Properties and Management of Soils in the Tropics

Abstract

Soil physical properties are those responsible for the transport of water, solutes, air and heat in the soil. The main physical soil properties are depth, temperature, texture, structure, bulk density and water-holding capacity. The main processes involved are infiltration, tillage, compaction, percolation, leaching, runoff and erosion (Fig. 6.1). The critical take-home message of the first edition was that there is a difference in water tensions in clayey Oxisols and other Ci soils (Chapter 5) as compared to soils with high-activity clays. This difference is due to strong granular structure of Fig. 6.1 Runoff and erosion during an intense rainstorm on an Andisol (Ustand) near Arusha, Tanzania. Photo courtesy of Markus Walsh

Adubação nitrogenada na cultura do milho

“…Como não foram observadas variações significativas nos teores de MO entre as parcelas que receberam monocultura e rotação, que pudessem refletir desuniformidade na área experimental, pode ter ocorrido efeito na mineralização do N por causa do preparo do solo, com menor intensidade de sua mobilização. O preparo de solo associado ao sistema de irrigação tende a proporcionar umidade suficiente para a decomposição da matéria orgânica (Sanchez, 1976). Autores têm relatado que sistemas de manejo conservacionistas criam um ambiente no solo diferente do verificado no sistema convencional, com acúmulo superficial de matéria orgânica e de fertilizantes (Schulte & Bundy, 1985).…”

Peach palm growth and heart-of-palm yield responses to liming

“…It worth noting that especially for plant height (a trait highly correlated to the harvest time and heart-of-palm yield), the highest tested liming rate (14.6 Mg ha -1 ) resulted in smaller values than the control (Figure 1b), suggesting overliming effects. As suggested by Sanchez (1976) and Quaggio (2000), the major consequences of overliming are yield reduction, soil structure deterioration, and reduced availability of phosphorus, boron, zinc, and manganese. Yield response to lime, as evaluated by percentage of harvestable plants (Figure 2a), heart-of-palm (Figure 2b), and residue (basal and apical) yield at the first harvest (Figure 2c), was significant (P < 0.01) and similar to plant diameter and height (Figures 1a and 1b).…”

“…Although significant responses to lime application have been frequently observed on acid peat soils, especially for those two palm species, it is not clear whether this response was due to a direct effect of Ca and Mg supply and reduction in toxic Al, or to an indirect effect of making N, P and micronutrients more readily available. Acid soil infertility is frequently due to three major factors: aluminum toxicity, calcium or magnesium deficiency, and manganese toxicity (Sanchez, 1976). Nevertheless, palms are known to tolerate high concentration of exchangeable Al and they usually do not respond to P supply (Ollagnier et al, 1970, Romney, 1987Tampubolon et al, 1990), due to their high mycorrhizal colonization (Sieverding, 1991;Marschner, 1996;Sudo et al, 1996).…”

Germinação de sementes e inoculação de mudas de Macacaúba (Platymiscium Trinitatis Benth. - Leguminosae Papilionoideae) com rizóbios em latossolo amarelo

“…repicadas para solo latossolo amarelo textura argilosa, coletado após a queima da vegetação. (Sanchez, 1976), e a presença de Ν disponível, mineralizado da matéria orgânica por reações de amonificação e nitrificação (Barruenco et al, 1985), tem forte efeito inibidor para o estabelecimento e desenvolvimento de nódulos em leguminosas (Hallsworth, 1958;Robson, 1978 …”