1.8 Harvesting

Harvesting is the process of gathering the matured crop from the field. It is an important step in crop production as it determines the quality and quantity of the yield. The timing of harvesting depends on the type of crop, the purpose of cultivation, and climatic conditions. Crops should be harvested at the right stage of maturity to avoid loss or damage.

The following are the main points related to harvesting:

• Timing of Harvesting: Harvesting should be done when the crop reaches full maturity, which is when the grains or fruits are fully developed and have reached the desired moisture content. If harvested too early, the yield will be less and not fully developed; if too late, the crop may suffer losses due to pests, diseases, or environmental factors.
• Indicators of Maturity: The maturity of the crop can be determined by the following signs:
  • The color of the leaves changes (e.g., yellowing of paddy leaves).
  • The grains or fruits reach their full size and firmness.
  • The crop starts to shed seeds naturally, such as in cereals like wheat or rice.
  • The moisture content of the crop decreases to an optimal level.
• Methods of Harvesting: Harvesting can be done manually or with the help of machines, depending on the size of the farm and the crop type.
  • Manual Harvesting: This method involves the use of tools like sickles or knives to cut the crops. It is commonly used in small-scale farming, especially for crops like rice, wheat, and vegetables.
  • Mechanical Harvesting: For large-scale farming, machines such as harvesters or combine harvesters are used. These machines can cut, thresh, and gather the crop in a single operation, making harvesting faster and more efficient.
• Post-Harvest Handling: After harvesting, the crops need to be handled with care to prevent damage. This includes activities like threshing, drying, and cleaning to remove unwanted materials like husks, dirt, or pests.
• Threshing: This is the process of separating the grain or seed from the harvested crop. It can be done manually by beating the crop or using machines. The efficiency of threshing determines the overall quality of the harvested product.
• Drying: After threshing, the grains or seeds are dried to reduce their moisture content, which helps in long-term storage and prevents spoilage. This is done by spreading the grains under the sun or using artificial drying methods.

For cereals, the typical moisture content after drying should be around 12-14%. If the moisture content is too high, the grains may spoil due to mold growth. The moisture content is generally measured using a moisture meter.

The moisture content $M$ in the crop is calculated by the formula:

$M = \frac{W_{\text{wet}} - W_{\text{dry}}}{W_{\text{wet}}} \times 100$

Where:

• $W_{\text{wet}}$ is the weight of the crop before drying (in grams).
• $W_{\text{dry}}$ is the weight of the crop after drying (in grams).

After proper drying, the harvested crop can be stored in silos, granaries, or storage bins. The storage conditions must be appropriate to avoid pest infestation, humidity, and other factors that can spoil the produce.

Harvesting is a crucial step that affects the overall yield and quality of crops. Timely and efficient harvesting, along with proper post-harvest management, helps to ensure that the produce reaches the market in good condition.