Farmers in Northern India grow legumes as fodder in one season wheat in the next season.
What is this practice known as ?

Explanation

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks about the agricultural practice where farmers in Northern India grow legumes in one season and wheat in the next season.

2. **Identifying the Crops**: The crops mentioned are legumes (which are often used as fodder) and wheat. Legumes are known for their ability to fix nitrogen in the soil.

3. **Recognizing the Importance of Nitrogen**: Wheat is a crop that requires a lot of nitrogen from the soil. Continuous cultivation of wheat can deplete the nitrogen levels in the soil.

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