66 EOOT-KNOT AND ITS CONTROL. 



proved so very poor for the oats that for it was substituted Abruzzes 

 rye in succeeding years. Once each year the land was fertiHzed with 

 the special commercial fertilizer previously mentioned at the rate of 

 500 pounds per acre. 



The grain was harvested when mature, thrashed, and measured. 

 As soon as the land could be put into proper condition the beggarweed 

 and velvet bean seed were sown. In October a measured part of each 

 field was carefully mowed and the vines cured to hay and weighed, thus 

 permitting an approximate estimate of the actual yield per acre. The 

 grain was so^vn as soon as the hay crop was cut and the land prepared. 

 Unfortunately it was impossible, in addition to the substitution of rye 

 for oats, to carry out the rotation just as planned, for in 1907 the beg- 

 garweed seed obtained germinated so poorly that those plats were 

 resown to velvet beans, as it was then impossible to get good beggar- 

 weed seed. 



In the summer of 1908 across the south edge of the field rows of 

 tomatoes, beans, okra, and New Era cowpeas were planted to test the 

 degree to which the nematode infestation had been reduced by two 

 years of these rotations. In the spring of 1909 another strip was 

 sown to the same four kinds of plants, the remainder being planted with 

 two varieties of cotton, viz. Triumph and Columbia. A similar area 

 to the north of the rotation fields was also sown to the same sorts of 

 cotton, while to the east was a field of Peterkin cotton belonging to a 

 renter and not planted wdth reference to the experiment. The choice 

 of the field to the north was made through an unfortunate misunder- 

 standing. It was not discovered until the planting was done and the 

 plants above the ground that that field too had undergone somewhat 

 of a rotation, viz, 1906, cotton; summer of 1907, Iron cowpea; A\dnter 

 of 1907-8, rye; summer of 1908, Iron cowpea; winter of 1908-9, rye. 

 The field to the east, which was sown to Peterkin cotton, was in cotton 

 for the third successive season. 



The experiments were further interfered wdth by torrential rains 

 which were harmful in two particulars, viz, they washed out much of 

 the cotton and brought soil from nematode-infested fields and depos- 

 ited it on parts of the rotation plats. 



217 



