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 Pará, 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 Pará, 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)