Effects of land-clearing method and soil management on crop production in the Amazon

Abstract

Alegre, J.C., Cassel, D.K. and Bandy, D.E., 1990. Effects of land-clearing method and soil manage­ ment on crop production in the Amazon. Field Crops Aes.. 24: 131-141. The success of intensive, continuous cropping of newly cleared land in the humid tropics is highly dependent upon the method ot land cleanng and subsequent soil management. The objective of this study was to evaluate the effect of different lind clearing regimes, including initial tillage after clear­ ing and subsequent soil management, on crop pcrform.nce on an Ultisol in the Amazon Basin of Peru. The study was conducted on a Yurinaguas soil (iqne-loamy, siliceous, isohyperthermic Typic Paleu­ dult ) covered by a 20-year-old evergreen forest which was cleared at the start of the experiment. Land­ clearing treatments included slash and burn, bulldozing with a straight blade, and bulldozing with a shear blade. Post-clearing tillage methods were chisel-plowing and disking. Post-clearing soil manage­ ment practices (subplots) included (I) flat-planted, no fertilizer or lime added; (2) flat-planted, fertilizer and lime incorporated; and (3) soil bedded at a 1.1 -mspacing and fertilizer and lime ap­ plied. as in subplot 2. The cropping se-quence was upland rice [Or,:asatva L.I-soybean [G/icne inax (.) Mert. ]-corn [Zea mays L. I-rice-corn. !n general, all crops showed a positivc respoise to the post-clearing tillage pi actices of chiseling and disking. The post-clearing soil-management prac!ice combining fertilization, liming, and bedding generally produced the highest yields of rice and corn. The greatest average relative grain-yields, in descending order, were produced by the following man­ agement systems: slash/bum/flat-plant/ferilizer/lime (94% average relatixe grain-yield)> slash/ bum/bedded/fertilizer/lime (90%)> shear-blade/bum/disk/bedded/fertilizcr/lime (88%)> shear­ blade/bum/disk/flat-plant/fertilizer/lime (86%).