Table of Contents:
- What is crop combination?
- Why do we need to study crop combinations?
- Weaver method of crop combination
- DOI method of crop combination
What are crop combinations?
- Some crops are generally not grown in absolute isolation or they will grow better if associated crops are grown with them.
- Various environment or mutual interaction supports each other.
- Crops associated with a particular field or area in one agricultural year are called Crop combinations.
For example,
In Kharif season,
- One combination of the crop could be; Maize crop + Beans+ Cucumber;
- Maize crops provide support to beans and cucumber.
- Bean roots fix the nitrogen and provide nitrogen to maize.
Why do we study crop combination:
Crop combination has great importance in the agricultural economy for the following reasons:
- Crop combination is done within the season for good yield
- Crop combination is used for one agriculture year for intensive farming
- Crop combination is done for nutrients enrichment and environment conservation
- Used to classify the agricultural region based on the crop combination ranking as agricultural region delineated by mono-crop ranking is not really correct.
- Used in land utilization and land planning
- Used to make agriculture policy
There are different methods to find out the best possible crop combination ;
- J C Weaver Method( 1954)
- Doi Methods( 1959)
- Ayyar-1909
- Rafiullah(1956)
J C Weaver method of crop combination:
- Weaver was the first geographer who used statistical techniques to show crop combinations based on the study of the middle west USA.
Basic Assumptions:
- The study of crop combination or delineation of crop combination region is done based on the main crop, not secondary crops.
- The ideal distribution of crop areas is divided into equal areas between the number of crops
Steps to calculating the crop combination:
First,
- arrange the actual crops areas in decrement order
Second,
- Finding the deviation;
- d=ideal distribution-actual distribution of cropping areas
Third,
- Finding the Crop combination Index for each sample;
- S= ∑d^2/n
Fourth,
A sample of having a Minimum crop Combination Index will be the best crop combination for that region or field.
Let us the analysis with data with the help of the following table
Ideal share of the crop:
Crop Combination
|
Theoretical /Ideal %
|
One Crop
|
100 %
|
2 crops
|
50% each
|
3 crops
|
33.33 % each
|
4 crops
|
25 % each
|
As per Weaver crop combination:
|
|
One crop
|
2 crops
|
3 crops
|
4 crops
|
Theoretical share in %
|
100
|
50
|
33.33
|
25
|
Actual share in %
|
80
|
50,40
|
40,30,20
|
40,25,15,10
|
Finding deviation d( Theoretical % - actual %)
|
20
|
0,10
|
-6.7,3.3,13.3
|
-15,0,10,15
|
Summation of Di^2
|
400
|
100
|
232.67
|
550
|
Crop combination index S= ∑d^2/n
|
400
|
50
|
77.55
|
137.5
|
Weaver criticism:
- Weaver study based on the USA field.
- In the USA, field size is larger and also not many crops are grown due to climate limitation.
- Weaver method is not suitable for India
- As Weaver ignored crops that are grown in less than 10 % of areas.
- Weaver did not include cattle rearing in this method.
Doi method of crop combination:
Doi modified the Weaver formula for finding crop combination index.
Doi formula:
Crop combination index S= ∑d^2
Doi formula is more accurate in intensive farming countries like India.
For a detailed explanation, watch the below video:
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