CHAPTER XX 



PENNSYLVANIA FIELD EXPERIMENTS 



IN 1882 the Pennsylvania Agricultural Experiment Station 

 began, at State College, the oldest extensive field experiments now 

 in progress in America. They include four separate fields, each 

 of which contains 36 eighth-acre plots, or 144 different plots in all. 

 A 4-year rotation is practiced, consisting of corn, oats, wheat, 

 and hay (mixed clover and timothy seeded on the wheat land in 

 the early spring) , every crop being represented every year (ex- 

 cepting the hay crop in 1882). The land is quite undulating, but 

 the individual plots are separated by a permanent strip of grass 

 sod or turf about two or three feet wide, which practically pre- 

 vents surface washing from one plot to another, and in but few 

 cases is there evidence of soil washing on the fields. The plots 

 are about i^ rods wide by 16 rods long. 



The soil consists largely of a silty clay loam, and contains perhaps 

 10 per cent of small angular rock fragments, chiefly of chert. 

 While this field had been treated with lime some years before the 

 beginning of these experiments, recent examination has shown that 

 the soil is more or less acid. Even where sodium nitrate has been 

 applied, acidity is found as a rule, notwithstanding the tendency 

 of sodium nitrate to neutralize soil acidity, much of the sodium 

 being left in the soil when the nitrogen is taken up by plants. 

 Where ammonium sulfate has been used, especially where heavy 

 applications are made, the soil is very much more acid; and on 

 such plots the red sorrel (Rumex acetocelld) is becoming a pest, and 

 a good stand of clover is not secured as a rule. As hereinbefore 

 stated, the average soil of this field contains 2320 pounds of nitro- 

 gen, 1080 pounds of acid-soluble phosphorus, and 50,700 pounds 

 of total potassium, in 2 million pounds of the surface soil. 



420 



