There are some important terms as applied to crops:

  1. Dry crops. These crops grown without irrigation.
  2. Wet crops. These crops grown with irrigation water.
  3. Crop ratio. It is the ratio of the areas irrigated in Rabi and Kharif seasons.

\[Crop ratio= \frac{Area irrigated during Rabi season}{Area irrigated during Kharif season}\]

  • Water requirements of Kharif crops is much more than those of rabi crops.
  • The crop ratio in two seasons  such that water requirements of crops e from the canal throughout the year.

4. Overlap Allowance.

  • Sometimes, it so happens that crop of previous crop season has not yet been harvest and the crop of coming season has also been sown.
  • Under such circumstances irrigation water will have to be providedfor some time to both the crops.
  • The time period in days for which crop of previous season overlaps the new sown crop is knownas overlap allowance.
  • Since during overlap period, both the crops require water, additional supplies will have to be supplied to the canal to cater the needs of both the crops.

5. Deep Rooted Crops.

  • Such crops whose roots lead to comparatively larger depths, are know  deep rootedcrops. Cotton, Arhar, Hemp etc.
  • are the examples of deep rootedcrop.

6. Shallow Rooted Crops.

  • The crops whose roots remain in the upper layer of the soil are termed as shallow rooted crops.
  • Wheat, Barley are the examples of such crops.

7. Leguminous Crops.

  • These are such crops which increase the fertility of the soil by being in the field.
  • These crops gather Nitrogen in their root zone and this nitrogen is utilised by the subsequent crop in that field in form of fertilizer.

8. Garden Crops.

  • These are fruit crops. They require watering throughout the year.

9. Root Zone Depth.

  • It is that depth of the soil upto which roots of crops may lead.

10. Mixed Crop.

  • When two crops are sown in the same field simultaneously the resulting crop is known as mixed crop.
  • Combination of wheat and gram, cotton and til, cotton and moong, are the examples of mixed crops.

11. Double Crop.

  • When two crops of short duration are grownin the same field in the same season one after the other, they are knownas double crop.

12. Rotation of Crops.

  • Different crops have different depths of their root-zones, and as such draw out nutrients from different depths of soil, during the process of their growth.
  • If the same crop is sown in the same field repeatedly, the yield of the crop is almost certain to fall.
  • This happens because soil does not get time to replenish the already depleted fertility of the soil of previous season.
  • By practicing rotation of the crops in the same field, the fertility of the field can be maintainedat its usual level without leaving fields empty.

1. In rotation of the crops deep rooted and shallow rooted crops should be  alternately.

  • By doing so the crop nutrients from the soil would be use uniformly from different depths of the soil.

2. If leguminous crop is introduced in rotation, the fertility of the soil can be increased instead of maintaining at constant level.

  • Such crops increase nitrogen content in the soil.
  • Following are the advantages of rotation of the crops:
  1. 1. Nutrients from different depths of soil are use more balancedly.
  2. Fertility of the field can be improvedby introducing leguminous crops in rotation.
  3. The fields are not require to be  vacant after each crop.
  4. Crop disease in the fields can be checke.

Following may be the useful rotations of crops:

  1. Cotton—Spiked millet—Gram.
  2. Cotton—Wheat or Gram.
  3. Wheat—Great millet—Gram.
  4. Rice—Grain.