crop roots and crop residues management: impacts on soil structure under zero tillage. mariela...

Mariela Fuentes, Paola Solís, Fernando De León, Carmen Gutiérrez, Bram Govaerts

CROP ROOTS AND CROP RESIDUES MANAGEMENT: IMPACTS ON SOIL STRUCTURE UNDER ZERO TILLAGE

*Soil physical quality

*Aggregation

*Pore systems

Conventional tillage Zero tillage

with without with withoutresidues residues residues residues

rotation maize-wheat,wheat-maize monoculture (maize and wheat)

EXPERIMENTAL STATION OF “EL BATÁN” CIMMYT

ZTM+r / -rZTR+r / -r

CTM+r / -rCTR+r /-r

*The experiment was set up in 1991

*Subtropical highlands of central Mexico

*Haplic Phaeozem

25% sand 37% silt and 38% clay

-2

-1

0

1

2ZTM+r

ZTM-r

ZTR+r

ZTR-r

CTM+r

CTM-r

CTR+r

CTR-r

YieldsPC1 (C,N,Ag,H)

PC2 (H,-RP,pH)

MAIZE

-2

-1

0

1

2ZTM+r

ZTM-r

ZTR+r

ZTR-r

CTM+r

CTM-r

CTR+r

CTR-r

YieldsPC1 (SOM, Moist., Ag.)

PC2 (pH, CE, Resist Penet, P)

WHEAT

0

10

20

30

40

50

60

70

ZTR+r ZTM+r CTR+r CTM+r ZTR-r ZTM-r CTR-r CTM-r

Agg

rega

tes

dist

ribu

tion

(%)

0

0.4

0.8

1.2

1.6

2

Mea

n W

eigh

t Dia

met

er (

mm

)

0

10

20

30

40

50

60

70

ZTR+r ZTM+r CTR+r CTM+r ZTR-r ZTM-r CTR-r CTM-r

Agg

rega

tes

dist

ribu

tion

(%)

0

0.4

0.8

1.2

1.6

2

Mea

n W

eigh

t Dia

met

er (m

m)

Ag

gre

gat

es

dis

trib

uti

on

(%

)

Mea

n w

eig

th d

iam

met

er (

mm

)

0 to 5 cm 5 to 10 cm

WHEAT

AGGREGATES

Aggregates 1-8mm

Aggregates 0.25-1mm

Aggregates <0.25 mm

Evaluated the influence of two root systems (maize andwheat) and crop residues management on the soil pore system in different agriculture management

ZTM-r ZTM+r ZTR+r

0–5, 5-10, 10-15 and 15-20 cm depth2 samples for plot

TOTAL POROSITY

COMPOUND PACKING VOIDS

BIOPORES

FISSURES

Thin sections were processed Image-Pro®statistical analysis: linear model and analysis of variance

0

10

20

30

40

50

60

70

ZTMm-r ZTMw-r ZTMm+r ZTMw+r ZTRm+r ZTRw+r

Tot

al s

oil p

oros

ity

(%)

0 to 5 cm LSD 7.65 to 10 cm LSD 6.210 to 15 cm LSD 5.4 15 to 20 cm LSD 5.7

ZTR+r ZTMw+r ZTMm+r ZTMm-r

0–5 cm

5-10cm

10-15 cm

15-20 cm

Thin sections

channels or bioporescompound packing voids, fissures

0 a 5cm

0

10

20

30

40

50

60

70

ZTMm-r ZTMw-r ZTMm+r ZTMw+r ZTRm+r ZTRw+r

cm 1

00 m

-2

5-10cm

0

10

20

30

40

ZTMm-r ZTMw-r ZTMm+r ZTMw+r ZTRm+r ZTRw+r

cm 1

00 c

m-2

10-15 cm

0

5

10

15

20

25

ZTMm-r ZTMw-r ZTMm+r ZTMw+r ZTRm+r ZTRw+r

cm 1

00 c

m-2

15-20 cm

0

5

10

15

20

25

ZTMm-r ZTMw-r ZTMm+r ZTMw+r ZTRm+r ZTRw+r

cm 1

00cm

-2

Monoculture vs rotation

The root wheat-soil relation favors the formation of pores

The roots per se do not generate a fully satisfactory soil structure; it is necessary to keep crop residues at the soil surface.

Conservation agriculture improves soil porosity (crop rotations)

CONCLUSION

Thank you very much

We know more about the movement of the celestial bodies than about the soil underfoot

Da vinci