19161 SOILS — FERTILIZERS. 125 



Cylinder experiments relative to the utilization and accumulation of 

 nitrogen, J. G. Lipman and A. W. Blair {New Jersey Stas. Bui. 289 (1916), pp. 

 3-88, figs. 18). — Seven years' experiments with a 4-year rotation of corn, pota- 

 toes, oats, and rye on two types of sand, fine sand, two types of sandy loam, 

 two types of loam, and gravelly loam soils are reported, the purpose of which 

 was to determine the relative value of the nitrogen of sodium nitrate, green 

 manure crops, and stable manure. The sodium nitrate was used at the rate of 

 160 lbs. per acre, green manure crops consisting of crimson clover, vetch, soy 

 beans, and cowpeas were seeded after each main crop, and stable manure was 

 used at the rate of 15 tons per acre applied once in two years. 



" The fertilizer treatment provides for two cylinders each without any fer- 

 tilizer, two with minerals only, two with minerals and nitrate of .soda, two 

 with minerals and green manure, and two with minerals and stable manure, for 

 each type of soil. All soils received a treatment of ground limestone when the 

 experiment was begun, and similar applications at the end of each 5-year 

 period." 



Determinations of soil nitrogen after 5 years showed that " there has been 

 a gradual depletion of the nitrogen content of the soil for six out of the eight 

 types, even where nitrogenous fertilizers have been applied and where green 

 manure crops have been grown. The soils from the check cylinders show the 

 lowest percentage of nitrogen. The soils from the cylinders which receive 

 minerals only and those which receive minerals and nitrate of soda show 

 essentially the same percentage of nitrogen. The soils from the cylinders 

 which receive minerals and green manure, and from those which receive 

 minerals and stable manure, likewise show practically the same percentage of 

 nitrogen, and this amount is about 0.01 per cent higher than in those cylinders 

 where minerals only and minerals and nitrate of soda are used. It thus appears 

 that the green manure crops have been quite as effective in maintaining the 

 nitrogen supply of the soil as stable manure at the rate of 15 tons per acre 

 applied once in two years. . . . 



" The unfertilized cylinders gave the lowest yield of dry matter and nitrogen, 

 and those that received minerals only the next highest. The cylinders that 

 received minerals and nitrate of soda gave a higher yield of dry matter and 

 nitrogen than those that received minerals only. . . . The highest yields of 

 nitrogen and dry matter were from cylinders where green manure crops have 

 been grown, and the next highest from those where stable manure has been 

 used." 



Calculation of the percentages of nitrogen recovered from sodium nitrate 

 and stable manure showed that " in most cases this recovery was low for both 

 the nitrate and the manure. The average recovery for nitrate for the 7 years 

 was 39.59 per cent and for the manure it was 11.04 per cent. . . . 



" Of the different types of soil the Norfolk sand gave the lowest yield of dry 

 matter and nitrogen and the Quinton sandy loam the highest yield. The Penn 

 loam stands next to the Quinton sandy loam. ... On the Norfolk sand and 

 Elsinboro fine sand the nitrogen supply of the soil has just been maintained by 

 the use of green manure and stable manure. On the other six types the nitrogen 

 supply is now less than when the experiment was begun, even where green 

 manure and stable manure have been used. 



" Since the yields with the green manure have, on the average, been greater 

 than with stable manure, and since the nitrogen supply of the soil has been 

 maintained on a level with that on the stable manure cylinders, it seems fair 

 to conclude that the green manure crops have furnished at least as much nitro- 

 gen each year as the stable manure, and . . . that a small or moderate green 



