1] [ml kg-1 DM]

Low 53.5 26.8 1.5 2.8 3.9 7.3 54Med 142.7 71.3 4.0 7.5 10.4 19.4High 285.3 142.7 8.0 15.0 20.7 38.8

# Gypsum as hemihydrate (β CaSO4 · 0.5 H2O); ## 1 molar; DM = dry matter

Fig. 1: Effect of additives given in low, medium and high level to the soil on plant P uptake and content, soilextractable P (CAT, CAL, EUF – fraction F1 & F2), and pH and EUF Ca content [mg (100 g)-1]. Means of 2 soilsand 3 incubations. Means with the same letter within each row are not significantly different at p ≤ 0.001.

• The effect of the site on the parameters was significant, while incubation time had no effect; relevant interactions between additive, site

and incubation time did not occur (not shown)

• The addition of Lime and Soda lye increased the pH from 6.9 (Control) up to 8.9 (LimeHigh), while Gypsum had no pH effect (Fig. 1)

replicates; soils were incubated (24, 8, 4 weeks, 12 °C, 40% WHCmax)

• Greenhouse trial: 5 sugar beet plants were grown in pots filled with

1 kg of the incubated soils for 10 weeks at 18 °C and 80% WHCmax

• Analyses: (1) Soil: pH; Electro-Ultrafiltration- (EUF-), CAL- and CAT-

(CaCl2 + DTPA) extraction; (2) Plant: total yield; P content & P uptake

(indicating plant available P)

• LimeMed,High, GypsumLow,Med,High and Soda lye

increased the plant yield compared with

the control by 60%, 60% and 191%,

respectively (not shown)

• Plant P content and P uptake increased

with increasing amounts of lime, but

remained constant in Gypsum treatments.

Soda lye addition caused the highest P

uptake (Fig. 1)

• The addition of Lime & Soda lye increased

the soil P extractable by EUF (except

LimeHigh) & CAL (LimeMed,High) (Fig. 1)

• The soil extraction methods detected con-

siderably (CAL) and slightly (EUF) more P

than the plants were able to take up (Fig. 1)

• The correlation between P extracted from

the soil and plant P uptake was close

(EUF: r = 0.79; CAL: r = 0.78; not shown)

• CAT extractable P exhibited a close

correlation to the plant P uptake only in

Gypsum treatments (rGypsum = 0.91).