288 STATE BOARD OF AGRICULTURE. 



as it contains a relatively small anionnt of phosphoric acid. Wlien this 

 (leticiency is corrected by the use of two hundred pounds per acre of 

 acid phosphate the increase lias been sufficient to pay the cost of the 

 fertilizer and nearly double the value of the manure. Michigan farm- 

 ers have generally paid little if any attention to this point. If the 

 practice of reinforcing manure with phosphate should be generally 

 adopted, it would no doubt result in materially increasing crop yields 

 of the State. 



In Table IV are given the average yields and the average annual 

 values of various crops grown in rotation. Many valuable lessons may 

 doubtless be drawn from this part of the experiment, especially after 

 the experiment has been carried on for a few more years and statistics 

 on the cost of producing the various crops have been obtained. The 

 average yields of crops grown continuously on the same plats include 

 those grown the first one or two years of the experiment, which were 

 fairly large. In the last few years the yields on plats devoted to con- 

 tinuous culture of the same crops have come to a very low average, in 

 some cases being far below the cost of production. Difficulty has been 

 experienced in securing a stand of beets on the plat devoted continuously 

 to this crop, many of the beets dying after germination. 



This experiment is now in its its sixth year, which will complete the 

 second round of the rotation. This is a favorable time to consider the 

 results in view of any possible changes that may seem necessary in 

 carrying out this experiment. The difference in natural fertility in 

 some of the plats has been a disturbing factor in the experiment. How- 

 ever, by use of the check plats and the triplication of the plats this 

 factor has been largely overcome. It is believed on account of the 

 residual effect of the manure and fertilizer these treatments will win 

 out even against the natural differences that exist in plats. 



More irregularity has been manifested in the yields of clover than 

 in the other crops and this may be attributed in a large degree to the 

 lack of lime. In 1912 ground limestone was applied at the rate of two 

 tons per acre on the north half of all the plats in two of the series. 

 Little effect of this treatment could be observed in 1912, '13 and '14, 

 but in 1915 a rather marked effect was noticeable in the clover and 

 the same condition may be observed in the 191G crop. The clover on 

 the limed portion of the plat has been of a much larger, thicker and 

 more even growth and more free from weeds, especially sorrel. The 

 difference between the limed and unlimed portions has been more mark- 

 ed on the fertilized plats than on the unfertilized and less marked on 

 the manured than on the unmanured. It is planned to make a fairly 

 liberal application of lime, with the possible exception of one or two 

 plats in each series as a check on this point. Additional tile drainage 

 is also required on some of the plats. 



This experiment was planned mainly for the purpose of determining 

 the best rotations and the best farm practices in regard to use of 

 manures and fertilizers. However, on the average farm some manure 

 or other organic matter is returned to the soil while in many of these 

 plats nothing has been returned and doubtless on account of this some 

 of the crop yields have not been as large as we would desire. It may 

 be best to make such an application of manure to the rotation plats^ oc- 



