Spesiasi Aluminium Terlarut dan Sifat Kimia Ultisol yang Diameliorasi dengan Dolomit dan Lignit-Teraktivasi

Phytotoxicity of soil aluminum (Al), both directly to the plant growth as well as indirectly through the increase of soil potential acidity, is closely related to the occurrence of various soil soluble-Al species. Amongst them, Al3+ and monomeric-Al species are the primary causes of Al phytotoxicity in soils with high Al content. This study was aimed to evaluate the effects of soil amelioration with dolomite and base-activated lignite (BAL) on changes in soluble-Al species and other soil chemical properties, and vegetative growth of soybean (Glycine max Merr) on Ultisol of Jasinga (Al-dd 16,03 cmol(+)/kg). A green house experiment was conducted by applying a Completely Randomized Design with dolomite and BAL amelioration as the treatments, each with three levels of repectively 0, 1, 1,5 x exchangeable-Al and 0, 2,5, 5 tons BAL ha-1, and three replications. The ameliorants were incubated at field capacity of soil moisture content for one week before planting soybean for one month. Soil soluble-Al speciation was carried out using colorimetric aluminon method to determine concentrations of total soluble-Al, monomeric-Al, and polymeric-Al species. Monomeric-Al were further speciated into inorganic monomeric-Al and organic monomeric-Al species. The results revealed that only dolomite amelioration that significantly increased soil pH-H2O, pH-KCl, Ca- dd, Na-dd, and decreased exchangeable-Al concentration, except for those of all soluble-Al species that only showed a decreasing trend. Soil exchangeable-Al that was negatively and significantly correlated with soybean measure parameters were plant height, root length, total roots and shoots wet and dry weights, as well as Ca concentration. These results indicated that soil Al phytotoxicity evaluation could be relied on the result of routine analysis on soil exchangeable-Al concentration. Keywords: exchangeable-Al, inorganic monomeric-Al, organic monomeric-Al, polymeric-Al

Physical, Chemical, Morphological and Mineralogical Characterization Surface and Subsurface in Hydromorphic and Non-hydromorphic Soil of the Central Amazon

Amazonian soils have some physical, chemical and mineralogical differences, understanding the differences is important to understand the behavior of nutrients in the soil, especially phosphorus. The study was carried out in two types of soils: a Hydromorphic soil profile and a Non-hydromorphic soil profile in the Central Amazon region of Brazil, located in the metropolitan area of Manaus. Five depths were sampled: 0.00-0.05; 0.05-0.1; 0.1-0.2; 0.2-0.4; and 0.4-0.6 m. Physical, chemical, mineralogical and morphological attributes of both soils were studied. With the exception of clay, the levels of sand and silt remained stable in depth. The levels of organic matter gradually decrease in depth. The pH in water and in KCl, ∆pH, point of zero load, were similar between the surface and subsurface soils. Al3+, H++Al3+, CECt, CECT and clay activity were similar in Non-hydromorphic soil and increase in surface (< 0.2 m) and stabilize in subsurface (> 0.2 m). In both soils, the bases are reduced in subsurface (> 0.2 m). Aluminum and iron oxalate reduce with greater expressiveness in Non-hydromorphic soil. Aluminum and dithionite iron exhibit the same behavior. The levels of Goethite (Gt) and Hematite (Hm) are high in depth in the Non-hydromorphic soil and decrease in the Hydromorphic soil. There are sensitive distinctions between soils, due to the imposed edaphoclimatic conditions.

Changes in chemical properties of distrophic Red Latosol as result of swine wastewater application

Swine wastewater (SW) has characteristics that allow its disposal in the soil as a fertilizer. This is an alternative in order not to accumulate this material in the farm as well as it provides savings with mineral fertilizers. The aim of this study was to evaluate the effect of applying swine wastewater on the chemical properties of a distrophic Red Latosol for two seasons. The experiment was carried out under field conditions with treatments defined as T0 = 0 (control), T1 = 150, T2 = 300, T3 = 450, T4 = 600, T5 = 750 m3 ha-1 of SW applied during the crop cycle of elephant grass. SW application contributed to the increase of magnesium and phosphorus and the reduction of soil aluminum in the first season. As for the second season when compared to the first one, there were reductions in K, Ca, and P concentrations. Hence applications of SW did not contribute to the increase in concentration of elements in the soil.