Keiztuoky Agricu1z‘ural El'[)6I"Z'77l€7lt Station 15
Effect of Return of Crop Residues on Yield of Crops. On
the Lexington soil experiment field, in a rotation of eorn, soy-
beans, wheat and elover, no increase of erops was obtained by
the return of eornstalks, soybean and wheat straw to certain
I fertilized and unfertilized plots, the diiferenees between residue
i and no residue plots being easily within the limits of experi-
L mental error. ln the latter half of the period the residues
I seemed to depress the yield of eorn.
3 During the last six years of the foregoing experiment,
} manure has been used in various ways in a rotation of eorn,
l wheat and elover. Six tons of manure per aere increased the
D yield of eorn an average of 5.6 bushels per aere; of wheat fol-
S lowing corn, 1.8 bushels. The inerease of elover following the
wheat was small, being only 128 pounds per aere. On un-
it manured ground, the yields were; eorn, 52.5 bushels; wheat, 24
(3 bushels, and elover, 3,465 pounds. The yields of the untreated
H plots in the four-year rotation were praetieally the same as
.() these. e
0 Japan Clover in Legume Mixtures. In the spring of 1925,
{_ Japan elover was introdueed into the elover and grass mixtures
d ‘ used on the experiment fields, using 5 pounds in a 15-pound
lc V mixture per aere. ln ease of failure of other elovers, it was
lc thought that the Japan elover might reseed itself and produee
S_ a crop of hay at least on the better plots and also provide a
tg legume for the eheek plots and unlimed plots where red and
is alsike elover make little or no growth. Altho the period of the
Q_ trials has been short, some very promising results have been
,€_ obtained. On aeeount of drouth. the general mixture was a
,O_ failure on most of the fields, with some Japan clover persist-
ing but not making enough seed for a satisfaetory stand the
{lv V next year. On. the (`ampbellsville lield, wllere the general mix-
hlb ture was a failure. enoughJapan elover persisted to form a
ml good seed erop in the fall of 1925. A good stand appeared in
rc 1926, giving the following hay jrields Wlllltfll are avei·ages ol' all
` eomparable treatments; no ll`·'*2ltlll+"llT. l,T7fl pounds; aeid phos-
  phate. 2.2304 pounds; limestone and arid pliosphate ILUG!)
` pounds; rock phosphate, 3,724 pounds. The effeet of rock