Effect of Land Clearing Method on Chemical Properties of an Ultisol In the Amazon

Abstract

This study quantified soil chemical properties as affected by land clearing method and subsequent soil management. It was conducted on a Yurimaguas soil (fine‐loamy, siliceous, isohyperthermic Typic Paleudults) covered by a 20‐yr‐old evergreen forest in the Amazon Basin of Peru. The experimental design, a split plot replicated three times, included six main plot treatments: (i) slash and burn clearing; (ii) bulldozer clearing with a straight blade; (iii) straight blade clearing followed by chisel plowing 25 cm deep; (iv) bulldozer clearing with shear blade, vegetation burned, followed by disking 30 cm deep; (v) shear blade clearing and rototilling with a 10‐KW tractor; and (vi) shear blade clearing, 30‐cm‐deep disking, followed by rototilling. Three post clearing soil management practices (subplots) were: (1) flat planted with no fertilizer or lime; (2) flat planted with fertilizer and lime applications incorporated, based on soil test recommendations; and (3) soil bedded at 1.1‐m spacings, and fertilizer and lime applied as in Subplot 2. Five successive crops, rice (Oryza sativa L.)‐soybean [Glycine max (L.) Merr.]‐corn (Zea mays L.)‐rice‐corn were grown from July 1980 to July 1982. Soil samples collected before or just after harvest of the first, second, and third crops were analyzed for chemical properties. Burning dried vegetation resulted in higher concentrations of Ca, Mg, P, and K in the 0‐ to 45‐cm soil layer. No significant differences due to main treatments were found for the other chemical properties. The pH of the surface soil increased from 4.0 to 5.2 for all limed subplots. Percent aluminum saturation decreased from 82 to 7%, and P, Ca, Mg, and effective cation capacity increased. The decrease in topsoil organic carbon at 14 wk for all mechanically cleared treatments was probably due to increased oxidation rates due to tillage and higher soil temperatures. Concentrations of Cu, Fe, and Mn in the soil were unaffected by treatment.

Monitoring land degradation in the semiarid tropics using an inferential approach: the Kabomo basin case study, Nigeria

“…These results con®rm the conclusions from a number of studies in dierent environments that degradation of soil properties occurs following replacement of natural forests with land-use practices (Cunningham, 1963;Seubert, et al, 1977;Adepetu, et al, 1979;Aina, 1979;Agboola, 1981;Kang and Juo, 1986;Alegre, et al, 1988;Ghuman and Lal, 1991;Kang, 1993;Hulugalle, et al, 1994;Lal, 1996). The rate of decline of the aected soil properties appears to be generally higher under arable farming than under livestock ranching or legume grass farming (Table II) despite the fact that the chemical fertilizer NPK is used annually in treating the soils of the arable plot.…”

Nutrient Loss and Redistribution After Forest Clearing on a Highly Weathered Soil in Amazonia

“…7). In ecosystems investigated soon after disturbance, particularly burning, elevated concentrations of available P have been observed (Alegre et al 1988). In our study, 27 yr after disturbance, vegetation regrowth or P loss has led to a depletion of ϳ1 kg/ha of Melich-III-extractable P in the upper 10 cm of soil compared to the mature forest.…”

Soil fertility status under shifting cultivation in East Kalimantan with special reference to mineralization patterns of labile organic matter

“…Burning has been intensively studied and is thought to supply bases and phosphorus via ash input (Alegre et al 1988;Ewel et al 1981;Giardina et al 2000;Leonard et al 1998;Nye and Greenland 1960;Raison et al 1985;Tanaka et al 1997). In addition, N supply is increased by enhanced mineralization after burning (Knoepp and Swank 1993;Marion et al 1991;Nye and Greenland 1960;Sakamoto et al 1991;Tanaka et al 2001).…”