157 



crop of the common red clover. We set a good stand in the spring and when 

 the wheat crop is removed we find a sulhcient number of clover ]»lants. but over 

 (onsiderablc areas their growth is small, and remains so throughout the season. 

 'J'here will be occasional patches of fairly good clover, especially where barn- 

 yard manure or certain nitrogenous chemical fertilizers have been used, but even 

 in these cases the growth is far from perfect. 



Since isr>:{ an experiment has been in progress at this station in which corn, 

 oats, and wheat are grown in rotation, followed by two years in clover and tim- 

 othy, the test being duplicated on five tracts of land, so that each crop is repre- 

 sented every season. Each tract is divided into thirty plats. Every third plat 

 is left continuously unfertilized, while fertilizers of different composition, yre 

 applied to the cereal crops on the plats l)etween. In 1000 we began dressing 

 tliese tracts with lime, .-ipjilying caustic lime as a cross dressing to one-half of 

 each plat. The lime has been apjilied as a surface dressing to the corn crop, 

 and as we plow the corn stubble for oats and the oat stubble again for wheat, 

 the lime is first tin-ned under and then brought to the surface again before the 

 wheat is sown. 



We have now harvested three cro]>s of clover hay in this test, and in the 

 accompanying diagrams I have endeavored to show the general outcome. Dia- 

 gram I represents the seven-year average anmnil total weight of produce for 

 the cereal crops as found by taking one-third of the total weight of the three 

 crops, and Diagram II shows the thi-ee year average annu;il w(Mght of clover 

 hay on both the limed and imlimed halves of the plats. The first five years of 

 the test during which the land was l>eing bnmght under experiment are omitted 

 because of greater uniformity of the later results. 



These diagrams have been constructed by taking the average yield of all the 

 unfertilized plats as the basis and adding to this yield the increase found by 

 comparing the yield of each fertilized plat with those of the two unfertilized 

 plats between which it lies. 



The diagrams show that acid ]>hosi)hate. used alone or in combination with 

 potassium chlorid only, has produced a marked increase in the cereal crops, and 

 a similar increase in clover after liming, but in the absence of lime there has 

 been pi-actically no increase of clover from these fertilizers. It is noteworthy 

 that the small increase of unlimed clover after potassium chlorid disappears 

 when acid phosphate is added to the potassium, as shown by comparing plats 

 2 and 8. 



Taking the second section of each diagram, we see that incomplete fertilizers 

 containing sodium nitrate have i)roduced a uniform increase in both the cereals 

 and clover, both with and without lime, the point of interest being the much 

 larger yield of unlimed clover on these plats than where the nitrate has been 

 omitted. 



The third section of each diagram shows the yields from the complete ferti- 

 lizers containing sodium nitrate, which is added at the rate of 480 pounds i)er 

 acre for every rotation excei)t on plat 12, where the quantity is increased to 

 720 pounds. Comparing these plats with No. 6. which receives 480 pounds of 

 sodium nitrate with acid phosphate but no potassiiun. we see that the addition 

 of potassium has evidently increased the yield of the cereals, and still more 

 evidently that of the unlimed clover. Comparing with plat 8. which has phos- 

 phorus and potassium. ])ut no nitrate, we see that whereas the unlimed clover 

 on that plat has made no increase, the limed clover very nearly equals the yield 

 obtained from the complete fertilizer. In other words, the combination of lime, 

 phosphorus, and potassium seems to have brought the clover crop to perfection 

 without the addition of any nitrogen carrier, whereas the cereal crops show very 

 plainly the need of nitrogen. Other points of special interest brought out by 

 this section are (1) that the further increase of sodium nitrate on plat 12 has 

 apparently produced no further increase of the unlimed clover, though a small 

 additional increase is shown on the cereals and the limed clover: (2) that the 

 bone-meal plat. No. 26, while materially below the average in cereal yield, shows 

 a full yield of clover, and (3) that the plat receiving dissolved l)oneblack, No. 

 27, while giving a full yield of cereals and of limed clover, falls below in the 

 yield of unlimed clover. While the diagram shows a slightly greater weight of 

 hay on the unlimed end of plat 11 than on that of plat 26, the fact is that in two 

 years out of the three the yield was considerably larger on plat 26, indicating 

 that the apparently smaller yield on this plat in the average is due to a variation 

 in soil conditions. 



The last section of each diagram shows for the cereals an almost uniform yield 

 for the difEereut carriers of nitrogen, and a fairly uniform yield of the limed 



