Crop Classification based on Purpose in the Field

There are a number of different purposes and uses of the crops. The crops and cropping systems can be classified in a number of different ways based on a long list of categories. Previously we have discussed 'Botanical classification of plants' and 'Agronomic Use classification of the crops'. Now, we will discuss a classification of crops based on their use in the field in different cropping systems;

Crop Classification based on Purpose in field (article cover)

1. Catch crops or Contingent Crops

Catch crops are cultivated in the field to catch the forthcoming season. The main reason for their plantation is that the main crop has failed in the field due to any biotic or abiotic stress. Hence, these crops are cultivated in the field for a number of reason;

� They are fast growth rate and short duration crops.

� They can be easily harvested or used in the field at any desired time (for example, as green manure).

� They are easily adaptable to the season, soil and farm management practices.

Advantages

� Provide feed for animals

� Act to reduce or check the weed growth

� Conserve soil, moisture and fertilizers.

Examples: Chickpea, cowpea, onion, bajra, coriander and onion.

Chickpea field

2. Restorative Crops

Restorative crops are known for their positive impact on the soil since they add organic matter to soil as well as root nodules in the roots of these crops fix atmospheric nitrogen into nitrates and nitrites in the soil and thus enhance the fertility of such soils. The plants also have a habit of shedding their leaves while reaching maturity and add more nutrients to soil. These crops also have produce good and economic yields.

Example: all leguminous crops such as lentils, mung, mash, cowpea.

Lentil Crop

3. Exhaustive Crops

Exhaustive crops are known for consuming the soil contents more aggressively and hence after the harvest the soil is said to have been �exhaustive� and require a lot of fertilizer addition (both organic and chemical fertilizers).

Examples: Sunflower, eggplant (brinjal) and linseed (alsi).

Brinjal Plant

4. Residual or Paira Crops

Residual crops are called so because their purpose is to utilize the moisture in the field left when the previous crop is near harvest. So these crops are sown in the fields without preparatory tillage with the near harvest crop. This practice is also known as �relay cropping� since it is just like relay race, when a running partner hands over the torch to next partner on the track. Similarly, both crops here are also on the same field for some time.

Examples: cultivation of pulses (lentil, chickpea etc.) in the paddy fields to conserve moisture.

5. Cover crops

Cover crops are known for their potential to hold the soil particles together to protect against soil erosion through wind and water. These plants protect the soil either through ground covering foliage or root mats which do not let the soil particles to conserving soil texture and protecting soil structure.

Examples: groundnuts, chickpea and sweet potato.

6. Barrier or Guard crops

Barriers crops are plants/trees which are sown along the edge of the fields, or plots to protect the main crop from the harms of intensity of wind or against trespassing.

Examples: safflower around chickpea, sorghum around cotton and mesta around sugarcane.

7. Alley Crops

Alley crops are called so because these are planted in the �alleys� created between plantations of trees or shrubs. Their main purpose is the restoration of soil fertility and reduction of soil erosion. Their growth is usually not stopped by the shade of these trees and shrubs.  

Examples: growing pulses between trees of Casuarina.

Alley cropping

8. Smother Crops

The word �smother� means �to kill�. These crops are called so because of their ability to check weed growth because of their quick growth, dense foliage and heavy tillering or trailing habit.

Examples: cowpea, mustard and barley.

9. Nurse Crops

These are the crops which are cultivated along main crops in the field and their function is to enhance or maintain the fertility in the soil or fix the atmospheric nitrogen because they have root nodules.

Examples: some legume crop incorporated with cereals.

Legume intercropping in Wheat field

10. Trap Crops

These are crops grown in the fields of main crops for trapping the harmful insects, nematodes or weeds.

Examples: nematodes are trapped by the roots of solanaceous crops and the nematodes can be removed when these trap crops are uprooted from the field. Similarly, castor incorporated in cotton and groundnut act as trap crop for army worm pest.