CROP ROTATION SYSTEM


A time sequence of CROP SYSTEMS, either sole or overlapped in
phase, on the same PLOT. While a crop rotation system often
implies a regular cyclical pattern over time (often involving a
cycle of -.?re than a year), this need not be so with MULTIPLE
CROPPING. =ee also ROTATION.



CROPPING :--ENSITY INDEX (CII)

A time-wei :ted land-use index that evaluates the fraction of. the
total hectr~;e-months available to the farmer that are used for
crop production. It is calculated as:

 n m
 CIi= sun A t /(AT + sum A t
 i=l i i j=l j j

where: n is the total number of crops sown during the
 period T (usually 12 months)

 A is the area occupied by the ith crop (including
 i where applicable, the jth crop)

 t is the duration of the ith crop or the number of
 i months during which crop i occupied area A
 i

 A is the farmer's total cultivated area available
 during the period T

 m is the total number of crops grown on the
 additional land area A if relevant, available
 J
 for use during the period t
 J

 A is the land area, additional to A, available for
 j short-term use with crop j.

This indeA -an also be used to measure individual crop intensities
relative to the land available to the farmer. To do this the
numer.ator is specified only in terms of one type of crop. The sum
of such individual crop intensities equals the overall cropping
intensity index.


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