182 



The Rothamsted Grass Experiments. 



nitrate of potash would be more or less effective than a 

 mixture of nitrate of soda and sulphate of potash, the 

 mixture containing the same amounts of nitrogen and 

 potash as the nitrate of potash. In 1872, plots 19 and 20 

 were set apart for this test. In each of the seven years, 

 1872-78 (and the experiment is still in progress), plot 19 

 received 2751b. nitrate of soda, and plot 20 3271b. nitrate 

 of potash, both containing the same weight of nitrogen. 

 Plot 19 also received 2901b. sulphate of potash, containing 

 the same weight of potash as the 3271b. nitrate of potash. 

 Each plot has also received annually 3i cwt. superphosphate 

 of lime. For comparison there is given in Table XLV. the 

 average produce over the same seven years, and also over the 

 preceding fourteen years, on plot 16, manured annually, 

 during the whole period of twenty-one years, with 2751b. 

 nitrate of soda, 3001b. sulphate of potash, lOOlb. sulphate of 

 soda, lOOlb. sulphate of magnesia, and 3| cwt. superphos- 

 phate of lime. The quantities of manures on each plot are 

 not repeated in the table. 



TABLE XLV. AVERAGE PER ACRE PER ANNUM, BY NITRATE OF SODA 

 AND SULPHATE OF POTASH, AND BY NITRATE OF POTASH, CONTAINING 

 EQUAL NITROGEN AND EQUAL POTASH, IN EACH CASE WITH SUPER- 

 PHOSPHATE; PLOTS 19 AND 20. 



Per Acre per Annum. 



