228 EXPERIMENT STATION RECORD. [Vol. 41 



Great Divide, Burbanli, and Peerless potatoes have produced maxiuiuiu 

 average yields for a 5-year period of 13,540, 12,091 and 11,782 lbs. per acre, 

 respectively. Our Ideal mangel produced the highest average yield, 30,469 

 lbs. per acre, for a 4-year period in a comparative test of different varieties 

 of beets, but is deemed inferior in feeding value to sugar beets which pro- 

 duced at the rate of 25,907 ll)S. for a 3-year period. In date-of-plantiug tests 

 ■with sugar beets the best results were secured from plantings made before 

 the first of May. 



[Report on the activities of the agricultural association of Zealand, Den- 

 mark, in 1918], A. P. Jacobsen (Bcr. Landhofor. Tirks. rhinteavl. HjaUand, 

 1918, pp. 551, pis. 8, figs. 2). — The activities reported on included cooperative 

 experiments with fertilizers and lime, rotations and fallows, variety tests of 

 different field crops, examination and testing of seeds, studies of methods 

 of weed destruction, and determination of the nitrogen content of fertilizers. 

 The report presents also the proceedings of the meetings of the association, 

 together with a discussion of the association's work in general. The condi- 

 tions affecting agriculture during the year are briefly noted. 



In fertilizer experiments conducted with cereal crops from 100 to 200 kg. 

 of nitrate of soda per hectare (about 89 to 178 lbs. per acre) were used, alone 

 or in combination with 150 to 300 kg. of superphosphate or with this amount 

 together with 100 to 150 kg. of 37 per cent potash salt. It is calculated that 

 to defray the cost of the fertilizers 100 kg. of nitrate of soda had to produce 

 an increase in yield of 160 kg. of grain and 1,600 kg. each of roots and grass ; 

 100 kg. of 18 per cent superphosphate, 100 kg. of gi-ain and 1,000 kg. each of 

 roots and grass; and 100 kg. of 37 per cent potash salt, 72 kg. of grain and 720 

 kg. each of roots and grass. 



A series of experiments was conducted with rye, barley, oats, and root crops 

 on clay soils. The average results of five experiments with barley after another 

 grain crop indicated an increase of 207 kg. of grain iind 282 kg. of straw from 

 the use of 100 kg. of nitrate of soda, and the improfitable use of an addition 

 of 100 kg. of superphosphate or of 100 kg. each of superphosphate and potash 

 salt. The average results of 12 similar experiments with barley following root 

 crops showed an increase of only 142 kg. of grain and 308 kg. of straw from 

 the use of 100 kg. of nitrate of soda per hectare, and also an unprofitable use 

 of either superphosphate or superphosphate and potash salt in addition. The 

 plants receiving no fertilizers and on which barley was grown after another 

 grain crop produced in 1918 an average of 2,088 kg. of grain and 2,426 kg. of 

 straw per hectare, as compared with 2,409 kg. of grain and 2,884 kg. of .straw, 

 where the barley followed root crops. 



The use of 100 kg. of nitrate of soda in growing oats gave a profitable in- 

 crease only where the oats followed grass. 



The average results of 21 experiments with mangels following different crops 

 showed an increase of 3,200 kg. where 100 kg. of nitrate of soda had been ap- 

 plied. The addition of 100 kg. of superphosphate -was profitable in only nine 

 of the experiments, and the average results were also unsatisfactory. The ap- 

 plication of 100 kg. of potash salt together with superphosphate gave, on the 

 average, profitable returns. The results from the use of superphosphate and 

 potash salt varied to a marked extent. 



In a limited mimber of fertilizer experiments with grass grown for seed, it 

 was found th.-it nitrate of .soda and potash salt applied to land in Italian rye 

 grass gave satisfactory average increases in yield. 



For three years nitrate of soda at the rate of 100 kg. per hectare was us(><l 

 alone and in combination with a complete application, including a like amount 

 in growing barley and oats, In 1918 a large increase in yield was secured 



