ABSTRACT Phosphorus (P) is one of the most limiting elements for plant nutrition in tropical and subtropical soils due to its high binding energy on the surface of iron and aluminum oxides and hydroxides. Flooded rice cultivation occurs in lowlands, influencing redox reactions and P dynamics. This study aimed to evaluate the forms of phosphorus and their lability after soil reoxidation subsequent to a period of flooding for irrigated rice cultivation following four seasons of cultivation with soybean-ryegrass and corn-white […]

ABSTRACT Pork is the most consumed animal protein around the world. The production levels are significant, which results in the generation of large amounts of slaughter waste. Such waste is often disposed of improperly in agricultural areas, causing environmental imbalance by the contamination of soil and water sources with metals and pathogenic organisms. This study evaluates the phytotoxic effects of pig slaughterhouse waste in natura and after stabilization processes on lettuce (Lactuca sativa Linnaeus, 1753), radish (Raphanus sativus Linnaeus, 1753), […]

In the last decades, the use of plant growth-promoting rhizobacteria has become an alternative to improve crop production. Rhizobium leguminosarum biovar trifolii is one of the most promising rhizobacteria and is even used with non-legume plants. This study investigated in vitro the occurrence of plant growth-promoting characteristics in several indigenous R. leguminosarum biovar trifolii isolated from soils in the State of Rio Grande do Sul, Brazil. Isolates were obtained at 11 locations and evaluated for indoleacetic acid and siderophore production […]

In this study available cooper (Cu) content in different sources of this micronutrient was determined using several extractants. The cooper sources were: coppper oxide p.a. + copper powder p.a., copper oxide 40 Ind., CuSO4.5H2O p.a., chalcopyrite ore, copper powder p.a. and copper oxide p.a., and they were used in the following extraction procedures: total Cu content and soluble Cu contents in water, citric acid at 20 g L-1, neutral ammonium citrate (1 + 9) and DTPA at 0.005 mol L-1. […]

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 […]

Methods to quantify available silicon (Si) in fertilizers and slags are not yet sufficiently trustworthy. In this study, Si extracted from several sources was analyzed, using the extractors: Na2CO3 + NH4NO3 in varying concentration, time of agitation and of reaction; water; HCl 0,5 mol dm-3; 50 g dm-3 of Na2CO3; 50 g dm-3 of citric acid; 0,5 mol dm-3 of acetic acid; acid cation exchange resin (Amberlite IRC-50, pK 6.1); and the leaching column method. A greenhouse experiment, where 125 kg ha-1 of total Si from 12 different sources was applied […]

To evaluate residual effects of potassium fertilization throught ryegrass on subsequent rice, under no-tillage system, a field experiment was performed from May 1996 to April 1997 in the Agricultural Center (Centro Agropecuário) of Palma/UFPel, in the county of Capão do Leão, Rio Grande do Sul State, Brazil. The examined soil was a Planossolo (Albaqualf) belonging to the Pelotas mapping unit. Treatments consisted of three K levels applied on the ryegrass (0, 0.5 and 1 time the recommended dose of 70 […]

Zinc solubility in fertilizers (zinc sulfate, zinc oxide, metallic zinc and four FTE) was determined using water, 20 g L-1 citric acid, neutral ammonium citrate (1 + 9) and DTPA as extractant solutions, and the correlation with the availability of this micronutrient for rice and corn plants established. Zinc was most accessible for the plants in sulfate form, followed by oxide, while FTE presented the lowest availability. Neutral ammonium citrate (1 + 9), at a ratio of 1:100 and after […]

In addition to improving chemical attributes of the soil, such as pH, exchangeable Ca and available Si, calcium silicate fertilization in soils with low soluble silicon (Si) can also affect rice yield due to a greater resistance to lodging and increased photosynthetic area. The objective of this study was to evaluate Si availability in soils from the Brazilian savannas (Cerrado). The experiment was carried out in a greenhouse using upland rice. The treatments consisted of 5 Si rates (0, 120, […]

The present study was carried out in 1995 to investigate why plants cultivated in a Red-Yellow Podzolic in the State of Acre, in the Brazilian Amazon, presenting high amounts of exchangeable aluminum, have not shown symptoms of toxicity to this element or yield reduction. The exchangeable Al3+ in the B horizon is higher than 14 cmolc dm-3. Samples of the A and B horizons were incubated with increasing rates of lime and subjected to determination of pH in H2O, pH […]