The practice of growing different crops one after another on the same plot of land in a planned sequence, to maintain soil health, is called:

Crop rotation is the practice of growing different types of crops on the same field in a planned sequence over successive seasons or years, instead of growing the same crop again and again.

Why crop rotation is practised:

Maintains soil fertility: different crops take different amounts and kinds of nutrients from the soil, and from different depths. Rotating them prevents the soil from being depleted of particular nutrients.

Adds nitrogen: including legumes (such as gram, peas, moong or berseem) in the rotation adds nitrogen to the soil through biological nitrogen fixation, which benefits the next crop.

Controls pests and diseases: many pests and pathogens are specific to certain crops. Changing the crop breaks their life cycles.

Controls weeds: different crops and cultivation practices disrupt the growth of particular weeds.

Improves soil structure: crops with different root systems (deep and shallow, fibrous and taproots) improve soil aeration and organic matter.

Reduces soil erosion and the need for chemical fertilisers and pesticides.

Spreads economic risk across different crops.

Examples of crop rotations in India:

• Rice-wheat (the dominant system in the Indo-Gangetic plains).
• Maize-wheat, cotton-wheat and sorghum-chickpea.
• Rice-wheat-moong (with a summer pulse added).
• Groundnut-wheat and soybean-wheat.
• Rice-rice-pulse in the southern deltas.

Problems with continuous rice-wheat cropping:

Declining soil organic matter and fertility, falling groundwater, and pest build-up. Experts recommend diversifying the rotation with pulses, oilseeds and maize.

Historical note:

Crop rotation was practised in ancient times. In medieval Europe, the "three-field system" rotated winter grain, spring crops and fallow.

In the 18th century, the "Norfolk four-course rotation" (wheat, turnips, barley and clover) in England improved yields significantly during the British Agricultural Revolution.

Rotation versus other systems:

• Mixed cropping and intercropping grow crops at the same time on the same field.
• Monoculture grows the same crop continuously.

Why not the other options?

• ✗Monoculture is growing the same single crop repeatedly.
• ✗Mixed cropping is growing two or more crops together at the same time.
• ✗Shifting cultivation involves clearing new forest land when soil fertility declines.