. Proceedings of the American Society of Agronomy . -burg, Germany, and used by Hellriegel.^ The cans were mounted on heavy cars and pushed in and out of theplant house on a track. A somewhat similar plant house was usedby Widtsoe at the Utah Experiment Station.* In these cases, how-ever, evaporation from the surface of the soil was not prevented, andit is also known that water loss from the plant would be greatly re-duced by putting the plants in a house as compared with leaving themin the open, under field conditions. With these sources of errorrecognized, there has been need for an apparatu
. Proceedings of the American Society of Agronomy . -burg, Germany, and used by Hellriegel.^ The cans were mounted on heavy cars and pushed in and out of theplant house on a track. A somewhat similar plant house was usedby Widtsoe at the Utah Experiment Station.* In these cases, how-ever, evaporation from the surface of the soil was not prevented, andit is also known that water loss from the plant would be greatly re-duced by putting the plants in a house as compared with leaving themin the open, under field conditions. With these sources of errorrecognized, there has been need for an apparatus which could be left Exp. Sta. Rec, Vol. V, No. Exp. Sta. Bnl. 105. 2/0 PROCEEDINGS OF THE AMERICAN SOCIETY OF AGRONOMY. in the open under field conditions which would exclude rainfall onthe one hand and evaporation on the other, and at the same timepermit a plant to mature normally. Fig. 46 illustrates a can devisedat the Nebraska Experiment Station for this purpose. The can is36 inches deep but could be made larger. A ^ inch copper coil,. Fig. 45.—Plant house and trucks used in moving cans at Bernburg (Germany)Experiment Station. (Exp. Sta. Rec, Vol. V., No. 8.) perforated every 8 inches, is placed in the can. Over each perfora-tion a small piece of sponge is tied. Water is added by pouring thedesired amount into a can attached to the upper end of the method of distributing the water has several advantages. Inthe first place, it is uniformly distributed throughout the mass ofsoil. This is very important, especially where it is desired to keepthe water content rather low. Experiment showed that when waterwas added it would distribute itself in a fairly uniform mannerthroughout the soil mass in about two hours. If the watering wasdone in the evening, plants requiring very little water during thenight, the soil would be very uniformly moistened by morning. Thecoil also serves to aerate the soil. It has generally been found diffi-cult to grow a plant to matu
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