CROPPING PATTERN AND WATER RELATIONS 365 



The close relation between the probability distribution and the formula 

 for diminishing returns as yield equation and the claim that the growth 

 factor b -see formula 3- is constant makes it plausible to assume also the 

 constancy of a^ in formula 2. 



By fitting the parabola through the frequency curves of the crops a 

 representation of the cropping system is obtained, depicted by the parabola 

 and the origin of the co-ordinate axes. Herewith the cropping pattern is 

 condensed to a maximum of information with a minimum of constants. 

 This will increase the accuracy of the result or reduce the quantity of needed 

 data. 



The curves show the well-known preference of different crops for 

 hghter or heavier soils or lower or liigher groundwater levels. The graphs 

 may be useful for the prognosis of the change in farming type due to 

 improvements in the ecological, organisational or economic situation. 

 They also may be used for comparing cropping patterns in different areas 

 after correcting for one or more factors that influence the cropping pattern 

 most strongly. 



The parabola method gives a fair basis for the study of the changes in 

 crop frequency as a result of changes in the environment of agricultural 

 production. 



