16 



SCIENTIFIC AGRICULTURE 



September. 1921 



and tliat a long narrow plot is preferable 

 to a square one vr a wide oblong because 

 there is less tendency for variation in the 

 soil sufficient to influence results in a long 

 narrow piece of land than in a square or 

 nearly square one. I liave found that 

 plots which are two rods wide and eight 

 rods long, containing one tenth of an acre 

 are very convenient. This style of plot is 

 used in nearly all the Dry Land Agricul- 

 ture experiments from Texas to North Da- 

 kota inclusive. These plots are usually se- 

 l)arated by alleys or division stri]is 40 i)i- 

 ches in width which are kept cultivated. 

 An alley of this width permits cutting of 

 the grain with a five foot binder and leaves 

 very little danger that the crops on ad- 

 joining plots will become mixed if the crop 

 is lodged. I have tried using acre blocks 

 for certain classes of tillage or planting 

 experiments such as listing versus drilling 

 versus check planting corn and found them 

 satisfactory for this type of work but for 

 ordinary plot experiments the acre size is 

 too cumbersome. In laying out an experi- 

 mental field of this kind, the field is first 

 staked off in strips 132 feet wide with 20 

 foot roads between tliem. These strips are 

 designated as series. Next, these series are 

 divided into blocks 360 feet in length. Iron 

 stakes made out of II/4 inch pipe are set 

 as markers in the middle of each 20 foot 

 road to locate the end of the blocks. These 

 stakes are prefci-ably 18 inches long and 

 set Avitli 17 inches in the ground. It is 

 well worth while to set them in concrete to 

 make the mark i^ermanent and easy to find. 



Replication of Plots. 



All exi)eriiueiita] plot woi-k should 

 be repeated as many times as ])os- 

 siblc each season. l)ui)licates ai'c bet- 

 tci- than singles and triplicates are bet- 

 ter than duplicates, because the results 

 when averaged tend to ecpialize. Mathe- 

 matical attempts to correct errors arl)itra- 

 rily by means of check plots, planted at in- 

 tervals as was formerly the custom on 

 many stations, are likely to lead one into 

 greater errors than if llic actual yields are 

 used, because tlie several mathematical me- 

 thods of correcting yi(Ods to cojiform with 

 check jdcts are all based upon the false 

 liyi)othesis that the land between check 

 ])l()ts varies uniformly. 



It is better to limit the work to tliat 

 which can be well done and sufficiently re- 

 plicated rather than to be too ambitious 

 and attempt to do so great a mass of work 

 on a small piece of land that no definite 

 conclusions can be drawn even after the 

 work is done. 



Only One Thing at a Time 



It is hardly necessary to emphasize tlie 

 desirability of having but one variable and 

 keeping all other conditions of an experi- 

 ment as uniform as possibe. I recall one 

 station superintendent who planned to kill 

 two bii'ds with one stone as he said. He 

 l)lanted different varieties on his rotation 

 ])lots, thus hoping to get a comparison of 

 varieties and rotations at the same time. It 

 would have been a fine scheme if it had 

 worked but for some reason the superin- 

 tendent resigned and his successor revert- 

 ed to the old plan of doing but one thing 

 at a time. 



Experimental Farm Practice 



For the most part, ordinary machinery 

 can be used with satisfaction but there are 

 certain special requirements for some of 

 the experimental machines that may well 

 be enumerated. 



Flowing. — In order to avoid forming 

 dead furrows or back furrows on small 

 fields a two way plow is desirable. These 

 can be had in either mold board or disc 

 type. The disc plow is very useful for 

 plowing in dry weather. I have fre(iuently 

 found it necessary to do all fall plowing 

 with a disc plow. 



Planting. — For loam soils, in good con- 

 dition, I like a double disc drill. For light 

 oi- sandy soils, a single disc drill with press 

 wheel attachments is very suitable. For 

 clay soils, the single disc without press 

 wheel attachments, gives good penetration. 

 Seven feet in width with 14 furrow open- 

 ers is a convenient size. Two horses can 

 pull a drill of that size easily so that there 

 is no trouble driving straight. Row crops 

 such as corn, reiiuire a two liorse corn 

 jilantei- for convenient handling. 



Cidfiratinf/. — For fallow ground the 

 dnckfoot cultivator is almost indispensable 

 and from reports which I have heard of the 

 I'otary rod weedei* I feel sure it will be 

 useful. osp(>('ially on light soils that can- 



