A presentation made at the WCCA 2011 event in Brisbane, Australia.

1. CROP ROOTS AND CROP RESIDUES
MANAGEMENT: IMPACTS ON SOIL
STRUCTURE UNDER ZERO TILLAGE
Mariela Fuentes, Paola Solís, Fernando De León,
Carmen Gutiérrez, Bram Govaerts

2. *Soil physical quality
*Aggregation
*Pore systems

3. EXPERIMENTAL STATION OF “EL BATÁN”
ZTM+r / -r
CIMMYT
ZTR+r / -r
Conventional tillage Zero tillage
CTM+r / -r
with
CTR+r /-r
without with without
residues residues residues residues
*The experiment was set up in 1991
*Subtropical highlands of central Mexico
*Haplic Phaeozem
rotation maize-wheat,wheat-maize
25% sand 37% silt andand wheat)
monoculture (maize 38% clay

4. MAIZE ZTM+r
2
CTR-r 1 ZTM-r
0
-1
CTR+r -2 ZTR+r
Yields
PC1 (C,N,Ag,H)
PC2 (H,-RP,pH)
CTM-r ZTR-r
CTM+r

5. WHEAT ZTM+r
2
CTR-r 1 ZTM-r
0
-1
CTR+r -2 ZTR+r
CTM-r ZTR-r
Yields
PC1 (SOM, Moist., Ag.) CTM+r
PC2 (pH, CE, Resist Penet, P)

6. AGGREGATES
WHEAT
Aggregates 1-8mm0 to 0.18)
(LSD 5 cm Aggregates 0.25-1mm (LSD 0.14)
2 Aggregates 1-8mm (LSD 0.23)
5 to 10 cm 0.25-1mm (LSD 0.08) 2
Aggregates
Aggregates <0.25 mm (LSD 0.18)
Aggregates <0.25 mm (LSD 0.14)
70 70
MeanMean Weight Diameter (mm)(mm)
Aggregates distribution (%)
Mean Weight Diameter (mm)
1.6 1.6
60
Aggregates distribution (%)
60
weigth diammeter
Aggregates distribution (%)
50 50
1.2 1.2
40 40
30 0.8 0.8
30
20 20
0.4 0.4
10 10
0 0
0 0
ZTR+r ZTM+r CTR+r CTM+r ZTR-r ZTM-r CTR-r CTM-r ZTR+r ZTM+r CTR+r CTM+r ZTR-r ZTM-r CTR-r CTM-r
Aggregates 1-8mm
Aggregates 0.25-1mm
Aggregates <0.25 mm

7. Evaluated the influence of two root systems (maize and
wheat) and crop residues management on the soil pore system in
different agriculture management
ZTM-r ZTM+r ZTR+r

8. 0–5, 5-10, 10-15 and 15-20 cm depth
2 samples for plot

9. TOTAL POROSITY
COMPOUND PACKING VOIDS
BIOPORES
FISSURES
Thin sections were processed Image-Pro®
statistical analysis: linear model and analysis of
variance

10. 70 0 to 5 cm LSD 7.6
5 to 10 cm LSD 6.2
Total soil porosity (%)
60 10 to 15 cm LSD 5.4
15 to 20 cm LSD 5.7
50
40
30
20
10
0
ZTMm-r ZTMw-r ZTMm+r ZTMw+r ZTRm+r ZTRw+r

11. Thin sections
ZTR+r ZTMw+r ZTMm+r ZTMm-r
0–5 cm
5-10cm
10-15 cm
15-20 cm

12. channels or biopores
compound packing voids,
fissures
70
0 a 5cm 40 5-10cm
60
50 30
cm 100 cm-2
cm 100 m-2
40
30 20
20
10
10
0 0
ZTMm-r ZTMw-r ZTMm+r ZTMw+r ZTRm+r ZTRw+r ZTMm-r ZTMw-r ZTMm+r ZTMw+r ZTRm+r ZTRw+r
15-20 cm
25 10-15 cm
25
cm 100 cm-2
20
20
cm 100cm-2
15 15
10 10
5 5
0 0
ZTMm-r ZTMw-r ZTMm+r ZTMw+r ZTRm+r ZTRw+r ZTMm-r ZTMw-r ZTMm+r ZTMw+r ZTRm+r ZTRw+r
Monoculture vs rotation

13. CONCLUSION
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)

14. We know more about the
movement of the celestial
bodies than about the soil
underfoot
Da vinci
Thank you very much