The effect of sewage irrigation has been found to be most astonishing so far as the increased yield of the soil goes. Some years ago, in order to determine just the effect of the addition of sewage to ordinary farm land, a certain field of five acres was divided into four equal parts. The four fields were treated as follows: Field No. 1 received no sewage. Field No. 2 received six inches of sewage over its entire area on each of five successive months. Field No. 3 received twelve inches of sewage on each of five successive months. Field No. 4 received eighteen inches of sewage on each of five successive months. The following table shows the results of three successive years’ experiments at the sewage farm referred to at Rugby, England, the figures being the number of pounds of green grass cut from the fields. FIVE-ACRE FIELD ═════════════════╤═════════════════════════════════════════════════════ WITHOUT SEWAGE. │ WITH SEWAGE. ─────────────────┼─────────────────┬─────────────────┬───────────────── Lot 1. │ Lot 2. │ Lot 3. │ Lot 4. ─────────────────┼─────────────────┼─────────────────┼───────────────── 20,814│ 33,244│ 60,602│ 73,564 18,294│ 62,514│ 77,299│ 71,766 11,069│ 49,851│ 78,231│ 80,941 ─────────────────┼─────────────────┼─────────────────┼───────────────── Aver. 16,725│ 48,536│ 72,044│ 76,434 ─────────────────┴─────────────────┴─────────────────┴───────────────── It will be noticed that, whereas without sewage the amount of green grass was about eight tons on an acre and a quarter in the field, from lot No. 2 twenty-four tons were cut, from lot No. 3 thirty-six tons, and from lot No. 4 thirty-eight tons. Evidently the amount of sewage applied did not proportionately increase the yield in lots 3 and 4, and it may be said that a depth of sewage or water of more than twelve inches per acre has, in general, been found to be not merely unnecessary, but undesirable. The table does not show the number of cuttings made during the season, but the custom on the farm is to cut frequently, at intervals of perhaps two or three weeks, no time being given for curing the hay.