João Kaminski

Biodisponibilidade de formas de fósforo acumuladas em solo sob sistema plantio direto

The addition of fertilizers to the soil increases P contents in many forms of different bond energies with soil colloids. This has been observed in the soil surface layer under no tillage system, however there is little information about the availability of these P forms to plants. The study aimed to evaluate the bioavailability of P forms of a soil under no tillage with P applications. Samples were collected (0-10 cm) in a Rhodic Hapludox that had been fertilized with 0, 180, 360, 540, and 720 kg ha-1 of P2O5 over six years of cultivation prior to this study. The samples were dried, ground, filled in 2 kg pots and subjected to 15 successive crops without replacement of absorbed P. After every three successive crops, soil samples were collected for analysis. Phosphorus fractionation was analyzed by Hedleys method. Results showed that inorganic P extracted by NaHCO3 0.5 mol L-1 has a buffering capacity similar to P available by anion exchange resin, and can be considered labile P as well. In the long term, all soil P forms act in the soil solution buffer. In fertilized soils, the inorganic and organic P forms act in a similar way buffering the absorbed P by plants. In soils with little or no fertilization, the organic forms are the main P source of plants.

ALTERAÇÕES DE ATRIBUTOS DO SOLO PELA CALAGEM SUPERFICIAL E INCORPORADA A PARTIR DE PASTAGEM NATURAL

Superficial liming is an alternative way to correct soil acidity in no till system. The objective of this study was to evaluate the effects of superficial and incorporated liming on native pasture. The experiment was carried out at the experimental field of the Soil Science Department, at the Universidade Federal de Santa Maria (Brazil), on a Plinthaquult medium texture and with high potential acidity under native pasture. Lime rates of 0.0, 2.0, 8.5 and 17.0 Mg ha-1 were used. On half of the plots lime was mixed with the topsoil by disk plow and left on the surface on the other half of the plot. The experimental design was arranged in completely randomized blocks with four replications. After 6, 18, 36, and 48 months, soil was sampled at four depths, 0.0-2.5, 2.5-5.0, 5.0-10.0 and 10.0-15.0 cm and the attributes related to soil acidity evaluated. The surface applied lime was effective in neutralizing soil acidity, at a depth proportional to the rate and time. With 2.0 + 2.0 t ha-1, aluminum saturation reached near zero (0.0-2.5 cm layer) at 36 months; with 8.5 t ha-1, it reached near zero (2.5-5.0 cm) at 36 months; with 17.0 t ha-1 it reached near zero (5.0-10.0 cm) at 48 months.

Fatores que afetam a disponibilidade do fósforo e o manejo da adubação fosfatada em solos sob sistema plantio direto

The basic phenomena of phosphorus dynamics in soil is important to define the rate and application manners of phosphates fertilizers. The forms and availability of phosphorus vary with the soil characteristics and properties. In young soils, the calcium phosphates are the main source to organisms. On the other hand, in highly weathered soils the organic phosphorus cycling assumes great importance in the maintenance of the biological bioavailability, although it is insufficient to economical crop productivity. In tropical and subtropical cultivated soils, the soil phosphorus in solution is controlled by phosphorus adsorbed at functional groups of inorganic colloids. The phosphorus diagnosis is made by soils analysis at different methodologies, each one with their advantages and limitations. The decision on adding phosphate and to the rate define is more dependent on the calibration between the value extracted with the crop yield than the extraction method. The elevation of phosphorus availability can be made in corrective or gradual addition. The corrective fertilization is more efficient, and maybe the only alternative, for phosphorus deficiency correction in deeper soil layers. The correction of phosphorus deficiency in deeper layers after the no-tillage system adoption is difficult. The superficial phosphate application in no-tillage seems not to be a good economical alternative and can become an environmental problem. The research must be intensified focusing among others: (a) phosphorus fractions in soil and crop yield; (b) phosphates fertilizers application in no-tillage system; (c) relation of phosphorus availability with exchangeable aluminum and compacted soil layers in soil deep; (d) monitoring of transferred phosphate from soil to aquatic systems.

Formas de fósforo no solo após sucessivas adições de dejeto líquido de suínos em pastagem natural

The swine industry generates large amounts of pig slurry (PS), which is reused as agricultural fertilizer. However, if applied at excessive rates, pig slurry becomes a severe environmental pollutant. The objective of this study was to evaluate forms of soil phosphorus accumulation after successive swine manure applications. The experiment was installed in 1995, in an area of native pasture. Rates of 0, 20 and 40 m3 ha-1 of PS were applied periodically (at 45 to 60 days intervals) during five years. In 1999, after 28 PS applications totaling 0, 560 and 1.120 m3 ha-1 of PS, soil samples were collected from the layers 0-2.5, 2.5-5.0, 5-10, 10-15, and 15-20 cm. Soil phosphorus in the samples was fractionated using Hedleys fractionation scheme (Hedley et al., 1982). The maximum phosphorus adsorption capacity (MPAC) was determined in soil samples without PS application using the Langmuir model. Results showed that phosphorus added as PS is accumulated essentially in inorganic forms, mainly those extractable by anion exchange resin, NaHCO3 0.5 mol L-1, NaOH 0.1 mol L-1 and HCl 1.0 mol L-1.

Modificações em atributos químicos de solo arenoso sob sistema plantio direto

No-tillage soil management does not permit incorporation of crop residues and requires surface application of fertilizers and corrective agents, thereby affecting nutrient availability and distribution. This study was carried out to evaluate the chemical changes in no-tillage system compared to conventional tillage and native grass field. Samples from a sandy/clay Red-Yellow Podzolic (Typic Hapludalf), taken at 0-5, 5-10, 10-20 and 20-40 cm depth, were used to determine zero point of salt effect (ZPSE), humic substances, permanent charge, soil pH, exchangeable Al, Ca + Mg and H + Al, total and mineral N, available, total and organic P and available, exchangeable and soil solution K. Effective CTC and pH 7.0, aluminum and base saturations and the percentage of organic P were determined. The soil management did not affect the ZPSE. The no-tillage system increased the fulvic and humic acids, nutrient availability, negative charges, and soil acidity.

APLICAÇÃO SUPERFICIAL DE CALCÁRIO NO SISTEMA PLANTIO DIRETO CONSOLIDADO EM SOLO ARENOSO

1 Engenheiro Agrônomo, MSc., Professor Assistente, Departamento de Solos, Centro de Ciências Rurais (CCR), Universidade Federal de Santa Maria (UFSM), 97105–900, Santa Maria, RS. Danilo@creta.ccr.ufsm.br. Autor para correspondência. 2 Engenheiro Agrônomo, MSc., Professor Substituto, Departamento de Solos, CCR, UFSM. 3 Engenheiro Agrônomo, Doutor, Professor Titular aposentado, Departamento de Solos, CCR, UFSM. 4 Engenheiro Agrônomo, Especialista, Professor Titular aposentado, Departamento de Solos, CCR, UFSM. RESUMOSurface liming is an alternative way to correct soil acidity. The objective of this study was to evaluate the effects of surface liming on soil properties and crop yield under no-tillage. The experiment was carried out at Federal University of Santa Maria, Southern Brazil, on a Typic Hapludult, under no-tillage, for five years, with pH 5.0, 13, 140 and 610g kg-1 OM, clay and sand, respectively. The lime rates used were 0, 1.2, 1.8 and 3.6Mg ha-1, applied on the soil surface without incorporation. The crops used were corn (94/95), black oat (95 and 96) and soybean (95/96 and 96/97). Grain yield was evaluated for corn and soybeans; dry matter production was evaluated for black oats. Six, 12, and 18 moths after liming, soil was sampled at four depths, 0-2.5, 2.5-5, 5-10 and 10-15cm to measure some attributes related to soil acidity. Treatments were set up in a complete block design with four replications. Superficial applied lime did not induce crop yield differences, but modified acidity and increased pH, calcium and magnesium contents in the 0-5cm layer.

Depleção do fósforo inorgânico de diferentes frações provocada pela extração sucessiva com resina em diferentes solos e manejos

Available soil phosphorus is maintained by less labile form that, in the long term, can become available to the plants. The aim of this research was to determine the depletion of various inorganic phosphorus fractions after successive extraction with resin. Soil samples were collected in four long-term experiments under no tillage or conventional tillage systems with different crop sequence. The soils (heavy clay Rhodic Hapludox, clay Rhodic Hapludox and clay loam Rhodic Paleudult) were collected from three depths, 0-2.5, 2.5-7.5 and 7.5-17.5 cm. Inorganic phosphorus was fractioned by a modified Hedley technique before and after successive phosphorus extraction by membrane resin. The fraction of phosphorus extracted with 1.0 mol L-1 HCl is not labile. Those extracted with 0.5 mol L-1 NaHCO3 and 0.1 mol L-1 NaOH can be considered labile, regardless the soil type, method of cultivation and crop sequence. In the Oxisols, the inorganic phosphorus fraction extracted by 0.5 mol L-1 NaOH is also labile.

Forms of inorganic phosphorus in soil under different long term soil tillage systems and winter crops

O cultivo de plantas com diferentes habilidades de absorcao e utilizacao de P sob diferentes sistemas de preparo de solo por um longo periodo de tempo pode alterar a ciclagem e a distribuicao das formas de P inorgânico no solo, como resultado de maior ou menor eficiencia de utilizacao do P adicionado via fertilizantes. O objetivo deste trabalho foi avaliar o efeito de longo periodo de cultivo de diferentes especies de inverno sob diferentes sistemas de preparo de solo na distribuicao das formas de P inorgânico do solo. Em 1986, foi estabelecido o experimento com seis tratamentos de inverno (tremoco-azul, ervilhaca-peluda, aveia-preta, nabo forrageiro, trigo e pousio) implantados num Latossolo Vermelho aluminoferrico na regiao sudoeste do Parana, sob sistema plantio direto (SPD) e sistema de cultivo convencional (SCC). A adicao de fertilizantes fosfatados na linha de semeadura no SPD promoveu aumento de P inorgânico, nas formas labeis e moderadamente labeis, e o revolvimento do solo no SCC redistribuiu o P aplicado em profundidade, promovendo aumento no teor de P moderadamente labil no solo das camadas subsuperficiais. A aveia-preta e o tremoco-azul foram mais eficientes na ciclagem de P e, quando cultivados sob SPD, aumentaram o teor de P labil no solo das camadas superficiais.

Formas e dessorção de cobre em solos cultivados com videira na Serra Gaúcha do Rio Grande do Sul

As aplicacoes sucessivas de fungicidas cupricos em videiras podem aumentar o teor de cobre total do solo e modificar a sua distribuicao e dessorcao no perfil do solo. O trabalho objetivou determinar as formas de cobre e a sua dessorcao em solos cultivados com videira e submetidos a sucessivas aplicacoes de fungicidas cupricos. Amostras de um solo Neossolo Litolico e Cambissolo Humico foram coletadas em 2006, nas camadas de 0-20 e 20-40 cm, em um vinhedo com 40 anos, em Bento Goncalves (RS). Amostras de um solo Neossolo Litolico foram coletadas nas mesmas profundidades, em area de mata natural proxima do vinhedo, e os resultados de analise foram usados como referencia. Os solos coletados foram conduzidos ao Laboratorio de Quimica e Fertilidade de Solo da Universidade Federal de Santa Maria, onde foram secos, moidos, passados em peneira de malha de 2 mm, e submetidos ao fracionamento quimico do cobre pela metodologia de Tessier et al. (1979) e a cinetica de dessorcao de cobre com EDTA 0,05 mol L-1, em pH 6,0, conforme proposto por Fangueiro et al. (2005). Os resultados mostram que a aplicacao de fungicidas cupricos em videiras aumenta o teor total e das fracoes biodisponiveis de cobre do solo, inclusive na camada de 20-40 cm. A maior parte do cobre dos solos cultivados com a videira encontra-se retido na fracao mineral, e do solo sob mata natural, na materia orgânica principalmente. A maior quantidade do Cu, independentemente dos materiais adsorventes nos solos cultivados com videira, e facilmente dessorvivel e pode ser considerada em equilibrio rapido com o cobre da solucao.

Damage detection under ambient vibration by harmony search algorithm

Highlights? A new approach for vibration-based (SHM) procedures is presented. ? Stochastic system identification with the evolutionary harmony search algorithm. ? Numerical investigation considering noise levels and a series of damage scenarios. ? Experimental study of three cantilever beams under different damage conditions. ? The methodology has shown potential for use in the damage assessment of structures. Damage in structural systems induced by vibrations, alternating load cycles, temperature changes, corrosion, etc., constitute a serious technical problem. Smart methods of control and structural health monitoring (SHM) for large structures are, therefore, highly needed. In certain structural applications, moreover, a lack of access to the damaged area imposes an additional constraint on damage identification procedures. One method that may fulfill those requirements is dynamic nondestructive testing, which consists of monitoring changes in the structures natural frequencies, vibration modes and damping.In this paper, a new approach for vibration-based (SHM) procedures is presented, in an ambient vibration context; this method combines a time domain modal identification technique (SSI) with the evolutionary harmony search algorithm. A series of numerical examples with different damage scenarios and noise levels have been carried out under impact and ambient vibration. Thereafter, an experimental study of three cantilever beams with several different damage scenarios is conducted and the proposed methodology has shown potential for use in the damage diagnosis assessment of the remaining structural life.