Crop evaluation before harvest/

Crop evaluation before harvest

Evaluating maize (corn) before harvest is crucial for determining the optimal time to start the harvest and ensuring the maximum yield and quality of the crop. The evaluation focuses on several key indicators that signal the crop's readiness for harvest. These indicators relate to the physiological maturity of the maize, the moisture content of the kernels, and the condition of the stalks and leaves. By carefully monitoring these signs, farmers can decide the best time to harvest their maize to achieve the highest quality and minimize losses.

Key Factors for Maize Crop Evaluation Before Harvest

1. Kernel Moisture Content

The moisture content of the maize kernels is one of the most critical factors in deciding when to harvest. Ideally, kernels should be harvested when their moisture content is between 20% and 25% for high moisture corn that will be stored in silos or used for silage. For grain that will be dried and stored, the desired moisture content at harvest is typically around 15% to 18%. Harvesting at the correct moisture content is essential for preventing mold growth and ensuring the grain is suitable for storage.

2. Kernel Black Layer Formation

The formation of a black layer at the base of the maize kernels is a clear indicator of physiological maturity. This black layer signifies that the kernel has ceased exchanging nutrients with the rest of the plant, indicating that the kernels have reached their maximum dry matter accumulation and are ready for harvest. This stage typically occurs when the moisture content of the kernels is approximately 30%, after which it gradually decreases to the ideal harvest moisture levels.

3. Stalk and Leaf Condition

Evaluating the condition of the stalks and leaves can provide insights into the overall health of the crop and its readiness for harvest. Stalks that begin to lose their green color and become more brittle may indicate that the plant is nearing or has reached maturity. However, it's essential to balance timely harvest with the risk of stalk lodging (falling over), especially in conditions where the stalks become too dry.

4. Grain Fill and Cob Firmness

Assessing the grain fill and firmness of the cob can help determine if the maize has reached its full potential. Well-filled kernels that tightly pack the cob and a firm cob structure are good indicators of crop maturity and readiness for harvest.

When to Start the Harvest

The ideal time to start the maize harvest varies depending on geographic location, weather conditions, and the specific maize variety. However, the general rule is to begin the harvest when the majority of the crop meets the optimal criteria for moisture content, physiological maturity (black layer formation), and overall plant health. Monitoring weather forecasts is also crucial, as adverse weather conditions (e.g., heavy rains, early frost) can necessitate adjusting the harvest timing to protect the crop's quality.


Evaluating a maize crop before harvest requires careful consideration of several factors, including kernel moisture content, the formation of the black layer, and the condition of the stalks and leaves. By closely monitoring these indicators, farmers can optimize their harvest timing to ensure the highest yield and quality of their maize crop. Proper evaluation and timely harvest are essential components of successful maize production, impacting both the immediate returns and the long-term sustainability of farming operations.