In cases of this kind, an annual application of manure is absolutely necessary; and we are happy to find that different manures and their effects have been experimented upon and duly noted, _for the same plots_, during a period of no less than twenty years, and that by such careful and reliable inquirers as J. B. Lawes, Esq., F.R.S., and Dr. Gilbert, F.R.S.; full details of the results of whose labours upon this subject will be found in Vol. XXV. of the _Journal of the Royal Agricultural Society of England_, from which we have extracted some of the following general conclusions as to average yield and weight of corn for the lengthened periods quoted:— 1. TABLE OF RESULTS OF EXPERIMENTS AT ROTHAMSHEAD, BY MESSRS. LAWES AND GILBERT. +------+--------------------------+------------+---------+----------+ | | | | Average | | |Plots.| Manures used every year. | Average. | weight | Years. | | | | |per bush.| | +------+--------------------------+------------+---------+----------+ | | |Bush. Pecks.| | | | 1 |Unmanured every year | 16 1 | 57·9 | 20 years,| | | | | | 1844-63. | | 2 |Ammonia salts alone | 24 1¾ | 57·6 | 19 years,| | | | | | 1845-63. | | 3 |14 tons Farmyard manure | 32 1¾ | 60·0 | 20 years,| | | | | | 1844-63. | | 4 |Unmanured every year | 15 2 | 56·5 |} | | 5 |Mixed mineral manure alone| 18 1¾ | 57·9 |} | | 6 |Ammonia salts alone | 22 2½ | 55·9 |}12 years,| | 7 {|Ammonia salts and mixed } | | |}1852-63. | | {|mineral manure } | 36 1½ | 58·4 |} | | 8 |14 tons Farmyard manure | 35 1½ | 59·3 |} | +------+--------------------------+------------+---------+----------+ A glance at this table shows us the wonderful results of _continuous_ manuring for the soil operated upon; we might, however, expect that, though the general conclusions would probably not greatly vary, yet that there would not be absolute uniformity in these respects in different soils and districts.