816 EXPERIMENT STATION IlECORD. [Vol.38 



soluble salts are in excess and iininodlately become active wlien the excess of 

 salts is removed. 



" The method adopted is not to attempt a count of the organisms present, 

 but to measure tlieir cliemical activity under standard conditions. Tliis in- 

 volves the measurement of the rate of carbon dioxid formation, the rate of 

 nitrification of ammonia botli in a nutrient solution and in the soil, and the 

 rate of nitrogen fixation. Tlie figures so obtained give an index to tlie num- 

 ber and condition of the bacteria responsible for these important processes or 

 will, in other words, be an indirect measure of the decrease in the osmotic 

 pressure of the soil water, using for the test not merely one type of organism 

 but all those responsible for the three chief chemical reactions necessary to the 

 full fertility of the soil." 



Some observations on the occurrence of infertility under trees, Jatindra 

 Nath Sen (Agy. Jour. India, 12 (1011), No. 3, pp. SUO-JfOo, pis. 5; abs. in CJiem. 

 Abs., 11 {1911), No. 22, p. 307S). — Data are presented from observations on the 

 occurrence of infertile spots under tamarind trees and bamboo clumps. They 

 indicate that, wMle numerous factors were perhaps involved, the infertility 

 in these particular cases was due mainly to the accumulation of soluble salts 

 accelerated by the great transpiring power of the plants whicli removed the 

 soil moisture, leaving behind the greater part of the solnl)le salts. 



Results of fertilizer experiments conducted at the Pee Bee Station, T. E. 

 Keitt {South Carolina Sta. Bui. 198 {1917), pp. 3-2.'/). — Rather extensive fer- 

 tilizer experiments in progress at the Pee Dee substation are described, and 

 the results obtained from the first rotation (1914 to 1916, inclusive) are re- 

 ported. The experiments embrace four series each containing 45 tenth-acre 

 plats. Three series consist of 3-year rotations of corn and cowpeas, oats 

 followed by cowpeas, and cotton, and the fourth series of cotton grown continu- 

 ously. Detailed tabulated data are presented and discussed, showing the yields 

 obtained with each crop under the different fertilizer treatments, and com- 

 parisons are made of the effects of the different fertilizer ingredients used 

 singly and in combination. The results in general are regarded as tentative. 

 The more or less definite conclusions may be summarized as follows : 



The addition of potash to phosphorus on this soil was beneficial in most 

 cases where the rotation was used, but had little if any effect where cotton 

 was grown continuously. Nitrate of soda used as a top-dressing gave good 

 results generally when applied to cotton, both when grown continuously 

 and in rotation, the results indicating that nitrogen is the first limiting factor 

 in cotton production. Very little benefit was gained through the application 

 of either muriate of potash or kainit alone, although marked increases of seed 

 cotton were obtained from a combination of nitrogen and potash on cotton 

 grown continuously. Neither ground limestone nor caustic lime proved to be 

 profitable on this soil in either the common 3-year rotation or where cotton 

 was grown continuously. Applications of lime failed to give increased yields 

 of cotton even when a heavy growth of cowjjea vines was incorporated with 

 the soil. The best time for plowing under eo-\\T)ea vines appeared to be after 

 the peas were picked, rather than at the time of most luxuriant growth. 



A simple way to increase crop yields, H. A. Miller {U. S. Dept. Agr., 

 Farmers' Bui. 92Jf {1918), pp. 2Jf, figs. 10). — Cropping conditions on the im- 

 poverished light soils of the Coastal Plain area of New Jersey, Maryland, Dela- 

 ware, and Virginia are described. The principal need of the region is said to 

 be a liberal supply of organic matter obtained chiefly through the growing of 

 leguminous crops such as crimson clover, cowpeas, soy beans, red clover, and 

 hairy vetch ; and of rye, buckwheat, or suitable grasses. Commercial fertilizers 

 and lime are recommended when necessary to stimulate the growth of the soil- 



