The soils used to grow irrigated rice in the State of Santa Catarina have different mineralogical and chemical characteristics from the soils used for calibration studies of the Mehlich-1 extractant, for estimating soil phosphorus availability to plants. Thus, the aim of this study was to evaluate the effectiveness of Mehlich-1, Mehlich-3, Resin, Olsen and EDTA extractants in predicting P availability to flood irrigated rice in soils of State of Santa Catarina. The experiment was carried out in a greenhouse in […]

Incorporation of rice straw into the soil just before flooding for water-seeded rice can immobilize mineral nitrogen (N) and lead to the production of acetic acid harmful to the rice seedlings, which negatively affects grain yield. This study aimed to evaluate the formation of organic acids and variation in pH and to quantify the mineral N concentration in the soil as a function of different times of incorporation of rice straw or of ashes from burning the straw before flooding. […]

The in situ ion exchange resin membrane allows a partial simulation of the behavior of plant roots regarding phosphorus absorption from soil solution. Soil sampling is rendered unnecessary since the technique is used directly in the soil where the plants are grown and may be a promising methodology in the determination of phosphorus availability for crops. To evaluate the technique, a greenhouse experiment was carried out with resin membranes buried in the soil when plants were sown (day zero) and […]

Lowland soils are seasonally flooded for rice cultivation and undergo alternate oxidation and reduction conditions, which modify the soil solid mineral phase and the dynamics of highly reactive elements such as phosphorus. Low-crystallinity forms of iron oxides and hydroxides become predominant with time. They could be the most important components in phosphorus adsorption during dry periods, and could control phosphorus release after flooding. The objective of this study was to evaluate the maximum phosphorus adsorption capacity (MPAC) of some lowland […]

Phosphorus dynamics in waterlogged soils and sediments is environmentally important and seems closely related to redox reactions of iron compounds. In order to verify the effects of liming and phosphorus fertilization on soil Fe and P contents, nine lowland soil samples from Minas Gerais, Brazil, were treated with two lime and six phosphorus rates. After an aerobic incubation period, the soil Fe and P concentrations were determined by ammonium-acetate, Mehlich-1 and ammonium-oxalate extractants. The soils were then waterlogged and the […]

This research was conducted from May to September, 1995, in order to evaluate liming criteria for rice plants on flooded soils of Minas Gerais State, Brazil. The effects of increasing CaCO3 + MgCO3 dosis on dry matter production were evaluated in a greenhouse pot trial. The experimental matrix was a complete factorial with ten lowland soils and five levels of liming. The soil characteristics which significantly affected the lime levels recommended were: titrable acidity at pH 7,0 (H + Al), […]