effect of crop rotation on soil fertility

1. Effect of crop rotation on soil properties' or fertility
Name: Siddique Ahmad
Class no. : 38
Presentation : effect of crop rotation on soil
properties/Fertility
SIDDIQUE AHMAD
CLASS NO: 38
PRESENTATION: EFFECT OF CROP ROTATION ON SOIL FERTILITY
DEPARTMENT OF AGRONOMY
AGRICULTURE UNIVERSITY OF PESHAWAR

2. Concept of crop rotation
 Crop rotation is the practice of growing different crops on the same piece of land
season after season or year after year in such a manner that soil fertility is
minimally disturbed and farmers output increased.
Benefits of crop rotation are :
 Maintenance of soil fertility
 Efficient utilization of farm resources
 Weeds control
 Disease and pest control
 Uniform distribution of labour
Principles of crop rotation :
 Crops of the same family should not follow each other in rotation ( wheat and maize ).
 Leguminous crops should be included in rotation every two to three years.
 Green manures and forages crop should also be included in rotation.

3.  Shallow rooted crops should fallow deep rooted crops.
 Crops susceptible to certain disease and insect should followed by crops which are
resistant to these disease and insects.
Difference between crop rotation and sequential cropping :
Both are practically same thing, there is little difference between these terms
 Crop rotation mean maintenance of soil fertility, controlling weeds and disease,
utilization of farm resources.
 Sequential cropping mean growing of two or more crops in sequence on the same field
per year without keeping the above objectives in mind.

4. Different terminologies
 Cropping system: minimize risk of the total crop failure, it is the practice of growing
crops on farm in interaction with farm resources, enterprises and technology
 Cropping pattern: yearly sequence and spatial arrangement of crops on a given area of
land in a particular agroecological zone. ( wheat maize wheat ) (tobacco maize wheat )
 Cropping scheme: theoretical chart showing different crops rotation to be used in a
farm during a given period of time usually one year.

5. What are the soil properties
To study the effect of crop rotation on soil, it is important to know the soil properties:
 Soil texture:
The proportion of various soil particles of various size. Sand silt and clay. It
effect soil porosity, water movement, gaseous exchange, water holding capacity etc.
 Soil structure:
The arrangement of soil particles.
 Soil porosity:
space which are not occupied by soil particles.
 Bulk density:
mass per unit volume of the dry soil including the pores space + solids.
 Soil pH:
-log of hydrogen ion concentration.

6. Introduction
 Soil organic matter and clay particles hold large stores of plantnutrients.
 These reservoirs, however, are not all available to thecrop.
 Crop rotation manages soil organic matter and nutrient availability by------
- incorporating different crop residues,
- cycling among crops with different nutrient needs,
- using cover crops, and
- adding soil amendments.

7. Introduction
• Most crops deplete soil nutrients during their growthcycle.
• Some of these nutrients leave the farm as harvested products, and the restreturn
to the soil as crop residues.
• The nutrients in residues may or may not be available to the nextcrop.
• Crop roots and residues improve soil fertility by
- stimulating soil microbial communities and
- improving soil aggregation.

8. Improves soil physical properties
• This improved soil physical environment facilitates
- water infiltration,
- water holding,
- aeration, and
- ultimately, root growth and plant nutrient foraging.
• Understanding thebasics of how nutrients are added to and released from soil
organic matter will help in choosing crop sequences and amendments to
optimizecropfertility.
• Toeffectively plan organic crop rotations tomeet
crop nutrient needs, severalfactorsshould be
considered.

9. Major approaches
1. Legume crops
- capture atmospheric nitrogen and ‘fix’it into forms available to plants
- can be used in rotations to meet the needs of nitrogen demandingcrops.
2. Cover crops used after cash crop
- capture surplus plant - available nutrients and conserve these forfollowing
crops.
3. Other amendments
- such as fertilizers and manures can supplement nutrients at targeted times
during the rotation.

10. Classical Example
An example of a successful rotation
Generate residues in the rotation
Generate cash income
Adds soil fertility

11. Crop Rotation with regard to Soil Fertility
 Crop Rotation plays a vital role in managing soil fertility in the followingaspects:
1. Soil erosion
2. Soil compaction
3. Infiltration
4. Soil crusting
5. Nutrient loss or imbalance
6. Pesticide carry over
7. Soil organic matter
8. Biological activity

12. Crop Rotation and Soil Erosion
 Vegetative cover has a major effect on erosion.
 Effective erosion control practices:
- Growing cover crops with low residue crops and
- Rotation of high residue crops with low residuecrops
• Crop rotations that utilize the land more intensively such as corn, wheat and
soybeans grown in two years produce larger amounts of biomass during the
rotation and are more effective in reducing erosion than a continuous cropping
sequence (Heath et al 1976).

13. Crop Rotation and Deposition of Sediment
• Increase cover from grass and or legume rotations or high residuecrops
combined with other conservation practices such as ---
- conservation tillage will reduce upland erosion which inturn,
- reduces sediment from surface runoff and wind.
Soil Aggregation at the Surface ( anything at the surface )
Rotations that promote the increase of organic matter andmicrobial
activity will increase aggregate stability.
[Caution: If residue is incorporated, with tillage, benefits of increased biomassis
lessened.]

14. Crop Rotation and Soil Compaction
• Monoculture agriculture and tillage weaken soil structural characteristics
increasing susceptibility to compaction (Schnitzer 1991).
• Crop rotations with deep root systems can reduce compaction through the
addition of organic matter and development of channels from decayedroots;
thus improving water movement and aeration.
• Rotations that increase organic matter, microbial activity and aggregation of soil
particles, will also increase porosity and lower bulk density

15. Crop Rotation and Infiltration
• Conservation crop rotation systems that promote an increase in organic matter
and an increase of aggregate stability will maintain or improve the presenceof
pores for infiltration (Schnitzer, 1991).
• Decaying roots, especially those of deep rooted crops like alfalfa and will
leave channels for improved infiltration.
• Other conservation practices may be needed in crop rotations such as crop
residue management to ensure surface protection and improve infiltration.
[Caution: Macropores can result in an increase of leaching of highlysoluble
pesticides if a heavy rain occurs within a few hours after application.]

16. Crop Rotation and Soil Crusting
• If residues are left on the soil surface and crop rotations are included withhigh
residue crops,
- the increase in organic matter,
- improved infiltration, and
- increased aggregate stability --- will reduce soilcrusting.
[Caution: Monoculture and low residue cropping systems with tillage will
increase the decay of organic matter and reduce aggregate stability which often
results in soil crusting]

17. Crop Rotation and Nutrient imbalance
 One of the principles of crop rotation is to precede a nitrogen demandingcrop
with a legume crop to provide nitrogen.
 Crop rotations with deeply rooted crops can penetrate to depths of 5 to 6 feetand
‘cycle nutrients’ especially the more soluble nutrients such asnitrates.
 Crop rotations that promote increased biomass provide a slow release of
nutrients to the root zone.

18. Crop Rotation and Pesticide carry over
 Where different crops are grown each year and crop rotations reduce thechance
of pesticide build-up.
 The threat of pest tolerance to insecticides and herbicides are reducedwith
rotations (Reeves, 1994).
 Rotations increasing organic matter improve the environment for biological
activity that will increase the breakdown of pesticides.

19. Crop Rotation and Soil Organic Matter
 The amount and type of organic matter is indicative of soilproductivity
(Mitchell et al 1996).
 The types of crops grown, the amounts of roots, biomass yield, and efficiencyof
harvest, and the management of residues affect soil organic matter (Magdoff,
1993).
 It is practically impossible to increase organic matter where mouldboard
ploughing is taking place. (Reicosky et al, 1995).
 Vegetables and other low residue crop rotations will need other practices suchas,
cover crops to increase biomass yield.

20. Crop Rotation and BiologicalActivity
 There is a direct relationship to the amount of residue and the population ofsoil
microorganisms.
 Research in Oregon showed wheat-fallow systems had only 25% ofthe
microorganisms found under pasture.
 When rotations are more complex and include rotational crops soil biological
diversity will increase (Magdoff, 1993).
 Soil organisms that are active in the soil, include bacteria, fungi, actinomycetes,
protozoa, yeast, algae, earthworms and insects.
 Numbers of soil organisms in general are proportional to organicmatter
concentrations in the upper 15 inches (Schnitzer,1991).

21. Vegetables – nutrient availability
Ranking of annual vegetables based on nutrientrequirements
Low Medium High
Beans, all Brassica greens Broccoli
Beet Cucumber Cabbage
Carrot Eggplant Cauliflower
Herbs Pepper Corn
Peas Pumpkin Lettuce
Radish Spinach,chard Potato
Squash Tomato
Sweet Potato
Watermelon
Winter squash
Note: Vegetables are classified as having low, medium, or high
nutrient requirements. These categories do not account for
differences among varieties.

22. Cost benefits of crop rotation
How much does it cost:
There is little to no cost to implement this practice.
Financial benefits:
 Reduced fertilizer inputs
 Reduced pesticide inputs

23. Crop Rotation planning considerations
Identify soil erosion, nutrient, and soil healthconcerns
Soil test (every 1-3 years) for pH, organic matter and
nutrients. Use soil test recommendations to adjustpH
and nutrient levels for optimum crop yields and
quality
Determine nutrient (fertilizer manure orcomposts)
needs

24. Crop Rotation planning considerations
Choose the crops/varieties to meet the erosion,soil
health, nutrient concerns
Evaluate and modify the crop sequence based on the
identified concerns.
Evaluate cover crop needs
Clean field equipment when moving from one field to
another. Wash with water and/or physically remove
the soil and plant residue from the equipment

25. Practical applications
 Using a map, lay out a rotation for
the crops by year for the length of the
rotation.
 Plan the rotation for the operation to
establish a nearly equal acreage of
each crop each year.
Example 4 year crop rotation:
Corn – Oats – Hay – Hay

26. Crop Rotation maintenance
1. Periodic soil testing (initially every 1-3 years, then later at 3-5 years).
2. Crop and pest scouting.
3. Annually, evaluate cropping sequence for income needs and soil concerns.
4. Calibrate sprayers, planters and fertilizer applicatorsto:
 Apply the recommended rates.
 Establish uniform distributions
 Provide uniform seeding depths

27. Some tips on Crop Rotation

28. Some tips on Crop Rotation

29. Some tips on Crop Rotation

30. Some tips on Crop Rotation

31. References
Websites :
1. http://www.sare.org/Learning-Center/Books/Crop-Rotation-on-Organic-
Farms/Text-Version/Physical-and-Biological-Processes-In-Crop-
Production/Crop-Rotation-Effects-on-Soil-Fertility-and-Plant-Nutrition
2. http://people.oregonstate.edu/~muirp/sustfert.htm
3. http://soilquality.org/practices/row_crop_rotations.html
Books
1. John L. Havlin, Samuel L. Tisdale, Werner L. Nelson, James D. Beaton, Soil
Fertility and Fertilizers an introduction to nutrient management.