What is Crop Rotation?
Crop rotation is the practice of planting a sequence of different crops on the same plot of land. Crop rotation is important to help land sustain a lasting productivity. It sustain nutrients in the soil, interrupts stagnant pests and disease cycles, suppresses weeds and improves soil health.
Most high productive and profit monocultures farms rely on synthetic chemical fertilizers, pesticides, and herbicides to replenish soil. Though it is effective, it destroys other beneficial factors of soil resulting in overall degradation of the land. Over-reliance on agrochemicals risks a high probability of developing resistant pests and weeds, a devastating outcome.
Crop rotation uses the crops themselves to sustain soil health by promoting a natural system. of repairing soil health instead of reliance of synthetic fertilizers, pesticides, and herbicides.
What are the Benefits of Using Crop Rotation?
A successful crop rotation can increase land yield production and yet minimize the uses of agrochemicals. Therefore, leading to a more sustainable and beneficial farming system.
However, there are disadvantages to crop rotation. Farmers can never specialize in a single crop. Also meaning farmers require more knowledge and skills to work with different crops, and understand the medicinal effect of the preceding crop, to avoid drawbacks such as, creating a green bridge for pests and diseases.
- Increase soil nitrogen by fixing atmospheric nitrogen
- Increased soil organic matter
- Improve soil structure
- Differential extraction of nutrients and moisture from different soil depths
- Encourage soil microbial activity
- Erosion control
- Improved biodiversity
- Limits population of pests and diseases
- Reduces weed stress
- Avoid accumulation of toxins
- Avoid the buildup of resistance of insects, pathogens, and weeds
- Specialization in one crop is not possible
- Requirement of equipment and machinery varies from crop to crop
- Allopathic effect of preceding crop
- Serves as alternate hosts for pests and diseases
- Requires more knowledge and skills
- The difference in growing conditions
Principles of Crop Rotation
Before adopting the principles of rotation, farmers need to understand a few factors. Different crop requires different growing conditions. Farmers need to know the climatic conditions. the area, soil type, and fertility.
Some basic principles of crop rotations include:
- Crops with deep roots should be followed by those with shallow roots. This helps proper and uniform use of nutrients from the different depths of soil.
- Crops with fibrous root systems should be grown after tap-rooted crops. This will add more organic matter to the soil.
- The non-leguminous crops should be followed by leguminous crops. Legumes fix atmospheric nitrogen in the soil and add more organic matter to the soil.
- More exhaustive crops should be followed by less exhaustive/ restorative crops.
- Same family crops should not be grown in succession because they act as alternate hosts for pests and diseases.
- Crops susceptible to stagnant pests and diseases should be followed by tolerant crops.
- Crops with problematic weeds should be followed by a cover crop to suppress the weeds and replenish the soil as green manure.
Then come detailed planning for the crop chosen, study them well to fit into the crop rotation. E.g. Potatoes dislike lime as it increases the chances of getting scabs whereas brassicas like limey soil. Therefore, providing a big time gap between them is desired in the rotation. Also, take note that root crop such as carrots do not want soil that has been manured as it cause them to fork and split.
Application of Crop Rotation
There are many ways in approaching crop rotation and there no limit to the number of crops used in a rotation. However, the more different types of plants, or more specifically plant families grown, the better the rotational value will be achieved.
A tropical climate can grow many crops in a single year. Thus, there is a variety of crops combination available for rotation. Some farmers may even incorporate grass in the rotation. Where pasture will be part of the rotation to include livestock.
Designing crop rotation can be complicated, but to make it easier farmers may rotate crops according to:
- Plant family
- Plant part harvested
- Plant compatibility
- Plant nutrient requirements
- Rooting depth & type
- Including legumes & cover crops
A simple 4 growing cycle of tropical crop rotation following plant part harvested will look like this:
|First growing||Second growing||Third growing||Forth growing|
Even though this crop rotation is made only based on plant parts harvested but it has included some of the basic principles. They are usually from different families, with different rooting depts, and legume is also a restorative crop.
Remember to manage the time for each growing timeframe; utilize each plot timely to avoid back clash. Farmers should be able to produce the same amount of products at any given time when it’s timed well.
One has to have the skills to know what crops can be planted after the other for the process to be successful. A poorly designed or executed crop rotation may take years to appear, and many more years to be corrected. Farmers should be vigilant as well as ready to practice crop rotation as required. Always keep farm records!