FIELD PLOT TECH NIC 65 



SUMMARY OF FIELD PLOT TECHNIC 



Following is a brief summary of the more important factors 

 which assist in obtaining reliable plot results. 



1. Soil heterogeneity exists in varying degrees, hence uniform 

 plots should be selected for the field experiments. To aid in 

 determining the comparative uniformity of different fields, 

 Harris' method or the check plot method may be used. 



2. If the field varies uniformly from one side to the other, 

 check plots may be used to correct yields. In general, the use of 

 checks to correct yields is undesirable. 



3. The yield of check plots may be used to determine the prob- 

 able error of the method of work. They should be placed system- 

 atically throughout the experimental plots and the number should 

 be sufficiently large to approach a normal frequency distribution. 



4. Probable errors may be used to determine whether the ob- 

 tained differences between strains are significant and thus aid in 

 eliminating the significantly lower yielders. 



5. The probable error of an experiment may be determined 

 by the pairing method suggested by Wood and Stratton. It is 

 comparable to the one based on the checks and may be used in 

 the same way. 



6. The probable error of an experiment may be reduced most 

 effectively by plot replication. Replication up to a certain 

 number rapidly reduces the probable error, beyond that number 

 additional replications do not proportionately decrease it. The 

 number of replications will depend considerably on the character 

 of the soil and somewhat on the size of the plots. On fairly uni- 

 form land three replications have been found satisfactory for 

 general breeding studies. 



7. Oblong plots sown with an ordinary grain drill give reliable 

 results when their area is approximately J4o acre each. 



8. Plants growing on the border of a plot adjacent to an alley 

 or roadway are usually superior to those growing within the plot, 

 hence, if it is desired to secure yields comparable with those which 

 would be secured under field conditions, the border plants must 

 be discarded. The border should be removed to a depth of at 

 least a foot. Different varieties and strains may have unequal 

 ability to utilize the free space along the pathways between plots 

 and consequently a second reason arises for discarding the border. 



9. Competition exists between nearby varieties and strains, 



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