BP BULLETIN 1458, U. S. DEPARTMENT OF AGRICULTURE 
LITERATURE CITED 
(1) Brpwex1, P. W., and Fatconsr, J. I. 
1925. HISTORY OF AGRICULTURE IN THE NORTHERN UNITED STATES, 1620— 
1860. 512 pp., illus. Washington, D. C. (Carnegie Inst. 
Wash. Publ. 358.) 
(2) ERNLE, LORD 
1921. THE ENCLOSURE OF OPEN-FIELD FARMS. sour. Min. Agr. [Gt. Brit.] 
27: 899-911. 
(3) FRANCE, MINISTERE DE L’ AGRICULTURE. 
1919. STATISTIQUE AGRICOLE ANNUELLE, 1917. 420 pp. Paris. 
(4) Gray, L. C., and others. 
1924. UTILIZATION OF OUR LANDS FOR CROPS, PASTURE AND FORESTS. 
U. S. Dept. Agr. Yearbook 1923: 415-506, illus. 
(5) Great BRITAIN AGRICULTURAL TRIBUNAL OF INVESTIGATION. 
1924. FINAL REPORT. 405 pp. . London. 
(6) Howarp, A. 
1924. CROP PRODUCTION IN INDIA. 200 pp. London 
(7) Marsut, C. F. 
1925. THE RISE, DECLINE, AND REVIVAL OF MALTHUSIANISM IN RELATION 
TO GEOGRAPHY AND CHARACTER OF SOILS. Ann. Assoc. Amer. 
Geog. 15: 1-29. 
(8) Nourse, EH. G. 
1919. THE PLACE OF AGRICULTURE IN MODERN INDUSTRIAL SOCIETY. I. 
Jour. Polit. Econ. 27: 466-497. 
(9) ProrHEro, R. BH. 
1917. ENGLISH FARMING, PAST AND PRESENT. Hd. 2, 519 pp. London. 
(10) Sarg, C. F. 
1924. IOWA CORN YIELDS. iowa State Dept. Agr., Mo. Crop Rpt., Apr. 
1924, pp. 10-20. 
(11) ScHREINER, O. 
1926. CHANGES IN CHARACTER, CONDITION, AND AMOUNT OF SOIL ORGANIC 
MATTER. Jour. Amer. Soc. Agron. 18: 115-126, illus. 
(12) WARREN, G. F. 
1914. CROP YIELDS AND PRICES, AND OUR FUTURE FOOD-SUPPLY. N. Y. 
Cornell Agr. Exp. Sta. Bul. 341, pp. 185-211, illus. 
(13) Wettz, B. O. 
1926. AN ANALYSIS OF CROP YIELD STATISTICS WITH REFERENCE TO SO{L 
DETERIORATION. Jour. Amer. Soe. Agron. 18: 90-106, illus. 
(14) WuHitNnry, M. 
1909. A STUDY OF CROP YIELDS AND SOIL COMPOSITION IN RELATION TO 
SOIL PRODUCTIVITY. U. /S. Dept. Agr., Bur. Soils. Bul. 57, 127 
pp., illus. 
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