Crop Rotation: All You Need to Know

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Decades before we had chemical fertilizers to maintain the farm’s nutrients, and chemical pesticides and herbicides to keep away the pests and weeds, we had crop rotation. Crop rotation is a method for balancing a portion of land through various crops, reducing chemical fertilizers, pesticides and herbicides. It has been in practice over centuries, and successful farmers nurtured their land over generations. Even today, it remains critical for farmers wanting to nourish their local environment while growing good, healthy food crops.

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Here, we present all the information about crop rotation and how and why it is relevant.

What is Crop Rotation?

Crop rotation is nothing but the cultivation of different crops on a particular piece of land over some time. The succession of crops that needs to be grown is carefully chosen so that it solves the following three purposes

  • The nutrients in the soil are maintained, 
  • Controlling the population of the pest. 
  • Suppression of weeds.  

A crop rotation will cycle through cash crops (crop diversification) like vegetables, cover crops such as grasses and cereals) and green manures (often legumes). The exact sequence of crops depends on local circumstances. One needs to have a critical understanding of each crop’s contribution and what it takes from the soil. For instance, nitrogen depleting crop should precede a nitrogen-fixing harvest.

The main idea is to have the crops sustain soil health on their own. Instead of harvesting the same crop year after year and repairing soil health through fertilizers, pesticides, and herbicides, crop rotation allows different harvesting crops every season.

What are the Advantages of Crop Rotation?

A well-designed crop rotation makes farmland both more productive and more environmentally stable. Subsequently, it increases productivity, thereby improving the financial viability of a farm. Simultaneously, it reduces chemical input costs. The primary advantages of crop rotation are:

  • Pest control
  • Improved soil fertility and structure
  • Disease control
  • Increased Soil Organic Matter
  • Weed control
  • Increased yield
  • Erosion control
  • Improved biodiversity
  • Reduced commercial risk

Crop Rotation Gives Improved Soil Structure and Fertility

Crop rotation improves the chemical and physical conditions of soil and thus improves the overall fertility. Nitrogen-fixing legumes such as alfalfa and soybeans in crop rotations fix atmospheric nitrogen into the soil through root nodules. This nitrogen is made available for subsequent crops.

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Deep-rooted cover crops can draw up nutrients such as potassium and phosphorus from deep soil, making these nutrients available for subsequent shallow-rooted cash crops.

Soil tilth is the physical condition of the soil as it relates to plant growth. A favorable tilth means good conditions for seed germination and root proliferation, thereby allowing crops to thrive. Additionally, the soil with good tilth facilitates water infiltration and aeration, beneficial for both environment and crop.

There are several approaches to improving the physical quality of the soil, and often a combined approach leads to the most significant improvement. Depending on the crops that are being alternated, You can improve the soil tilth by crop rotation. The usage of cover crops and reducing tillage are some of the other ways of improving soil tilth.

If you grow a hay crop in a rotation, it can improve soil tilth and bulk density. The soil will be loose. Moreover, the soil will have an excellent granular structure and tilth. These improved properties result from the soil getting protection from raindrops, the network of fine roots in the soil, and humus formation from decomposing plant roots.

Crop Rotation for Disease Control

Crop rotation controls common root and stem diseases affecting the row crops. It has proven to be very effective against diseases whose pathogens have a small host range. Additionally, it works very well against the pathogen that requires soil or crop residue to overwinter. Overwintering is how some organisms pass through or wait out the winter season or pass through that period of the year when winter conditions make survival difficult.

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These conditions can be cold or sub-zero temperatures, ice, snow, limited food supplies make a routine activity near impossible.  If you rotate a non-host crop immediately after a host crop, it prevents the reproduction of the pathogen. The pathogen preserved in crop debris does not have the necessary conditions for its survival, and thus, the disease spread is controlled. For example, Farmers can cut the soybean cyst nematode populations by half when they rotate soybean with corn and wheat.

If you grow the same crop on a particular parcel of land after year, you give pathogens continued optimal conditions. Hence, their population grows rapidly.

Crop Rotation for Pest and Weed Control

You can use crop rotation to manage those insects that are non-mobile, whose larvae or eggs overwinter in the soil and have a narrow range of crops to feed.

For instance, rotation technique can effectively manage corn rootworms. These insects lay eggs in the cornfields where they live. Subsequently, they emerge to damage the crops. If you rotate a non-host crop immediately after a corn crop, then the emerging larvae will starve due to food scarcity. However, this practice is ineffective in some areas where rootworm populations have developed mechanisms to survive the rotation technique.

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The cover crops inclusion in the rotation systems provide greater competition to the weeds for their basic needs of nutrients, space and light. The cover crops ultimately crowd out the weeds, slowing down weed growth and proliferation for a reduced weed population in subsequent crops.

Crop Rotation increases Soil Organic Matter

Rotation of crops will add more green manures, crop residues and other plant debris to the soil. It requires less intensive tillage, which means that soil organic matter does not degrade as quickly. The increase in the soil organic matter improves water holding capacity and soil infiltration. Consequently, this enables absorption of water in the soil. Additionally, the increase of soil organic matter improves overall soil structure and the biological and chemical properties of the soil.

Crop Rotation Improves Biodiversity and Increases Yield

The biodiversity of the soil gets improved as the rotation technique changes crop residue and rooting patterns. Different crops benefit different species; thus, a range of crops will lead to a more healthy and diverse soil microbial community. Additionally, the microbial community is supported by rotating crops with a high carbon to nitrogen ratio (as in corn) with low carbon to nitrogen ratio crops (as in soybeans).

Crop rotation can help increase yield. Corn and soybean rotated with another crop yields 10% more than when the same crop is grown continuously. The improved yield results from all of the individual soil and plant health benefits from crop rotation.

Crop Rotation controls Soil Erosion and Reduces Commercial Risks

Crop rotation helps in controlling soil erosion from water and wind by improving the soil structure. It reduces the amount of soil exposed to wind and water. It supports reduced or no-till farming, which ensures even better protection against erosion. Cover crops effectively reduce raindrop impact, reduce sediment detachment and transport, slow surface runoff, and reduce soil loss.

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Crop rotation can be designed to reflect climatic conditions for maximizing the results of erosion control efforts. For example, rigid rotations tend to give good crop growth and adequate soil cover under consistent climatic conditions of fairly predictable annual rainfall and temperature. You require more flexible rotations in regions susceptible to unseasonal rains or drought.

Different crops have different resistance power against different hostile climatic conditions. For example, some crops have good tolerance against flooding conditions. On the other hand, others have improved drought resistance. When you grow different crops in rotation, it minimizes the impact of crop failure due to bad weather.

Crop rotation requires growing and harvesting crops at different times, helping farmers spread their workload evenly and cultivating more land with the same amount of equipment and labour.

How to Introduce a Successful Crop Rotation

Although different farms have their own management and climatic constraints to deal with, you need to follow some general rules for rotation. 

  • You need to strike a balance between non-cash and cash crops. This creates a sustainable and profitable crop rotation system.
  • You must grow deep-rooted plants alternately with the shallow-rooted crops. This type of rotation combination improves drainage capacity and soil structure. For example, the alternate combination of cabbage with corn is a good rotation combination for the physical properties of the soil.
  • You should grow Nitrogen-demanding crops immediately after nitrogen-fixing plants. For example, Corn should succeed soybeans.
  • It would be very effective if you grow plants with high biomass of roots alternately with plants with low biomass of roots. For example, Legumes such as red clover and orchard grass having high root biomass can be grown alternately with low biomass root crops such as soybeans and corn.
  • Very fast-growing crops like buckwheat, sun hemp and radishes should be grown alternately with slow-growing crops like winter wheat and red clover.
  • Slow-growing crops are more vulnerable to weeds. Therefore in a rotation system, they should be grown immediately after weed-suppressing crops such as winter rye.
  • Crop rotation can alternate between autumn and spring crop plantings; This reduces weather risk, spreads work pressure, and suppresses weeds.
  • You must try to cover the soil with crops as much as possible.
  • Alternate leafy crops with straw crops to aid in weed suppression.

Takeaway 

Crop rotation requires thorough and precise planning. An improper and unwise rotation may build up critical pathogens and destroy the balance of nutrients in the soil. A poorly executed or designed crop rotation may take years to appear and many more years to correct.

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