Given the importance of cohesive soils derived from sediments of the Barreiras Formation, and the extensive area occupied by them in northeastern Brazil, the objective of this study was to identify and characterize the occurrence of cohesive soils in Coastal Plains of Ceara State. Three soil profiles were studied: two cohesive Argisols and one non-cohesive Argisol. Their morphological characteristics and physical, chemical, and mineralogical properties were assessed to confirm the presence of cohesive horizons. The results validated the hypothesis of […]

The effects of pH changes and sewage sludge application on the distribution of Cu, Mn, Ni, Pb, and Zn among exchangeable, organic, amorphous Fe and Al oxides, crystalline Fe and Al oxides, and residual fractions of two soils (and Eutrustox and a Ultipsamment) were studied in a greenhouse experiment carried out at the FCAV-UNESP, in Jaboticabal (SP), Brazil. The heavy metal contents in these fractions were related to those extracted with DTPA, HCl 0.1 mol L-1, Mehlich-1, and Mehlich-3 extractants […]

Soil management alters the physical soil properties and changes the soil air, water, and solute dynamics. Physical soil properties as affected by conservationist soil management systems were studied in a sandy loam Typic Hapludalf. The treatments were established on a soil that has been under no-tillage for 10 years, and consisted of: no-tillage soybeans, chisel tillage soybeans, reduced tillage Crotalaria, and bare soil without tillage. The evaluated soil properties were soil penetration resistance, bulk density, porosity, pore size distribution, saturated […]

Root growth is affected by mechanical soil resistance and affects the crop yield potential. This study evaluated the soil penetration resistance on a clayey Oxisol under distinct no-tillage cropping systems. The experiment was carried out at the technological field of Cotrijui in southern Brazil. The soil was a Haplorthox with a clay content of 0.68 kg kg-1 and it has been under four no-tillage cropping systems: succession soybean/wheat; corn/black oat/corn + velvet bean/wheat/soybean/wheat; velvet bean/wheat/soybean/ wheat/soybean/black oat; and crotalaria/wheat/soybean/black oat/corn/wheat. […]

The application of sewage sludge into agricultural soils, as organic fertilizer or soil conditioner, is becoming an increasingly more attractive alternative. It is occurring because of the high costs and environmental impacts caused by other sludge disposal methods, besides the presence of plant nutrients and organic matter in the sludge and the need to reduce costs in agriculture. However, sewage sludge can contain heavy metals, pathogenic microorganisms, and toxic organic compounds. In order to study the impact of sewage sludge […]

Inadequate soil management systems can lead to water erosion, nutrient losses and superficial water pollution, accelerating environmental degradation. The P and K losses caused by water erosion were evaluated from November 1999 to October 2001 in an Inceptisol with 0.102 m m-1 slope, in Lages, Santa Catarina State, Brazil, under natural rainfall conditions. The evaluated soil management systems were: no-tillage for six years (NT6), no-tillage for nine years (NT9), chiseling plus one disking for nine years (C + D9), and […]

Late season potassium (K) deficiency has been observed quite frequently for cotton crops in the Brazilian cerrado region. One possible reason for such a problem could be the low water availability at this period of the season. Thus, an experiment was conducted in order to quantify the relative contribution of mass flow and diffusion in supplying K to cotton roots, as affected by soil water and K availability. The arable layer of a typic Red Latosol (Haplortox), with 630 mg […]

A field trial was carried out to evaluate the effects of nitrogen and potassium top dressing on upland rice. The treatments consisted of a 5 x 3 factorial design (five nitrogen doses – 0, 25, 50, 75, and 100 kg ha– and three potassium doses – 0, 25 and 50 kg ha-1), arranged in a complete randomized design, with three replicates. The results showed that several yield characteristics were positively influenced by nitrogen and potassium fertilization. The best combination of […]

Iron deficiency in coffee plants cultivated in ferric Latosols may be induced by conditions that affect the transport of this nutrient in soils, such as P concentration, high pH values and low soil moisture content. The iron diffusive flux (FeF) in soils was evaluated as a function of P rates and levels of acidity and moisture. Surface soil samples of a clayey dystroferric Red Latosol and a loamy-sand dystroferric Yellow Red Latosol were supplied with 20 mg dm-3 Fe as […]

The objective of this study was to evaluate alterations in the physical soil quality of a Dystroferric Red Latosol (Typic Haplorthox) caused by chiseling, after thirteen years of no-tillage. The experiment consisted of two management systems: soil chiseling down to a 0.30 m depth (NTC) and no-tillage (NT). Undisturbed soil samples were collected at depths of 0-0.15 m and 0.15-0.30 m, and the soil water retention curve, the soil resistance to penetration curve, the soil bulk density, and the “Least […]