Plant densities, yields and area demands for maize under shifting cultivation in the Chinantla, Mexico

Shifting cultivation is still widely practised for subsistence production of maize in Mexico. The related area demands diminish the area available for conservation goals. Increase of maize yields per hectare may reduce these area demands. In this article the relation between plant densities and yields in maize under shifting cultivation on steep slopes in Santa Cruz Tepetotutla, Oaxaca, Mexico, is analyzed in order to determine if higher plant densities can increase yields. Two complementary data sets were obtained from milpas where farmers applied their usual plant densities. On the milpa scale, the average number of plants and plant holes, and yield per hectare was calculated from sample plots in 12 milpas in 1993 and 15 in 1994. On the scale of plant holes, the numbers of plants and grain weight was determined at 40 individual holes in 14 milpas in 1994. Milpa scale data showed that yields are positively correlated with the number of plant holes per hectare. The mixed effects model for plant hole, data showed an increase of yield with the number of plants per hole, and produced a breakdown of random variability in yields between milpas. The results indicate that application of a density of 7000 plant holes per hectare, all with six plants, could increase yield by 20% and reduce area requirements for maize subsistence crops. It is recommended that the increased plant densities be integrated as a good practice in farmers' strategies to enhance resource efficient land use.