Wednesday, November 15, 2006
297-5
Mixed-Species Agroforestry Systems in the Humid Tropics of Brazil: Soil Impacts and First-Year Growth.
Aaron H. Joslin, Daniel Markewitz, and Lawrence Morris. U. of Georgia, 215 China St, Apt 205, Athens, GA 30605
In the State of Par�, Brazil, nitrogen (N) fixing trees have been shown to increase the biomass produced during fallow, which increases the nutrient availability to crops and/or plantation forest species during successive cropping periods. Recuperation of degraded agricultural lands In Par�, Brazil through the use of agroforestry systems that use native nitrogen (N)-fixing trees has the potential to increase economic output from small farms by improving N availability and diversifying production. Sixteen 24 x 24m plots were planted in a split-split plot design (species x P fertilizer x N fertilizer) with 76 trees per plot and three rows of manioc planted between each row of trees at 1m x 1m spacing. Four native, non-fixing species S. amazonicum, C. pentandra, C. odorata, P. multiujga and one native N-fixing species, I. edulis were planted. Two planting schemes were used with fertilizer (P+) and without fertilizer (P-); 1). Inga edulis with the other four species (N+) and 2). 3 non-fixing species S. amazonicum, C. pentandra and C. odorata (N-). Soil analyses were completed and tree growth determined after one year.After one year, fertilized plots had higher mortality in all species compared to non-fertilized plots; 65% in P+ plots and 14% in P- plots. In fertilized plots, only S. amazonicum had significantly greater average GLD, DBH and Height in plots grown with I. edulis than without. Mean height of S. amazonicum was 552cm with 51% mortality in fertilized plots with mean height of 107cm and 36% mortality in unfertilized plots. Mean height of I. edulis was 175cm with 1.3% mortality in unfertilized plots and 291cm with 48% mortality in fertilized plots. .
Handout (.ppt format, 16618.0 kb)