Prehistoric Mogollon agriculture in the Mimbres River Valley, southwestern New Mexico : a crop simulation and GIS approach

A crop simulation program, CERES-Maize 2.1 in the Decision Support System for Agrotechnology Transfer Version 3.5, is used to model and evaluate prehistoric maize agriculture in the Mimbres River Valley of southwestern New Mexico. The crop simulation is used to evaluate planting dates and planting densities for maize and to evaluate the usability of soils in the study area. Then, optimal planting dates and planting densities are used to compute production for the historic period of 1958 to 1993 for which there is climatic data. These production amounts are used to determine sustainable population levels in the study area for these years. A stepwise multiple regression analysis using the dendroclimatologically reconstructed variables precipitation from previous August to current July (AUGJULPRECIP), precipitation from previous October to current May (OCTMAYPRECIP), current June PDSI (JUNEPDSI), June PDSI from previous year (PDSI_YR_1), previous year’s October to May precipitation (OCTMAY_YR_1), and previous year’s August to July precipitation (AUGJUL_YR_1) against sustainable population estimates for the years 1958 through 1988 is run. Using the resulting regression equation, sustainable population levels are estimated for A.D. 950 through A.D. 1200. These sustainable population levels are then compared to estimated population based on an exponential growth model. The data indicate that agricultural production is more than adequate to support the estimated population throughout the time span with enough surpluses for at least two years consumption. It is determined that agricultural stress due to inadequate precipitation is not responsible for the collapse of the Classic Mimbres.