The net irrigation requirement of a crop is the amount of water that needs to be supplied through irrigation to meet the water requirements of the crop. It is crucial to accurately determine the net irrigation requirement in order to optimize water usage and ensure the health and productivity of the crop.

The net irrigation requirement can be calculated by considering various factors such as the consumptive use, effective rainfall, leaching, and other requirements. Let's understand each of these factors in detail:

1. Consumptive use: Consumptive use refers to the amount of water that is consumed by the crop through transpiration and evaporation. It is the water that is taken up by the plants and lost to the atmosphere. The consumptive use of a crop depends on various factors such as crop type, growth stage, weather conditions, and soil properties. It is an essential component in calculating the net irrigation requirement as it represents the base water requirement of the crop.

2. Effective rainfall: Effective rainfall is the amount of rainfall that contributes to the soil moisture available for the crop. It is the portion of the total rainfall that is not lost through runoff or evaporation. Effective rainfall is crucial in determining the net irrigation requirement as it reduces the amount of irrigation water needed. It replenishes the soil moisture and reduces the deficit between the consumptive use and the available water.

3. Leaching and other requirements: Leaching refers to the process of flushing out excess salts and nutrients from the root zone of the soil. It is essential to prevent the buildup of salts that can be harmful to the crop. Other requirements may include specific water needs for certain crops, such as paddy fields requiring flooded conditions. These additional requirements must be taken into account when calculating the net irrigation requirement.

4. Percolation loss: Percolation loss refers to the amount of water that seeps below the root zone and is lost beyond the reach of the crop's roots. It is considered a loss as it does not contribute to meeting the crop's water requirements. In the context of the given options, percolation loss is not considered in the calculation of net irrigation requirement.

Therefore, the correct answer is option 'C' - consumptive use, effective rainfall, leaching, and other requirements. These factors collectively determine the net irrigation requirement of a crop by considering the base water requirement (consumptive use), the contribution of rainfall (effective rainfall), and other specific needs like leaching and additional requirements.