Suprimento de potássio em função da adubação potássica residual em um Latossolo Vermelho do Cerrado

Em alguns solos com baixos teores de potássio trocável, formas não trocáveis participam do suprimento às plantas. Há evidências de que a disponibilização do K não trocável depende mais da demanda das plantas pelo nutriente do que das propriedades do solo. O objetivo deste trabalho foi avaliar o suprimento e a exaustão de formas de K em um Latossolo Vermelho do Cerrado em decorrência da adubação potássica residual e do cultivo de Brachiaria ruziziensis (Syn. Urochloa ruziziensis). Amostras de solos foram coletadas na camada de 0-20 cm, em parcelas de um experimento de campo em que a soja vinha sendo adubada anualmente, por 10 anos, com 0, 60, 120 e 180 kg ha-1 de K2O. em casa de vegetação, as amostras de solo receberam a aplicação de 0, 150 e 300 mg dm-3 de K e foram cultivadas com B. ruziziensis, com cinco cortes sucessivos. O suprimento de K às plantas dependeu mais do fertilizante recém-adicionado do que do efeito residual de adubações anteriores. O K não trocável foi responsável, ao longo do tempo, pela manutenção dos teores de K trocáveis e, na ausência de adubação potássica, constituiu a principal fonte de K para as plantas de B. ruziziensis. As plantas de B. ruziziensis possuem capacidade de extrair quantidade considerável de K do solo, confirmando sua importância como cultura de cobertura, na ciclagem do nutriente no solo.

Phosphorus and potassium balance in soil under crop rotation and fertilization

The use of crop rotation and manure application can provide sustainability for an agricultural production system by improving soil quality and increasing nutrient use efficiency. This study aimed to evaluate the effect of mineral, organic and mineral+organic fertilization on grain yield and on soil phosphorus and potassium balance, in two crop systems under no-till, with and without rotation of cover crops. The experiment was carried out from 2006 to 2008 on a clayey Rhodic Hapludox in Marechal Candido Rondon, Parana State, Brazil. The cropping sequence in the rotation system involving cover crops was black oat + hairy vetch + forage turnip/corn/pigeon pea/wheat/mucuna + brachiaria + sunn hemp, and in the succession system was wheat/corn/wheat/soybean. Organic and mineral+organic fertilizations consisted of the application of solely manure and manure combined with mineral fertilizer, respectively. Soil P and K balances were calculated after the second year of the experiment, up to a depth of 0.40 m. First year corn yields were higher in the crop succession system accompanied by mineral fertilization. In the second year, wheat and soybean yield did not vary between crop systems and nutrient sources, demonstrating the residual effect of crop rotation and manure use. Crop rotation with cover crops resulted in an increase in soil K levels by promoting the recycling of this nutrient in the soil. In both crop systems, the application of mineral and organic fertilizers - either in isolation or in combination - resulted in a negative soil P and K balance in the short term. This represents a threat to the sustainability of the agricultural production system in the long term, due to the depletion of soil nutrient reserves.

Revegetation and Soil Management Effects on Chemical Properties of a Saprolite Resulting from Deep Soil Removal

During the building of a hydroelectrical power plant at Ilha Solteira in the Parana River (Brazil), materials of a highly weathered soil Oxisol were extracted from a depth between 5 and 8 m for engineering works. This resulted in an abandoned depression area. The topsoil was not salvaged and the open pit was not backfilled, and as result vegetation hardly or not at all recovered. on the residual saprolite materials, an experimental field was established to assess different soil rehabilitation treatments. Field experiments were initiated in 1992. After soil tillage, two different crops and three different liming strategies were compared, giving six combinations. In addition, two uncropped control treatments, tilled and no-tilled, were established so that a total of eight treatments were assessed. The experimental design consisted of four randomized experimental blocks, which included a total of 32 plots with a plot area of 100 m(2). This experiment was used to study the effectiveness of the soil-reclamation treatments after a 9-year period. Soil samples were taken at three different depths (0-10, 10-20, and 20-40 cm), and they were analyzed routinely for pH, organic-matter content, and cation exchange capacity (CEC). Revegetation of the abandoned saprolite material increased soil organic-matter content and cation exchange capacity (CEC), and to some extent small differences between treatments were evidenced. Exchangeable calcium (Ca) and magnesium (Mg) recovered faster than organic-matter content. A significant linear relationship was found between organic-matter content and CEC, suggesting continued addition of organic material will further approach the value of these parameters to those levels corresponding to natural soils under "Cerrado" vegetation.

Efeito residual da escória de siderurgia como corretivo de acidez do solo na soqueira de cana-de-açúcar

A escória de siderurgia, como material corretivo e efeito residual prolongado, pode beneficiar culturas de ciclo longo, a exemplo da cana-de-açúcar, minimizando a queda de produção ao longo do ciclo produtivo. Este trabalho objetivou avaliar diferentes níveis de saturação por bases, utilizando, como corretivo do solo, a escória de siderurgia, comparando-a com calcário calcítico, nas alterações de alguns atributos químicos do solo, bem como na resposta da soqueira da cana-de-açúcar. Para isto, realizou-se um experimento com a variedade SP 80-1842, durante o terceiro e o quarto corte, nos anos agrícolas 2000/01 e 2001/02. Os tratamentos, dispostos em blocos casualizados, em esquema fatorial com quatro repetições, constaram de duas fontes de corretivos, calcário calcítico e escória de siderurgia, e quatro níveis de correção, estimados pelo método da saturação por bases (V %): testemunha (sem correção) e com correção para V % de 50; 75 e 100, tendo sido tais corretivos aplicados na época do plantio da cana-de-açúcar. O calcário calcítico e a escória de siderurgia promoveram efeito residual benéfico, após 48 meses da aplicação, na correção da acidez do solo e na elevação do valor da saturação por bases; a maior dose de calcário causou efeito depressivo no perfilhamento, no número de colmos industrializáveis e na produção da cana-de-açúcar, fato não observado com uso da escória de siderurgia; a aplicação da escória de siderurgia e do calcário, em pré-plantio, promoveu efeito residual positivo na produção da soqueira de cana-de-açúcar.

Modelos de minimização de biomassa residual

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Soil remediation using a coupled process: soil washing with surfactant followed by photo-Fenton oxidation

In the present work the use of a coupled process, soil washing and photo-Fenton oxidation, was investigated for remediation of a soil contaminated with p.p'-DDT (DDT) and p.p'-DDE (DDE), and a soil artificially contaminated with diesel. In the soil washing experiments,Triton X-100(TX-100) aqueous solutions were used at different concentrations to obtain wastewaters with different compositions. Removal efficiencies of 66% (DDT). 80% (DDE) and 100% (diesel) were achieved for three sequential washings using a TX-100 solution strength equivalent to 12 times the effective critical micelle concentration of the surfactant (12 CMC(eff)). The wastewater obtained was then treated using a solar photo-Fenton process. After 6 h irradiation, 99, 95 and 100% degradation efficiencies were achieved for DDT, DDE and diesel, respectively. In all experiments, the concentration of dissolved organic carbon decreased by at least 95%, indicating that residual concentration of contaminants and/or TX-100 in the wastewater was very low. The co-extraction of metals was also evaluated. Among the metals analyzed (Pb, Cr, Ni, Cu. Cd, Mn and Co), only Cr and Mn were detected in the wastewater at concentrations above the maximum value permitted by current Brazilian legislation. The effective removal of contaminants from soil by the TX-100 washing process, together with the high degradation efficiency of the solar photo-Fenton process, suggests that this procedure could be a useful option for soil remediation. (C) 2009 Elsevier B.V. All rights reserved.

Efeito residual de flumioxazin sobre a emergência de plantas daninhas em solos de texturas distintas

Com o objetivo de avaliar o efeito residual de flumioxazin sobre a emergência de plantas daninhas em solos de texturas distintas, foi realizado um experimento em casa de vegetação. Os tratamentos foram constituídos pela combinação de quatro épocas de aplicação: 14, 10, 7 e 0 dias antes da semeadura das espécies de plantas daninhas, com duas doses de flumioxazin (25 e 40 g ha-1) e uma testemunha sem aplicação para cada planta daninha em solos de texturas distintas. O efeito residual do herbicida flumioxazin foi avaliado por meio da contagem do número de plantas emersas de cada espécie aos 35 dias depois da semeadura (DDS). O controle do fluxo inicial de emergência de plantas daninhas variou em função do tipo de solo, do período de tempo entre a aplicação e a semeadura das espécies e também da dose. A. tenella, D. horizontalis, D. insularis, D. tortuosum, E. heterophylla, N. physaloides e S. latifolia foram as espécies mais sensíveis à aplicação de flumioxazin (25 e 40 g ha-1).

Efeito residual de herbicidas aplicados em pré-emergência em diferentes solos

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Sugarcane grown in an oxisol amended with sewage sludge and vinasse: nitrogen contents in soil and plant

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Residual and annual potassic fertilization for soybeans

There is a lack of long-term research on potassium fertilization for soybean in the tropical and subtropical soils of Brazil and the residual effect of the fertilizer has generally not been considered. An experiment was conducted in plots that had been fertilized with 0, 40, 80, 160 and 240 kg ha(-1) of K2O for 3 years on a Dark Red Latosol, loamy sand (Acrortox). The effects of annual or residual fertilization with those rates of K were studied for three additional years. Potassium was supplied as potassium chloride or potassium sulphate. Soil and leaf samples were taken annually. There was a residual effect of the nutrient, which provided for high yields up to the 3rd year with the highest rate of K. In order to maintain the K contents of the soil in the medium range and obtain at least 90% of the maximum grain yield, an annual application of 80 kg ha(-1) of K2O was necessary, irrespectively of the source. The highest soybean yields were always associated with K levels above 15 mg kg(-1) in the leaves and 1.2 mmol(c) dm(-3) in the soil.

Experimental investigation of soil and groundwater impacts caused by vinasse disposal

The problems caused by the residual effluents of wine distilleries for alcohol production are well known. The effluent effects in soil and groundwater are being researched in an area with sugar cane culture which receives, yearly, vinasse by dispersion. Samples are being collected from the soil, the groundwater and the existing creeks in the area. Four sub-areas are being monitored separately with a vinasse application of 300 m 3/ha year. Experimentation periods in each area have been 0, 5, 10 and 15 years. In the unsaturated zone, samples are being collected at depths of 25, 75 and 150 cm. The chemical analyses include macro and micro nutrients, organic matter and pH. Physical analyses give the soil water retention, hydraulic conductivity and soil particle distribution. These measurements permit the evaluation of nitrogen absorption and fertility changes of the soil. A tendency for the maintenance of soil fertility can be observed but with an elevation of nitrate concentration in groundwater.

Heavy metals availability and fractions in soil amended with biosolid composts

The heavy metals when linked to organic matter have a behavior in the soil that is still little known. This study aimed to evaluate the effect of sewage-sludge-based composts when incorporated in the soil, in relation to heavy metals availability. Five composts were incorporated using sugar-cane bagasse, sewage sludge and cattle manure in the respective proportions: 75-0-25, 75-12.5-12.5, 75-25-0, 50-50-0 and 0-100-0 (composts with 0, 12.5, 25, 50 and 100% sewage sludge). The experiment consisted of 6 treatments (5 composts and a control with mineral fertilization) in randomized blocks with a split-plot design. The control and the treatment of 0% sewage sludge received inorganic nitrogen (N). All the treatments received the same amount of N (8.33 g) K (5.80 g) and K (8.11 g) per pot. Tomato plants were cultivated in 24.0 L pots in a greenhouse in Jaboticabal, SP, Brazil. The concentrations of heavy metals were determined in the soil samples at day 0 after compost incorporation. The higher the sewage sludge doses, the higher heavy metal contents in the soil. Among extractants, Melhlich-1 extracted the highest amount of heavy metals, while DTPA extracted the lowest one. The residual fraction presented the highest heavy metal content, followed by Fe oxides crystalline and amorphous to Cu, Cr and Mn, and Mn oxides, and Fe amorphous to Zn, indicating strong associations to oxides and clays. There were significant positive correlations between Mn contents in the plant and Mn linked to Fe oxide amorphous and crystalline.

Carbono orgânico e carbono residual do solo em sistema de plantio direto, submetido a diferentes manejos

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Zinc and lead content and availability in Brazilian soil contaminated with residue of a secondary smelting lead recycling plant

The sequential extraction procedure of Zinc and lead performed in a Brazilian soil showed that it presents high pollution potential once over 90% of total lead is present in fractions where the metals can be easily mobilized. The fraction contents are as follow: F1 = 174 and 15 mg kg-1; F2 = 3155 and 9.7 mg kg -1; F3 = 99 and 1.6 mg kg -1; Residual fraction = 38 and 5.5 mg kg -1 for lead and zinc, respectively. The comparison with non contaminated soil only Pb 2+ concentration is above its intervention reference concentration, 900 mg kg -1.

Efeito residual de fontes de fósforo nos atributos químicos do solo, nutrição e produtividade de biomassa da cana-de-açúcar

In tropical regions, the residual effect of phosphate fertilizer source is of crucial importance. This study aimed to evaluate the effects of application of P sources in chemical properties of soil, nutrition and productivity of sugarcane plant and during the first and second ratoon. The sources of P applied in furrows at planting were, triple superphosphate, Arad phosphate, bone meal (100 kg ha-1 P2O5 total) and a control without P, the varieties of sugarcane studied were IAC86-2480 and SP79-1011. A randomized block design in a 4 × 2 factorial was used, with four replications. The study was conducted in the municipality of Alta Floresta-MT, Brazil, in Typic Hapludox. After each cutting, in soil P content, pH and Ca were evaluated. In the plant, the production of green and dry matter of shoots, the concentration of P in the biomass harvested, the export of P and agronomic efficiency of the sources of P were determined. The bone meal had a higher agronomic efficiency resulted in greater accumulation and export of P by crop, higher content of available Ca and P and increase soil pH. The Arad reactive phosphate increased its agronomic efficiency between crop cycles.