Prospects and problems of Conservation Agriculture in Semi arid Tropics

2. What is Conservation Agriculture?
An array of technologies such as
residue retention, zero- and
reduced tillage, crop rotations,
green manure cover crops,
controlled traffic and raised
beds. When used in combination
these, over time, reduce, and
often revert, the degradation of
soil and water resources.
Residue retention distinguishes
conservation agriculture from
conventional agriculture, and all
conservation systems include at
least a certain level of surface
residue cover.

3. Goals of CA
FAO defined goals of CA as follows:
“CA aims to conserve, improve, and make more efficient use of
natural resources through integrated management of available soil,
water, and biological resources combined with external inputs. It
contributes to the environmental conservation as well as to the
enhanced and sustained agricultural production. Therefore, it can
also be referred to as resource efficient or resource effective
agriculture”.

5. WORLD SCENARIO
In India it is being practiced about 2-3 mha (WCCA Report 2009).

6. BASIC PRINCIPLES OF CA
 Minimal Soil disturbances
enable through No-till/reduced
tillage
 Maximum soil cover/
residues
 Appropriate crop sequences/
rotations (Spatial and temporal
crop sequencing).

7. Conservation Agriculture Means Dramatic
Tillage Reductions Combined with Adequate
Surface Retention of Crop Residues
Conventional Till Systems CA Zero Till Systems

8. Zero Till (ZT) –Wheat Seeding
• Reduced costs (Rs 2000-2500/ha)
due to savings in fuel and labor
• Timely planting of kharif and
winter season crops, resulting in
higher yields
• Lower density of herbicide
resistance in comparison to
traditional tillage.
• Significant irrigation water
savings (up to 15-20%)
• Improved input use efficiency
because of the right placement of
seed and fertilizer nutrients
• Better plant stands
• Less burning of crop resides
Advantages of Zero Tillage

9. Resource Conserving Technologies (RCTs)
1. No-tillage
2. Laser land leveling
3. Direct seeding of rice
4. Leaf colour chart for N
5. Crop diversification
Conventional RCTs

10. CA based RCTs options for System
sustainability
Zero tillage
Paired row ZT
Control traffic ZT
Direct seeding
Unpuddled transplanting
Reduced tillage
Bed planting
Surface seeding

11. SEMI-ARID TROPICS
Characterized by:
• variable and unpredictable rainfall
• structurally unstable soils
• low overall productivity

12. CONSERVATION AGRICULTURE IN
SEMI –ARID TROPICS
 protects the soil from the heating effect of the sun
 protect soil against raindrop impact
 allow improvement in soil aggregation
 practices of minimum/ zero tillage and direct sowing
techniques lead to minimum disturbance of soil.

13. Properly Managed CA Encourages
Sustainable Soil Management
Physical
Soil Quality
Chemical
Soil Quality
Biological
Soil Quality
Soil
Organic
Matter

14. Soil Chemical Quality:
 Higher soil cation exchange capacity (CEC) due to
increased organic matter content.
Systems with pigeon peas (Cajanus cajan) resulted in a 70%
increase in CEC compared to a fallow-maize system
(FAO, 2001).
Combination of ZT with sufficient crop residue retention
reduces evaporation from the topsoil and salt accumulation
(Hobbs and Govaerts, 2010).

15. Contd.
Table : Organic Carbon in Conventional & Minimum tilled fields
Tillage Treatments Organic C (g/kg)
0 – 5 cm 5-20 cm
Conventional
Tillage
5.42 5.26
Minimum Tillage 6.16 6.00
Improves soil organic Carbon

16. Soil Physical Quality
Table:Tillage and Nitrogen level
effect on infiltrability (cm/hr) Reduce soil
compaction
due to reduced traffic
and application of crop
residues.
 Increase infiltration
rate of water
Tillage N50% N100
%
N150% Averag
e
CT-CT 3.02 2.84 1.08 2.31
MB-RT 2.96 7.53 8.61 6.37
RT-RT 2.85 8.88 6.24 5.99
NT-NT 3.04 10.91 11.05 8.33
Average 2.97 7.54 6.74

17. Contd..
Increase soil moisture percentage

18. Conservation
Agriculture
enhances
biological
tillage
instead of
mechanical
tillage

19. Effect of Tillage on Soil Rhizobium Populations
0
10
20
30
40
50
60
Zero Tillage Conventional Tillage
Rhizobiumcells
Voss and Sidiras, 1985

20. Conservation Agriculture and C sequestration
Differences in soil organic carbon content (%) due to
adoption of zero-tillage over conventional tillage.

21. Conservation and Water Use Efficiency
 CA improve rain water infiltration (Shaxson et al., 2008)
 Improve water holding capacity (Govaerts et al., 2009)
 Reduce evaporative loss of water(Scopel et al., 2004)

22. Conservation Agriculture and Climate Change- Mitigation and
Adaptation:
Adaptation to climate change mainly due
to enhanced water balance
 Climate change mitigation through possible C
sequestration and reduced emission of CO2 to the
atmosphere

23. Conservation Agriculture and Climate Change- Mitigation and Adaptation
Figure : Mitigation and adaptation to climate change and variabilities through CA (Lal,2010)

24. Why CA is difficult to adopt?
 Mindset/ attitudinal change
 Strategies different from those we have adopted over past
decades
 Non-availability suitable farm equipment/ Farmers’ choice.

25. Constraints in Scaling Up Conservation Agriculture in SAT
 Competitive Uses of Crop Residues
 Weed Preponderance
 New Implements and Operating Skills Required
 Nutrient Immobilization
 Carryover of Insect-Pests and Disease Pathogens

26. Monoculture leads to a build-up of
pests and diseases. This is far more
marked in zero tillage than in
conventional tillage
The key to controlling pests and diseases
in zero tillage agriculture is crop
rotation. One should avoid seeding a
crop into it’s own residues before these
are decomposed.

27. Up Scaling Conservation Agriculture in SAT
The obstacles in up scaling CA can be overcome
through:
Interaction among associations of interested people
organization of promotional events such as field days
By providing credit to farmers to buy the equipment,
machinery, and inputs through banks and credit
agencies at reasonable interest rates.

28. Concluding Remarks:
 The SAT is characterized by highly variable and low
rainfall, poorly developed infrastructure, degraded soils, and
low socio-economic condition of the farmers.
 CA has been reported as sustainable and eco-friendly
crop production technique in the fragile eco-systems of SAT.
In the long-term CA has been found to render several
benefits including
 soil conservation with improved soil health
 higher rain water use efficiency
 climate change mitigation and adaptation
 improved biodiversity
higher economic returns