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The chemical work required in connection with such a set of lysimeters demands a large part of one man's time.
When the tanks are first filled duplicate samples of the thoroly mixed soils are taken for each depth and for each of the two types; and complete analyses are made of these samples.
All fertilizers applied are sampled and analyzed.
Annual samples of the crops grown on each tank are analyzed for nitrogen, phosphorus, potassium, calcium, magnesium, sodium and total ash.
As the drainage water fills the receiving cans aliquot portions are saved and the remainder discarded. These aliquots are analyzed twice annually for phosphorus, potassium, sodium, calcium, magnesium, chlorine, sulphur, carbonates, bicarbonates, nitrates, nitrites and ammonia. In addition nitrates are determined every 2 to 4 weeks when tanks are flowing.
Samples of rain and snow water are examined for nitrogen.
CYLINDERS FOR OUT-DOOR POT CULTURE WORK.
When fertility experiments are conducted on soils under greenhouse conditions a much larger percentage of experimental error must be allowed for than under well-planned- field conditions. This is of course partly due to the very small quantities of soil used and consequently small amounts of crop grown under glass and also to the very artificial conditions imposed. Indeed, most common field crops can only with difficulty be brought to maturity under these conditions. Altho it would seem an opportunity to control accurately edaphic conditions, yet greater variations as regards temperature, moisture and sunlight are likely to occur at different places on the bench than on different plats in a carefully conducted field experiment. Also, soils having well known differences in productiveness in the field often show quite a different order of productiveness in the greenhouse.
The main advantage sought after in conducting fertility experiments under glass are: (1) Opportunity to make a large number of tests with little time and labor, (2) a chance to bring together under the same conditions different soil types, (3) avoiding the extremes of climatic conditions, (4) facilities for growing crops in the winter time, (5) means of controlling the exact amount and kind of plant food in the nutrient medium.
Up to date facilities for plant nutrition work arrange for having the plants out of doors all the time excepting at night and in inclement weather. As a step in advance of this many have tried having the pots or cylinders sunk in the ground and providing a movable covering.
After some experience with greenhouse experiments and after considering many methods used in pot-culture work, the author
has devised facilities for outdoor pot work as described herewith. They are intended to place the experiments under nearly natural conditions, yet allowing the use of definite amounts and types of soil, with soil composition and fertilizer treatment accurately known. When growing perennial plants, as desired in these experiments, it is necessary that seasonal changes operate as usual.
CONSTRUCTION OF OUT-DOOR CYLINDERS.
The accompanying drawing shows the construction of these cylinders without much need of explanation. Two glazed earthenware sewer pipes each 2 feet long and 3 feet inside diameter are sunk in the ground to within a few inches of the top, making a cylinder 4 feet in depth and holding, as filled, approximately 1400 pounds of silt loam soil. A trench is first dug about ten inches lower than the bottom of the cylinders and in this is laid a line of 3-inch drain tile, thus completely preventing the rise of ground water into the cylinders. To isolate the soil in the pot from the influence of the surrounding soil it is necessary also to break capillary connections and this is accomplished by a 4-inch layer of some coarse material. We have used hard coal of "pea" size, all gravel in this section being loaded with lime carbonates.
When the cylinders are filled the soil is placed in layers corresponding to the surface, subsurface, and subsoil in the field. The right amount of soil for a given set of cylinders is assembled on a barn floor, a separate pile for each stratum. Each pile is then shoveled over until there is no doubt of its uniform composition. Samples are taken for analyses and it is transferred to the cylinders. To give opportunity for settling over winter, the work should be done in the fall. The soil is only lightly tamped and the cylinders are filled to the top. Before treatment is begun the next spring the surface is smoothed to a level with the shoulder of the cylinder leaving a basin 3 inches deep to catch rain water and prevent loss of soil. Fertilizer applications are incorporated with the surface 4-inches, that amount of soil being transferred to a large receptacle for the mixing.
The bell-shaped top of the cylinder allows about 50 per ct. more rainfall than is normal for the surface of the soil exposed. And this is an important advantage considering the break in capillarity and also that on separated small areas of soil larger crops can be grown than is normal to the same area in a crowded field. Lack of sufficient moisture should not be a limiting factor in this work and so it is advisable at times to water the pots by hand. For this purpose there should be a reservoir of rain water near by with piping to the vicinity of the pots. This precaution applies also to the lysimeters.
Cylinders In Operation.
The first set of these cylinders were constructed at this Station in the fall of 1914. Another set were prepared in November, 1915, making a total of 98, each 4 feet deep. Of these 48 are given over to a fertility study with peach trees, and 50 others are used in lime requirement studies, alfalfa being grown on one series and rape being the first crop on another series. The soils used in these cylinders are of two types, the same as those used in the lysimeters, and have been taken from the same localities. All but 18 of the cylinders are filled with the southern New York soil high in lime requirement.
DETERMINATION OF CARBONATES IN LIMESTONE AND OTHER MATERIALS.*
J. F. BARKER.
This bulletin describes and illustrates a simple device for the determination of carbonates, particularly in limestones and similar materials. It is based on the principle of the hydrometer, requires no weighing and gives results without computations. From its inexpensiveness, simplicity and accuracy it should serve a useful purpose in a wide field.
RELIABILITY AND PRINCIPLE OF APPARATUS.
Results obtained in the determination of carbonates by the apparatus herein described compare favorably with results from the use of any standard laboratory method. The advantages of this method over others are that no chemical balance or scale is required and that there are no long calculations to be made. Anyone with some aptitude for accuracy can, with this instrument, make as reliable a determination in home or office as a skilled chemist in a well equipped laboratory using complicated apparatus. *
The invention depends upon the principle of the hydrometer, which takes account of the law that when an object is immersed in a liquid it is buoyed up by a force equal to the weight of the liquid displaced by the object. In the apparatus the carbon dioxide gas set free from the sample decreases the weight; and the rise of the graduated scale tube above the water records the percentage of carbonates from which the gas was released.
To analyze a sample of limestone for carbonates: Measure out 40 c.c. of HC1 (sp. gr. 1.15) using a small graduate; pour this into the acid reservoir through the opening at A. With graduated stem disconnected hang 10-gram weight at B. The hydrometer should then float in a cylinder of water and be immersed to some point at C. Remove 10-gram weight and introduce pulverized limestone until instrument is immersed to exactly the same point. Now connect graduated stem and add water, a drop at a time, through
* Reprint of Technical Bulletin No. 62, May, 1917.