i?o. 1 DEPARTMENT OF AGRICULTURE. 599 



houses was made up of two parts clay loam, which contained a 

 fair amount of organic matter and available plant food, one part 

 muck and one part stable manure. It will be necessary, no doubt, 

 to add more muck from time to time in order to keep the soil mel- 

 low and in a good physical condition. 



It is only in rare instances that soils are renewed in vegetable 

 forcing houses. Several years ago 1 saw a crop of lettuce growing 

 in soil which had been in continuous use for thirty years and the 

 crop I saw was a very good one. So far as 1 know this soil is still 

 in the houses. In most cases the greenhouse soil is kept in a pro- 

 ductive state by the addition of large quantities of well rotted stable 

 manure which is spaded into the soil just previous to the planting 

 of each crop. The Ohio Experiment Station and a few growers in 

 the state have for several years followed another plan of renewing 

 the soil fertility. Briefly the plan is as follows: As soon as the 

 tomato or cucumber vines are removed from the houses, about 

 August fifteenth, a heavy coat of manure is spread upon the soil. 

 Water is applied at frequent intervals, once or twice a week, and 

 in sufficient quantity to leach the fertility out of the manure into 

 the soil. Just before the first crop is planted the coarser part of the 

 manure is removed and the finer worked into the soil. No more 

 manure is added to the soil until the tomato or cucumber crop is to 

 occupy the ground when well rotted manure is worked into the soil 

 or coarser manure applied as a mulch. Thus two or three crops 

 of lettuce are grown with but one application of manure. This is 

 the plan we follow and we have found it very satisfactory. 



As a general thing little or no commercial fertilizer is used in 

 vegetable forcing houses. Tests which were conducted by the Ohio 

 Station demonstrated that commercial fertilizers can be used to 

 supply the plant food in greenhouse soils but it is necessary to 

 supplement them with some form of organic matter. Manure or 

 muck being suitable for this purpose. When stable manure which 

 has not been exposed to the weather can be secured in sufficient 

 quantity without too great an outlay there is little use made of com- 

 mercial fertilizers for greenhouse work. There is need, however, 

 of further investigation by our Experiment Stations and others to 

 determine when and in what quantities commercial fertilizers can 

 be used to advantage in vegetalble forcing houses. 



Lime has been used with good results in some cases. We save 

 all of the ashes which result from the burning of the tobacco stems 

 and work them into the soil. 



Soil sterilization has been foimd necessary in many of the com- 

 mercial houses. Steam has given best results although formalin 

 has been used successfully in some cases. The outfit for sterilizing 

 with steam should consist of a steam boiler with connections to per- 

 forated pipes buried in the soil to be treated. The soil is not moved 

 from the beds or benches but treated where it is in use. The 

 steam is forced into the pipes under pressure and the pipes are not 

 removed or moved until the soil is literally cooked. Where sub- 

 irrigation is used the steam is turned into the tile for sterilizing the 

 soil. Some of the Ashtabula growers use muck in which to start 

 the seedling plants. The muck is placed in a box through which 

 perforated pipes are run, the steam turned on and the soil sterilized 



