PRACTICAL INFERENCES. 119 
thus, in the case of wheat, the average produce per acre 
over thirty years, was about thirteen bushels on the 
unmanured plots, as against thirty-six on highly manured 
plots (mineral and ammonia salts, and mineral and 
nitrate respectively), some plots also producing the largest 
quantities of straw, the nitrate producing rather more 
than the ammonia. The quality of the produce of wheat 
as measured in pounds per bushel is not so different, 
that on the unmanured plots being usually nearly equal 
to that of the highly manured plots. From this point of 
view, farm-yard manure proved more beneficial than the 
artificial nitrogenous and mineral manure yielding the 
largest quantity of grain. The corresponding figures in 
the case of barley, are seventeen and forty-nine ; the 
highest produce was with nitrate and. minerals, but the 
largest amount of straw was yielded with a manure con- 
taining a large proportion of nitrate of soda with 
minerals. Of hay, the average produce under like cir- 
cumstances over twenty years, was two thousand three 
hundred and fifty two pounds on the unmanured, and 
six thousand nine hundred and forty-four pounds on 
highly manured plots (mineral and ammonia.) 
In like manner, turnips varied from one or two tons per 
acre without manure to eight tons with superphosphate, 
and nine to twelve tons with superphosphate combined 
with nitrogenous manure, such as ammonia or rape-cake. 
Sugar beet produced, when unmanured, from seven to 
eight tons per acre in the earlier, to five tons in the later 
years, but eighteen tons with farm-yard manure ; nitro- 
genous manures increased the yield largely, but super- 
phosphate was of no use to the beet and mangel. With 
mangel, the produce on the unmanured plot was from 
one to six tons per acre (average 4.6 tons), as compared’ 
with nineteen tons with farm-yard manure (or on the 
average fourteen tons). Potatoes varied from about half 
a ton on the unmanured, or about two tons on the 
