Important Indices
Some of the important indices to evaluate the cropping systems are as below:
I) Land Use Efficiency or Assessesment of Land Use:
The main objective is to use available resources effectively.Multiple cropping which include both inter and sequential cropping has the main objective of intensification of cropping with the available resources in a given environment.Several indices have been proposed to compare the efficiencies of different multiple cropping system in turns of land use, and these have been reviewed by Menegay et al. 1978.
1. Multiple Cropping Index or Multiple Cropping Intensity (MCI):
It was proposed by Dalarymple (1971). It is the ratio of total area cropped in a year to the land area available for cultivation and expressed in percentage.
MCI = a1
—– * 100
A
Where i = 1, 2, 3, n, n= total number of crops, ai = area occupied by crop and A= total land area available for cultivation. Or MCI is the sum of area planted to different crops and harvested in a single year divided by total cultivable area and expressed as percentage. Or MCI means the sum of areas under various crops raised in a single years divided by net area available for that cropping pattern multiplied by 100. It is similar to cropping intensity.
MCI = Total number of crops + with their respective area
________________________________________ * 100
Net cultivable area
2. Cultivated Land /Utilization Index ( CLUI):
Cultivated land utilization Index ( Chuang, 1973 ) is calculated by summing the products of land area to each crop, multiplied by the actual duration of that crop divided by the total cultivated land times 365 days.
CLUI = a1d1
________*100
A*365
Where, I = 1, 2, 3, n, n = total number of crops. A1 = area occupied by the ith crop, di = days that the ith crop occupied ai and A = total cultivated land area available for 365 days.
CLUI can be expressed as a fraction or percentage. This gives an idea about how the land area has been put into use. If the index is 1 (100%), it shows that the land has been left fallow and more than 1, tells the specification of intercropping and relay cropping. limitation of CLUI is its inability to consider the land temporarily available to the farmer for cultivation.
3. Crop Intensity Index (CII):
Crop intensity index assesses farmers actual land use in area and time relationship for each crop or group of crops compared to the total available land area and time, including land that is temporarily available for cultivation. It is calculated by summing the product of area and duration of each crop divided by the product of farmers total available cultivated land area and time periods plus the sum of the temporarily available land area with the time of these land areas actually put into use (Menegay et al. 1978). The basic concept of CLUI and CII are similar. However, the latter offers more flexibility when combined with appropriate sampling procedure for determining and evaluating vegetable production and cropping pattern data.
CII = ai.ti
__________
AOT +A1T1
Where, I = 1, 2, 3……NC, NC = total number of crops grown by a farmer during the time period. T, ai = area occupied by ith crop (months that the crop I occupied an area ai) T = time period under study (usually one year), AO= Total cultivated land area available with the farmer for use during the entire time period, T, M= total number of fields temporarily available to the farmer for cropping during time period. T, j=1, 2, 3…….. M, Aj=land area of jth field and Tj= time period Aj is available. When, CII = 1 means that area or land resources have been fully utilized and less than 1 indicates under of resources.
CII indicates the number of times a field is grown with crops in a year. It is calculated by dividing gross cropped area with net area available in the farm, region or country multiplied by 100.
CII = Gross cropped area
________________*100
Net area
When long duration crop grown crop remain longer time in field this is the drawback of CII. So time is not considered, thus , when long duration crops like sugarcane and cotton are in grown, the cropping intensity will be low, though crop remain longer period of time in the field.
4. Specific Crop Intensity Iindex:
Also proposed by Menegay ET. Al. 1978 SCII is a derivative of CII and determines the amount of area – time denoted to each crop or group of crops compared to total available to the farmers.
SCII = ak.tk
_________
AOT+ a1 t1
Where Nk= total number of crops within a sp0ecific designation such as vegetable crops or field crops grown by the farmer during the time period T. AK = area occupied by the kth crop.
Ik= duration of kith crop.
Using this formula vegetable intensity index, rice intensity index, field crops intensity index etc.
5. Diversity Index (DI):
It was suggested by Strought (1975) and Wang and Yu (1975). It measures the multiplicity of crops or farm products which are planted in a single year by computing reciprocal sum of squares of the share of gross revenue received from each individual farm enterprises in a single year.
DI = 1
___________
Yi
_____
Yi
Where,
N = total number of enterprises (crops or farm products) and yi = gross revenue of ith enterprises produced within a year.
6. Harvest Diversity Index (HDI):
It is computed using the same equation as the DI expects that the value of each farm enterprises is replaced by the value of each harvest.
HDI = 1
______
Yi
______
Yi
Where,
Yi = gross value of ith crop planted and harvested within a year.
7. Simultaneous Cropping Index (SCI):
It is computed by multiplying the HDi with 10,000 and dividing the product by MCI. (Strout, 1975).
SCI = HDIx10, 000
____________
MCI
8. Relative Cropping Intensity Index (RCII):
It is the modification of CII and determines the amount of area and time allotted to 1 crop or groups of crop related to area- time actually used in the production of all crops. RCII numerator equal SCII denominator and RCII denominator equal CII numerator.
RCII = ak.tk
_______
ai.ti
These indices can be used for classifying (i.e a farmer with relative vegetable intensity index 50% would be considered a vegetable grower.) measuring shifts of various crops among farm of different sizes and determining whether the consistent types of cropping pattern occur within various farm size strata. These indices also held to know how intensity cultivated land, area has been utilized. But none of these indices takes productivity into account and cannot be used for comparing different cropping systems and evaluating their efficiency in utilization of the resources other than the land.
9. Crop Equivalent Yield (CEY):
Many types of crops/ cultivars are included in a multiple cropping sequences. It is very difficult to compare the economic produce of one crop to another. To cite an example, yield of rice cannot be compared with the yield of grain cereals or pulse crops and so on. In such situations, comparisons can be made based on economic returns (gross or net returns). The yield of protein and carbohydrate equivalent can also be calculated for valid comparison, Effort have also been made to convert the yields of different crops into equivalent yield of any one crop such as wheat equivalent yield ( Lal and Ray, 1976 and Verma and Modgel,1983 ). Verma and Modgel, (1983) evolved the equation for calculating wheat equivalent yield (WEY).
Crop equivalent yields (CEY): The yields of different intercrops are converted into equivalent yield of any one crop based on price of the produce.