Studies on the Effect of Nitrogen, Phosphorus, and Potash on the Yield of Corn and Wheat in Mexico

is the most important single crop in Mexico. V^« For the 5-year period of 1940-44, 55% of the arable land was devoted to it (a). In value, the corn produced in Mexico is approximately equal to that of the following ten crops combined: Wheat, beans, potatoes, sweet potatoes, rice chili, chickpeas, peanuts, barley, and alfalfa. For the 5-year period of 1939-43, its value was more than that of cotton and sugar cane combined (2). But "far more important than its monetary value is the role it plays in the nutrition of the people. It is the basic food crop for nearly 20 million people, who, from it, prepare a wide variety of dishes, such as tortilla, atole, pozole, tamales, and elotes cocidos. Each year a tremendous amount of energy goes into producing Mexico's 8% million acres of corn. In spite of this, however, Mexico is on an import basis, -for the average 'yield is only 9.6 bushels per acre (i, 2). To raise the corn yield of Mexico is to raise the level of nutrition of these 20 million people whose well-being depends quite largely upon the season's corn crop. Wheat is also of major importance as a food crop. Since Mexico imports roughly 30% of the total consumed in the Republic (around 190,000 tons annually), any program designed to raise the level of production of this crop might well be expected to affect not only the diets of some 20 million people but also the national economy as. well. For the 5-year period 1940-44, Mexico spent, for the purpose of importing wheat, an amount of money greater than the value of all Mexican-grown beans, one of the . crops for which she is world famous (i, 2). Wheat is almost entirely an irrigated crop. Relatively speaking cultural practices are poorer than they are for corn. Well-planned crop rotations and commercial fertilizer are the exception. Average yields are very low. In an attempt to develop practical methods useful in raising the level of corn and of wheat production in Mexico, the Secretary of Agriculture of that Republic, in an agricultural research program supported in part by the Rockefeller Foundation, is devoting special attention to these crops. Among the aspects receiving study in the general program are the problems of soil fertility. The present report is concerned with this phase of the corn and wheat improvement programs. In it are presented the first year's results from, the use of commercial .nitrogen, phosphorus, and potassium in field experiments. The study, was based on certain established and wellknown facts pertaining to the problems of corn and wheat fertilization already worked out by other investigators, and its objective was that of studying the application of these principles to Mexican agriculture rather than that of studying fertilization of those crops per se. Experiments were conducted in cooperation with private farmers and on government lands under the control >of the Secretary of Agriculture during the 1944-45 season. The techniques employed, as well as the results obtained, are discussed in subsequent sections of this paper.