University of Extremadura, Forestry School of

Plasencia

The role of trees for Nitrate leaching after Organic and

Mineral fertilization

ML López-Díaz, G Moreno, V Rolo

Introduction

Underground water

Agriculture

Nitrate leaching

Directive 80/788/CEE

Directive 91/676/CEE

Fertilization rate

Irrigation systems

Introduction

PROBLEM

Nitrate leaching

SOLUTION

Agroforestry Systems

OrganicFertilization

Tree – pasture root system Gradual N mineralization

LIXIVIATED NITRATE

Soil Nitrate

Pasture

Fertilization Treatments

Tree

Aims

Materials and Methods

Systems

D Bare soil P Pasture S TreeSP Tree & pasture

Fertilization

NF No fertilize L Sewage Sludge M Mineral

Greenhouse experimentn = 6

120 pots: 20 cm Ø, 120 cm heightSoil: pH 4.7; 1 g N kg-1; 10 g Organic C kg-1

Materials and Methods

1 2

3

4 5

Par

amet

ers

anal

yzed

Par

amet

ers

anal

yzed

Tree Basal Diameter Pasture Production

Nitrate LixiviatedProfile of Nitrate Content

Rooting profile

Results & Discussion

NO3- Content in the Soil Profile NO3

- Content in the Soil Profile

0

20

40

60

80

100

120

0 5 10 15

Pro

fun

did

ad,

cm

NO3-, mg/kg suelo

D

P

S

SP

NO3- , mg / Kg soil

Dep

th, c

m

Systems

D Bare soil P Pasture S TreeSP Tree & pasture

0

20

40

60

80

100

120

0 1 2 3 4 5 6

Pro

fun

did

ad,

cm

NO3-, mg/kg suelo

L

M

NF

Dep

th, c

m

NO3- , mg / Kg soil

Fertilization Treatments

NF No fertilize M Mineral L Sewage Sludge

Results & Discussion

Nitrate Lixiviation and Fertilization RatesNitrate Lixiviation and Fertilization Rates

0

20

40

60

80

100

120

14-12-05 24-3-06 2-7-06 10-10-06 18-1-07 28-4-07 6-8-07 14-11-07

Fecha

Nitr

ato

, g /

m2

NF

M30

M60

L30

L60

Fertilization

Nit

rate

, g /m

2

Fertilization Treatment

20062007

AÑO*ferdos; LS Means

Current effect: F(4, 100)=90,908, p=0,0000Effective hypothesis decomposition

Vertical bars denote 0,95 confidence intervals

AÑ0 2006 AÑO 2007

NF M1 M2 L1 L2

Tratamiento de ferti l izac ión

0

50

100

150

200

250

Nitr

ato,

g /

m2

Date

Nit

rate

, g /m

2

Fertilization Treatments

NF No fertilize M Mineral L Sewage Sludge

Nitrate Lixiviation and Systems Nitrate Lixiviation and Systems

Results & Discussion

AÑO*SIST; LS Means

Current effect: F(3, 100)=23,484, p=,00000Effective hypothesis decomposition

Vertical bars denote 0,95 confidence intervals

AÑO 2006 AÑO 2007

D P S SP

SISTEMA

0

50

100

150

200

250

Nitra

tos,

g /

m2

System

Nitr

ate,

g /m

2

20062007

0

10

20

30

40

50

60

70

80

14-12-05 24-3-06 2-7-06 10-10-06 18-1-07 28-4-07 6-8-07 14-11-07

Fecha

Nitr

ato,

g /

m2

D

P

S

SP

Fertilization

Date

Nit

rate

, g /m

2

Systems

D Bare soil P Pasture S TreeSP Tree & pasture

Results & Discussion

Root systemRoot system

Tree

Pasture

0

10

20

30

40

50

60

70

80

90

100

0 2 4 6 8 10 12

Dep

th, c

m

Root Surface Density, m2 m -3

Tree

Tree + Pasture

0

10

20

30

40

50

60

70

80

90

100

0 10 20 30 40 50 60

Dep

th, c

m

Root Surface Density, m2 m -3

Pasture

Pasture + Tree

Results & Discussion

ProductionProduction

0

1000

2000

3000

4000

P SP (Pasture)

Pas

ture

yie

ld, K

g ha

-1ye

ar-1

No significant differences

0

2

4

6

8

10

12

S SP (Tree)

Bas

al D

iam

eter

, mm

No significant differences

Conclusions

The use of agroforestry systems are a good tool to control the nitrate leaching adjusting properly the fertilization rate to minimize the competitive effect

between vegetation layers

The use of agroforestry systems are a good tool to control the nitrate leaching adjusting properly the fertilization rate to minimize the competitive effect

between vegetation layers

THANKS FOR YOUR ATTENTION

Victor Rolo