1. Mitigation of water erosion in MediterraneanMitigation of water erosion in Mediterranean
climatic zone of central Chile : effects of noclimatic zone of central Chile : effects of no
tillage systems and others soil conservationtillage systems and others soil conservation
practicespractices
Ingrid Martínez, Christian Prat, Carlos Ovalle, Erick Zagal, Neal Stolpe,
Alejandro del Pozo, Hamil Uribe
Landcom, October 2010

2. Mitigation of water erosion inMitigation of water erosion in
Mediterranean climatic zone of centralMediterranean climatic zone of central
ChileChile
On behalf of my colleaguesOn behalf of my colleagues

3. MEDITERRANEAN
CENTRAL - CHILE
Rainfall mm per yr
0-50 mm
100-300
400-500
600-800
800-1000
>1000
Rainfall
Temperature

4. GGeomorphologieeomorphologie of Central Chile ( at 36° LS)of Central Chile ( at 36° LS)

5. Low crop yield andLow crop yield and pasturepasture productiproductivityvity
LLowow animal stocking rateanimal stocking rate
Low profitability of theLow profitability of the farms (farms (cereal and meat productioncereal and meat production))
Crop (yr 2)Crop (yr 2)
Unsown pasture (yr 3)Unsown pasture (yr 3)
Fallow (yr 1)Fallow (yr 1)
The land use systemThe land use system

6. Precipitación
Evaporación
En Fe Mar Ab May Jun Jul Ag Se Oc No Di
0
50
100
150
200
250
Precipitación-Evaporación(mm)
(a)
Título
Precipitación
Evaporación
Concentrated period of
rainfall and intensity of
the events
Unstable fragile Granitic soils
What causes soil erosion in Chile?
Traditional Tillage
practices( With iron-
tipped plow reversing soil)
Steep slopes

7. But at the heart of the problem is the man.
Indeed, the small farmer is required to plow the
land, because on it depends their livelihood and
the support of his family

8. Objectives
• To asses the effects of Soil Conservation Tillage Systems on:
•Runoff
•Soil and nutrient losses
•Soil compaction
•Temporal and spatial variation of Soil Water Content
(SWC) in the soil profile
•Yield and phenological development of the crops
In Chile, like in others parts of the world, impropriated agricultural practices had
contributed to accelerate soil degradation. Soils are highly affected by water erosion, so
New tillage systems can be TESTED to improve soil physical and chemical properties
and to mitigate water erosion

9. METHODOLOGY

10. Horizons Sand Loam Clay
Texture
Bulk
density Total porosity
cm % % % (Mg m3
) %
0-18 72,6 12,6 14,8 Sandy loam 1,79 28,4
18-36 42,4 13,0 44,5 Clay 1,69 32,4
36-61 34,2 17,6 48,2 Clay 1,75 30,0
61-100 32,2 19,6 48,2 Clay 1,77 29,2
Soil characteristics
Very lowVery low
porosityporosity
Very lowVery low
porosityporosity
•Soil is an entisol, classified as a Mollic Palexeralfs (CIREN, 1994)
•Low organic matter content , (<1,5%) and
and macronutrient (N - P and S)
•Soil is an entisol, classified as a Mollic Palexeralfs (CIREN, 1994)
•Low organic matter content , (<1,5%) and
and macronutrient (N - P and S)

11. • Characteristics of rainfalls
• 695 mm mean annual
• Strong concentration in autumn and winter
• Very intensive events of rain
0
50
100
150
200
250
300
350
400
Jan Feb Mar Apr May Jun Jul Aug Sept Oct Nov Dec
Month
mm
2007 (372mm)
2008 (768mm)
2009 (536mm)
x 44 years (695 mm)
Precipitación
Evaporación
En Fe Mar Ab May Jun Jul Ag Se Oc No Di
0
50
100
150
200
250
Precipitación-Evaporación(mm)
(a)
Título
Precipitación
Evaporación

12. Plot size 1000m2
(20mx50m)
Crop rotation from 2007 to 2009:
Oat (Avena sativa cv. Supernova-INIA) – wheat (Triticum aestivum L cv Pandora-INIA)
Sowing date: May in each year
Plot size 1000m2
(20mx50m)
Crop rotation from 2007 to 2009:
Oat (Avena sativa cv. Supernova-INIA) – wheat (Triticum aestivum L cv Pandora-INIA)
Sowing date: May in each year
Experimental Site description

13. NO TILLAGE NT + CONTOUR
PLOUGHING
NT + BARRIER
HEDGES
NT +
SUBSOILING
CONVENTIONAL
TITLLAGE
50 m
20 m
12,5 m
Treatments

14. Runoff rate: the water level was measured in each
holding tank (1m3
each one) after every rainfall event
Runoff rate: the water level was measured in each
holding tank (1m3
each one) after every rainfall event
Evaluations in crops
Monitoring on each season
Soil losses and nutrient losses: samples of 100ml were taken from the holding
tank and sediments were evaluated.
Soil losses and nutrient losses: samples of 100ml were taken from the holding
tank and sediments were evaluated.
Soil evaluations
Grain yield and BiomassGrain yield and Biomass
Rainfall were measured in a pluviometer installed in the study siteRainfall were measured in a pluviometer installed in the study site
Evaluations season 2007 to 2009

15. •Soil description in the profile: texture, bulk density, total porosity
•Soil compaction was evaluated with a conical tip penetrometer (Field
Scout SC900) 2,5 to 20 cm depth (each 2,5cm)
•Soil description in the profile: texture, bulk density, total porosity
•Soil compaction was evaluated with a conical tip penetrometer (Field
Scout SC900) 2,5 to 20 cm depth (each 2,5cm)
Soil evaluations
Monitoring soil water content (SWC)
•Neutron probe (Troxler, 4300 USA)
10-30, 30-50, 50-70, 70-90, 90-110 cm depth every 7 to 15 days
During rainy season (August to December), and tensiometers
•A pluviometer was installed in 2007 to register rainfall events (1 sec)
•Neutron probe (Troxler, 4300 USA)
10-30, 30-50, 50-70, 70-90, 90-110 cm depth every 7 to 15 days
During rainy season (August to December), and tensiometers
•A pluviometer was installed in 2007 to register rainfall events (1 sec)
Evaluations season 2007 to 2009

16. Map of experimental site ≈15% slope
No tillage (Nt) No tillage +
contour ploughing
(Nt+Cp)
No tillage +
barrier hedges
(Nt+Bh)
No tillage +
subsoiling
(Nt+Sb)
Conventional tillage
(Ct)
50 m
20 m
12,5 m
Tillage direction
slope
Acces tube location

17. Statistical analysis
•Soil water content was assessed using split-split-splot design
SAS software program and Tukey test was use to compare means
of significant values (p≤0,05)
-Tillage system (main plot)
-Monitoring date (split-plot)
-Soil depth (split-split-splot)
•Soil water content was assessed using split-split-splot design
SAS software program and Tukey test was use to compare means
of significant values (p≤0,05)
-Tillage system (main plot)
-Monitoring date (split-plot)
-Soil depth (split-split-splot)

18. RESULTS

19. Soil losses season 2008
Ct Nt Nt+Cp Nt+Bh Nt+Sb
Tillage system
0
25
50
75
100
(%)
%
Percentaje of soil losses in Ct and No tillage tillage system.
Conservation tillage systems lossed less than 25% compared to Ct.
%
Percentaje of soil losses in Ct and No tillage tillage system.
Conservation tillage systems lossed less than 25% compared to Ct.

20. Lt
Cl+Sb
Cl+Fv
Cl+Cd
Cl
J un J ul Aug
Season 2007
0
10
20
30
40
50
60
70
(%)
59 123 63 (mm)
Runoff
Lt
Cl+Sb
Cl+Fv
Cl+Cd
Cl
Ct
Nt+Sb
Nt+Bh
Nt+Cp
Nt
Jun Jul Aug Sep
Season 2008
0
10
20
30
40
50
60
70
(%)
103 102 94 22 (mm)
Runoff
Ct
Nt+Sb
Nt+Bh
Nt+Cp
Nt
Jun Jul Aug Sep
Season 2009
0
10
20
30
40
50
60
70
(%)
61 148 38 (mm)197
0
50
100
150
200
250
300
350
400
Jan Feb Mar Apr May Jun Jul Aug Sept Oct Nov Dec
Monthmm
2007 (372mm)
2008 (768mm)
2009 (536mm)
x 44 years (695 mm)
Monthly runoff
2007 2009
2008

21. Total nitrogen
0,0
0,5
1,0
1,5
2,0
2,5
01-jun 16-jun 01-jul 16-jul 31-jul 15-ago 30-ago
Season 2008
Ca
0,0
1,0
2,0
3,0
4,0
01-jun 16-jun 01-jul 16-jul 31-jul 15-ago 30-ago
Season 2008
Mg+2
0,0
0,5
1,0
1,5
01-jun 16-jun 01-jul 16-jul 31-jul 15-ago 30-ago
Season 2008
Ct
Soil nutrient losses in Conventional tillage compared to Conservation
tillage systems during season 2008
Ct
Ct

22. Nt Nt+Cp Nt+Bh Nt+Sb Ct
Tillage systems
0.0
0.6
1.2
1.8
2.4
3.0
Mgha-1
Oat crop yield during season 2008
No tillage with subsoiling (Nt+Sb) showed a higher productivity in driest year
compared with the rest of treatments.
No tillage with subsoiling (Nt+Sb) showed a higher productivity in driest year
compared with the rest of treatments.

23. 2007 Oat
2008 Wheat
2009 Oat
Ct Nt+Sb Nt+Bh Nt+Cp Nt
Tillage systems
0,0
1,0
2,0
3,0
4,0
5,0
Mgha-1
2007 Oat
2008 Wheat
2009 Oat
Grain yield oat-wheat crop rotation
season 2007-2009
•In season 2007, grain yield in Nt+Sb was significantly higher (p<0,01) to the
other treatments. Seasons 2007 to 2009, Nt and Nt+Cp obtained the lowest
grain yield.
•In season 2007, grain yield in Nt+Sb was significantly higher (p<0,01) to the
other treatments. Seasons 2007 to 2009, Nt and Nt+Cp obtained the lowest
grain yield.
2007200720072007

24. 10-30cm
30-50cm
50-70cm
4/09 15/09 23/09 2/10 7/10 22/10 20/11 18/12
Season 2008
10
20
30
40
50
60
70 Ct 10-30cm
30-50cm
50-70cm
4/09 15/09 23/09 2/10 7/10 22/10 20/11 18/12
Season 2008
10
20
30
40
50
60
70
Nt+Sb
4/09 15/09 23/09 2/10 7/10 22/10 20/11 18/12
Season 2008
10
20
30
40
50
60
70 Nt+Bh
Soil water content (SWC)
•Tillage systems, time and depth significantly influenced SWC (p<0,05).
•In general, under NT systems SWC was greater than under CT.
•Nt+Sb in the 10-30cm showed a rapid superficial drying, but a significant increment of SWC in depth.
•At the end of evaluations Ct, SWC decreased in 60% while No tillage systems decreased in 44 to 51%
•Tillage systems, time and depth significantly influenced SWC (p<0,05).
•In general, under NT systems SWC was greater than under CT.
•Nt+Sb in the 10-30cm showed a rapid superficial drying, but a significant increment of SWC in depth.
•At the end of evaluations Ct, SWC decreased in 60% while No tillage systems decreased in 44 to 51%
No tillage systemsNo tillage systems
Conventional tillageConventional tillage
4/09 15/09 23/09 2/10 7/10 22/10 20/11 18/12
Season 2008
10
20
30
40
50
60
70
Nt+Cp
4/09 15/09 23/09 2/10 7/10 22/10 20/11 18/12
Season 2008
10
20
30
40
50
60
70
Nt

25. Soil compaction
•Soils showed a severe compaction (>2000 kPa) at 12,5cm depth, except
Nt+Subsoiling, showing positive the effect for crops of subsoiling.
•Soils showed a severe compaction (>2000 kPa) at 12,5cm depth, except
Nt+Subsoiling, showing positive the effect for crops of subsoiling.
0
2.5
5
7.5
10
12.5
15
17.5
20
0 500 1000 1500 2000 2500 3000 3500 4000
Cone index (Kpa)
Depth(cm)
Ct
Nt+Sb
Nt+Bh
Nt+Cp
Nt

26. Main conclusions
• No tillage systems reduced soil losses in 75% compared to Ct.
• Runoff and soil losses was strongly associated to the high-intensity rainfall. The
percentage of runoff in relation to the rainfall was between 60-70% in Conventional tillage
(CT), while in No tillage was between 20-30% in the first month and less than 7% the
following months of the rain season.
• The loss of macronutrients were reduced in :
Nitrogen (<34%), Ca (<24%) and Mg (<20%) when we compare the Ct with conservation
tillage systems.

27. •Results demonstrated that No tillage systems incremented SWC in deep (50-
110 cm depth) increasing water infiltration compared to CT.
All cropping systems showed a severe soil compaction at 12,5cm depth
(>2000 kPa) except in NT+SB (≈1500 kPa), between 2,5-20cm depth and a
higher yield specially in driest year (2007)
•Finally, the choice of conservation tillage system without any modification
on soil structure will affect crop yield in compacted soils.
MAIN CONCLUSIONS

28. Runoff
Ct: 70%
No till: <30% the first month
<10% rest of rainfall
Conservation tillage
systemSoil losses
No tillage systems
reduced >75%
Nutrient losses
In No tillage compared to CT
N: <34%
Ca: <24%
Mg: <20%
Yield
Nt+Sb > 36% to Ct
DECREASE
INCREMENT
Water
availability for
crops
(Nt+ subsoiling)
Mitigation of
water erosion
process
Main conclusions
Nt+Sb Ct
Nt+Sb Ct

29. Soil water
content (SWC)
Soil water
content (SWC)
PHYSICAL INDICATORS AFFECTED CROP
PRODUCTIVITY
Soil water
infiltration
Soil water
infiltration
Soil
Compaction
Soil
Compaction
Yield

31. MUCHAS
GRACIAS