Different Soil Test Methods Applied to Soils of Known Fertilizer Treatments

During the past few years New Jersey farmers have become more and more soil conscious. This has been brought about primarily by the production of specialized crops, the variety of crops grown, the length of time in which our soils have been under cultivation, the active soil-forming processes in this region, and the variety of soil types in the state. For many years research workers at the station have been active in studying soil fertility problems. The methods employed have been the use of field plots, cylinders, and precise chemical methods. With the advent of rapid soil tests, considerable interest was created and various soil test methods were employed by commercial and station workers as a criteria for the needs of fertilizer and liming material applications. The results of this work were very gratifying and the subsequent publicity created a demand for a soil testing service. To meet this demand a service was established in July 1935. From this date to November 1, 1937, 11,831 soil samples have been tested for their pH value. 10,864 samples have been tested for readily available nitrate and ammonia nitrogen, phosphorus, potash, calcium, and magnesium. Easily soluble aluminum, iron, manganese, chlorides, and sulphates have, also, been run on these samples. In addition to the afore-mentioned tests, 5,590 determinations have been made for readily oxidizable organic matter. The above figures represent only those samples submitted by residents of the state through the various County Agricultural Agents, Extension Specialists, or directly to the Experiment Station. 1,162 additional samples have been tested for their pH value, 1,018 samples for readily extractable soil constituents, and 231 samples for their organic matter content. Most of these samples have been collected from various research projects, the results of which have been tabulated and published in part (6) for the purpose of calibrating soil tests in order to determine the relationship between rapid soil tests and crop responses. The requests for soil tests in New Jersey are steadily Increasing. This is in evidence when the contents of Table 1 are observed. This table lists the total number of samples, as well as the average number of samples tested monthly for pH, readily available nutrients and organic matter since the establishment of the service. During the first six months of testing the average number of samples tested each month was 204. During the next year we tested on an average of 364 samples each month. Since January 1, 1937 the number of samples tested each month had increased to 527. At the outset of the New Jersey Soil Testing Service, the Morgan (13) "Universal System" was adopted. It was found, however, that certain modifications in the procedure