Successive Applications Of Pig Slurry Research Articles

Aggregation Index and Carbon and Nitrogen Contents in Aggregates of Pasture Soils under Successive Applications of Pig Slurry in Southern Brazil

Pig slurry (PS) applications affect soil aggregation and carbon and nitrogen contents in aggregates. The objective of this study was to evaluate changes caused by successive applications of PS and mineral fertilizer on soil aggregation and carbon (C) and nitrogen (N) contents in aggregates of a clayey Typic Hapludox cultivated with Cynodon dactylon cv. Tifton-85 in southern Brazil. The treatments consisted of six annual applications of PS (100, 200, 300, and 400 kg N ha−1) and urea (200 kg N ha−1), and a control with no fertilizer application. Soil samples were collected in March 2019 and evaluated for aggregate stability, through the geometric mean diameter of aggregates (GMD), and GMD sensitivity index (SIGMD), and mass of macro-, meso-, and microaggregates. Total organic carbon and nitrogen contents were determined in macroaggregates and microaggregates. Applications of PS to pasture soils increase dry matter production of Tifton-85 and can increase soil aggregation by increasing the mass of macroaggregates. The highest PS rates decreased aggregate stability, resulting in lower macroaggregate mass, GMD, and SIGMD, and higher microaggregate mass. PS applications to pasture soils can increase C and N contents in macro and microaggregates, and improve soil aggregation when using the rates of 100 or 200 kg N ha−1, mainly in subsurface layers.

Phosphorus forms leached in a sandy Typic Hapludalf soil under no-tillage with successive pig slurry applications

Successive pig slurry (PS) applications can substantially increase phosphorus (P) movement due to leaching, mainly in sandy soils found in areas presenting high rainfall rates. The aim of the current study was to assess the transference of different P forms through leachate in a soil managed under no-tillage system, in a crop rotation system subjected to successive PS applications. The study was carried out from 2005 to 2007; the studied site presents Typic Hapludalf soil and its mean annual rainfall reaches 1,769 mm. The study adopted PS doses 0, 20, 40 and 80 m3 ha-1, which were applied to soil surface before each crop-sowing process. Leachate samples were collected 0.60 m down in the ground at each rainfall event (n = 24) that resulted in solution leaching during the experimental period. Available-P, soluble-P, particulate-P and total-P concentration in the leachate were determined. Successive PS applications increased leachate and P transfers in the leached solution. Phosphorus was transferred via leaching mainly in the particulate form, but soluble-P concentration increase was also observed. The highest P concentrations were observed in the treatment with the highest PS dose, whereas the highest P amounts were transferred in the treatment 40 m3 ha-1 of PS. The total amount of transferred P was very small – 0.2 kg ha-1 year-1 –, but it evidenced the likelihood of groundwater contamination, mainly due to increase in the available-P proportion. In addition, P concentrations in the leachate indicate that high and frequent PS doses should be avoided in sandy soils.

Soil physical indicators of management systems in traditional agricultural areas under manure application

ABSTRACT Studies of the successive application of manure as fertilizer and its combined effect with long-term soil management systems are important to the identification of the interdependence of physical attributes. The aim of this study was to evaluate changes in the physical properties of a Rhodic Kandiudox under management systems employing successive applications of pig slurry and poultry litter, and select physical indicators that distinguish these systems using canonical discriminant analysis (CDA). The systems consisting of treatments including land use, management and the application time of organic fertilizers are described as follows: silage maize under no-tillage (NT-M7 years); silage maize under conventional tillage (CT-M20 years); annual pasture with chisel plowing (CP-P3 years); annual pasture with chisel plowing (CP-P15 years); perennial pasture without tillage (NT-PP20 years); and no-tillage yerba mate (NT-YM20 years) and were compared with native forest (NF) and native pasture (NP). Soil samples were collected from the layers at the following depths: 0.0-0.05, 0.05-0.10, and 0.10-0.20 m, and were analyzed for bulk density, porosity, aggregation, flocculation, penetration resistance, water availability and total clay content. Canonical discriminant analysis was an important tool in the study of physical indicators of soil quality. Organic fertilization, along with soil management, influences soil structure and its porosity. Total porosity was the most important physical property in the distinction of areas with management systems and application times of manure for the 0.0-0.05 and 0.10-0.20 m layers. Soil aeration and micropores differentiated areas in the 0.05-0.10 m layer. Animal trampling and machinery traffic were the main factors inducing compaction of this clayey soil.

English

Soil contamination with zinc occurs in mining and agricultural areas through successive applications of pig slurry. Essential to the selection and adaptation of plants to contaminated soil, is the study of species showing not only tolerance but also bioaccumulation or bioconcentration of zinc associated with amelioration. In this context, this study aimed to evaluate the influence of peat addition on the tolerance, bioconcentration and bioaccumulation of Zn in Eucalyptus grandis seedlings. A completely randomized experimental design was used, in a factorial arrangement (2 x 6), with and without the addition of peat (200 mL L-1 soil) and six doses of Zn (zero, 200, 400, 600, 800 and 1000 mg kg-1) with 15 replications, conducted for 120 days. The height, stem diameter, root and shoot dry weight, concentration and Zn content in the root system and aerial parts, indices of tolerance and translocation, and bioaccumulation factors and bioconcentration were evaluated. The addition of 200 mL L-1 of peat provided increased tolerance and a stimulating effect on morphological parameters of E. grandis seedlings. This species, however, did not concentrate zinc to the extent that it could be considered a bioaccumulating plant. Key words: Contaminated soil, phytoremediation, zinc contamination, amelioration.

Nitrate and ammonium content in percolated water after successive application of swine manure in soil cultivated with soybean

The objective of this study was to determine the amount of percolated water per day and the levels of ammonium and nitrate leachate during soybean cultivation, based on precipitation and fertilization (mineral fertilization, 25 and 100 m3 ha-1 of liquid swine manure) in order to provide results that improve the handling of liquid swine manure, reducing costs and avoiding possible environmental impacts. After 14 years of successive applications of pig slurry, nitrate concentrations determined in water were lower than the maximum values established by the environmental guidelines (Conama 396), indicating that the risk of soil and water contamination is low.

Physiological Changes in Maize Grown in Soil with Copper and Zinc Accumulation Resulting from the Addition of Pig Slurry and Deep Litter over 10 Years

The aim of the present study was to evaluate if increased Cu and Zn concentrations in soils, as a consequence of distribution at the field level for 10 consecutive years of pig slurry (PS) and pig deep litter (DL), would cause toxicity to maize plants affecting, in turn, the biomass production and grain yield. With this aim, maize was grown in two cycles in undisturbed samples from soil that had been fertilized with annual applications of 90 or 180 kg N ha−1, either as PS or DL, in a field experiment carried out for 10 years in southern Brazil. The PS180 and DL180 treatments resulted in Cu and Zn accumulation in soil, and PS180 resulted in Zn accumulation in the tissue of maize plants. The increased availability of Cu and Zn was associated to slight changes in stomatal density, chlorophyll content, and catalase and ascorbate peroxidase activities. Nevertheless, soluble carbohydrate and protein contents and plant dry matter accumulation were not significantly affected by exposure of plants to those high levels of either metal. The results here presented indicate that, although successive applications of PS and DL resulted in a really considerable increase of Cu and Zn in the soils, they do not cause toxic effects in maize plants as to impair their ability to produce biomass and grain.

Changes in physical properties and organic carbon of a Kandiudox fertilized with manure

ABSTRACT: Successive applications of pig slurry and poultry manure can improve the soil structure, according to the land use conditions and amounts applied. This study evaluated the effect of manure fertilization on the physical properties and organic carbon of a Rhodic Kandiudox. Treatments included land use and management and time of pig slurry and poultry litter application, namely: native forest (NF); yerba mate after 20 years of animal waste application (YM20); pasture after 15 years of application (P15); grassland after 20 years of manuring (PP20); grassland after 3 years of manuring (P3); pasture without application (P0), maize after 20 years of application (M20); and maize after 7 years of application (M7). Soil samples were collected in the 0-5, 5-10 and 10-20cm layers, in which density, porosity, aggregate stability, flocculation, penetration resistance, available water, and total clay content, total and particulate organic carbon, and C:N ratio were analyzed. The total organic carbon is sensitive to management and was not related to waste application, except in the 10-20cm layer of ryegrass pasture after three years of manuring. Reponses to waste application and land use and management systems were observed in the variables soil density and penetration resistance.

Soil solution concentrations and chemical species of copper and zinc in a soil with a history of pig slurry application and plant cultivation

Successive pig slurry applications may increase soil copper (Cu) and zinc (Zn) concentrations and change the proportions of free chemical species in solution when combined with plant cultivation. The aim of this study was to assess the soluble, available, and total Cu and Zn concentrations and the distribution of their chemical species in the solution in a Hapludalf soil with a history of pig slurry application and plant cultivation. The study was conducted in undisturbed soil columns that originated from an 8-year-long experiment conducted at the experimental unit of the Federal University of Santa Maria in Santa Maria, southern Brazil. The soil was a Typic Hapludalf soil fertilized with pig slurry at rates of 0, 20, 40, and 80m3ha−1. The soil was collected from depth intervals of 0–0.05, 0.05–0.1, 0.1–0.2, 0.2–0.3, 0.3–0.4, and 0.4–0.6m before and after cultivation with black oat and maize in a greenhouse to assess the total and available Cu and Zn concentrations and to extract the solution. The soil solution concentrations of the main cations, anions, and dissolved organic carbon (DOC) and pH were assessed. The distribution of Cu and Zn chemical species was assessed using the Visual Minteq software. The history of 21 pig slurry applications increased the concentration of Cu and Zn in surface soil intervals, but the concentration of Cu also increased in the soil solution at depth. The phytotoxicity caused by Cu and Zn may not occur even after several years of pig slurry application because the plants provide soil conditions in which chemical species complexed with dissolved organic carbon predominate and Cu and Zn in free forms are present only in small amounts.

Copper and zinc accumulation and fractionation in a clayey Hapludox soil subject to long-term pig slurry application

Pig slurry (PS) recycling as fertilizer is commonly practiced as an option for minimizing livestock waste. Successive PS applications on the soil can lead to crop toxicity and environmental risk. Despite extensive investigation of macronutrient behavior, the fate of trace metals remains uncertain and only a few long-term field studies have been reported to date. This study was designed to assess the impact of 11-year continuous PS spreading on Cu and Zn accumulation and fractionation in a Brazilian clayey Hapludox soil. Three different PS application rates – 50, 100 and 200m3ha−1year−1 – were monitored at six soil depths in comparison to a non-amended control soil. The modified Geological Survey of Canada sequential extraction protocol was applied. A statistically significant increase in Cu and Zn total concentration (assessed by the sum of fractions) was noted only within the 0–5cm soil layer for the 50 and 100m3ha−1year−1 (PS50 and PS100) treatments, and up to 10–15cm for the 200m3ha−1year−1 (PS200) treatment. The mass balance, determined for the 22 PS amendments over the period, confirmed the overall exogenous Cu and Zn accumulation within the surface layers. More than 70% of the natural heavy metal content was originally in the residual fraction. However, this was the only fraction not influenced by the PS amendments. After PS input, the exogenous Cu was mainly detected in the fraction bound to organic matter (66.4%) within the PS200 0–5cm soil layer. Exogenous Zn was mainly distributed between the adsorbed fraction (36.7%) and the organic matter fraction (32.0%) within the PS200 0–5cm layer.

Effects of Pig Slurry Application and Crops on Phosphorus Content in Soil and the Chemical Species in Solution

The application of pig slurry rates and plant cultivation can modify the soil phosphorus (P) content and distribution of chemical species in solution. The purpose of this study was to evaluate the total P, available P and P in solution, and the distribution of chemical P species in solution, in a soil under longstanding pig slurry applications and crop cultivation. The study was carried out in soil columns with undisturbed structure, collected in an experiment conducted for eight years in the experimental unit of the Universidade Federal de Santa Maria (UFSM), Santa Maria (RS). The soil was an Argissolo Vermelho distrófico arênico (Typic Hapludalf), subjected to applications of 0, 20, 40, and 80 m3 ha-1 pig slurry. Soil samples were collected from the layers 0-5, 5-10, 10-20, 20-30, 30-40, and 40-60 cm, before and after black oat and maize grown in a greenhouse, for the determination of available P, total P and P in the soil solution. In the solution, the concentration of the major cations, anions, dissolved organic carbon (DOC), and pH were determined. The distribution of chemical P species was determined by software Visual Minteq. The 21 pig slurry applications increased the total P content in the soil to a depth of 40 cm, and the P extracted by Mehlich-1 and from the solution to a depth of 30 cm. Successive applications of pig slurry changed the balance between the solid and liquid phases in the surface soil layers, increasing the proportion of the total amount of P present in the soil solution, aside from changing the chemical species in the solution, reducing the percentage complexed with Al and increasing the one complexed with Ca and Mg in the layers 0-5 and 5-10 cm. Black oat and maize cultivation increased pH in the solution, thereby increasing the proportion of HPO42- and reducing H2PO4- species.

Forms and accumulation of copper and zinc in a sandy typic hapludalf soil after long-term application of pig slurry and deep litter

Successive applications of pig slurry and pig deep litter may lead to an accumulation of copper (Cu) and zinc (Zn) fractions in the soil profile. The objective of this study was to evaluate the Cu and Zn forms and accumulation in a Sandy Typic Hapludalf soil after long-term application of pig slurry and deep litter. In March 2010, eight years after initiating an experiment in Braço do Norte, Santa Catarina (SC), Brazil, on a Sandy Typic Hapludalf soil, soil samples were collected from the 0-2.5, 2.5-5.0, 5-10 and 10-15 cm layers in treatments consisting of no manure application (control) and with applications of pig slurry and deep litter at two levels: the single and double rate of N requirement for maize and black oat succession. The soil was dried, ground in an agate mortar and analyzed for Cu and Zn contents by 0.01 mol L-1 EDTA and chemically fractionated to determine Cu and Zn. The applications of Pig deep litter and slurry at doses equivalent to 90 kg ha-1 N increased the contents of available Cu and Zn in the surface soil layer, if the double of this dose was applied in pig deep litter or double this dose in pig slurry, Cu and Zn migrated to a depth of 15 cm. Copper is accumulated mainly in the organic and residual fractions, and zinc preferentially in the fraction linked to clay minerals, especially in the surface soil layers.

Nutrients in soil layers under no-tillage after successive pig slurry applications

Successive applications of pig slurry to soils under no-tillage can increase the nutrient levels in the uppermost soil layers and part of the nutrients may be transferred to deeper layers. The objective was to evaluate the distribution of nutrients in the profile of a soil after 19 pig slurry applications under no-tillage for 93 months. The experiment was conducted from May 2000 to January 2008 in an experimental area of the Federal University of Santa Maria, southern Brazil, on a Typic Hapludalf. The treatments consisted of pig slurry applications (0, 20, 40 and 80 m³ ha-1) and at the end of the experiment, soil samples were collected (layers 0-2, 2-4, 4-6, 6-8, 8-10, 10-12, 12-14, 14-16, 16-18, 18-20, 20-25, 25-30, 30-35, 35-40, 40-50 and 50-60 cm). The levels of mineral N, available P and K and total N, P and K were evaluated. The 19 pig slurry applications in 93 months promoted migration of total N and P down to 30 cm and available P and K to the deepest layer analyzed. At the end of the experiment, no increase was observed in mineral N content in the deeper layers, but increased levels of available P and K, showing a transfer of N, P and K to layers below the sampled. This evidences undesirable environmental and economic consequences of the use of pig slurry and reinforces the need for a more rational use, i.e., applications of lower manure doses, combined with mineral fertilizers.

Accumulation of phosphorus fractions in typic Hapludalf soil after long-term application of pig slurry and deep pig litter in a no-tillage system

In this paper we explore the accumulation of different phosphorus (P) fractions in soil submitted to successive applications of pig slurry (PS) and deep pig litter (DL). After 88 months of no-till crop cycles, soil samples were collected in the following treatments: control (C), PS applications equivalent to 90 and 180 kg N ha−1 (PS90 and PS180), and DL applications equivalent to 90 and 180 kg N ha−1 (DL90 and DL180). The cumulative application of P of the C, PS90, PS180, DL90 and DL180 treatment was 0, 303, 606, 825 and 1650 kg P ha−1, respectively. The soil samples were then submitted to P chemical fractionation. Successive applications of 303 and 606 kg P ha−1 in PS form and 825 and 1.650 kg P ha−1 in DL form increased P levels down to 20 cm depth, especially in the labile inorganic fraction extracted by anion exchange resin and 0.5 M NaHCO3 and to a lesser extent extracted by 0.1 M NaOH. Successive additions of PS180 and DL180 increased the levels of organic P extracted by 0.5 M NaHCO3, 0.1 M NaOH and 0.5 M NaOH, and successive applications of PS and DL caused P accumulation in the soil profile, especially in labile fractions. This increased the availability to plants, but also increases the potential for environmental contamination.

Dry matter production and nitrogen use efficiency of giant missionary grass in response to pig slurry application

This study assessed the effect of successive applications of pig slurry on the dry matter (DM) production and the nitrogen use efficiency of giant missionary grass along two years. A total of 55, 110, 165, 220 and 275 m³ of pig slurry/ha/year were applied in order to supply 100, 200, 300, 400 and 500 kg of total N/ha/year, respectively. These treatments were compared with the ammonium nitrate (200 kg of N/ha/year) source of N and with a control (no nitrogen application). Annually, nitrogen was applied in four divided doses, after the cutting of forage grasses, which takes place five times a year. The total DM yield did not differ between years and increased linearly as a function of pig slurry application, ranging from 2,698 kg of DM/ha/year (control) to 11,371 kg of DM/ha/year (275 m³ of pig slurry/ha/year). There was an increment of 32.3 kg of DM/m³ of pig slurry/ha or 17.7 kg of DM/kg of N/ha. The highest average daily DM accumulation rate (66.8 kg of DM/ha/day) was achieved with the highest pig slurry rate, from February/2007 to April/2008. Nitrogen use efficiency did not differ across pig slurry rates (19.0 kg of DM/kg of N), but it was lower than that obtained with ammonium nitrate (30.3 kg of DM/kg of N). The efficiency index of pig slurry ranged from 0.52 to 0.72.

Soil chemical properties related to acidity under successive pig slurry application

Pig slurry application as soil manure can alter the chemical properties of the soil and affect its acidity, modifying the environment for crop growth and development. The objective of this study was to evaluate the chemical properties related to soil acidity subjected to successive applications of pig slurry. The experiment was conducted in May 2000, in an experimental area of the Federal University of Santa Maria (UFSM) under no-tillage and lasted until January 2008. Nineteen surface applications of 0, 20, 40, and 80 m³ ha-1 of pig slurry were performed, during a period of 100 months and the soil sampled in the end (layers 0-2, 2-4, 4-6, 6-8, 8-10, 10-12, 12-14, 14-16, 16-18, 18-20, 20-25, 25-30, 30-35, 35-40, 40-50 and 50-60 cm). The application of pig slurry increased soil pH values, an effect that could reach the depth of 8 cm without affecting the potential acidity values. The applications also resulted in accumulation of Ca and Mg exchangeable levels in the surface layers, increasing base saturation and reducing Al saturation. Long-term applications induced an increase in organic matter in the deeper layers. However, the effect of this residue on the potential CEC was less significant and restricted to the surface layers.

ATRIBUTOS QUÍMICOS EM SOLOS DE PROPRIEDADES SUINÍCOLAS SUBMETIDOS A APLICAÇÕES SUCESSIVAS DE DEJETO DE SUÍNOS NO MUNICÍPIO DE BRAÇO DO NORTE, SANTA CATARINA

No estado de Santa Catarina (SC) os suínos são produzidos em sistema de criação intensiva e os dejetos gerados são usados como adubo orgânico em sistemas de cultivos anuais ou pastagens. O presente trabalho teve como objetivo avaliar as alterações de atributos químicos do solo, submetidos a aplicações sucessivas de dejetos de suínos em seis propriedades suinícolas no Município de Braço do Norte (SC), cultivadas com culturas anuais e pastagens. Em setembro de 2009 foram aplicados questionários para a caracterização do sistema produtivo de suínos e do manejo dos dejetos em seis propriedades nas Microbacias Rio Coruja/Bonito e Rio Cachorrinhos, no município de Braço do Norte (SC). Na mesma data foram coletadas amostras de solo, na camada de 0-20 cm, em áreas com culturas anuais e pastagem das propriedades e áreas de mata nativa. O solo foi seco, moído, passado em peneira e preparado para a análise de matéria orgânica, pH em água, P disponível, K trocável e, Al, Ca, Mg trocáveis e, Zn, Cu e Mn. As aplicações sucessivas de dejetos de suínos líquidos ao longo dos anos na maioria das propriedades, localizadas em duas Microbacias da Região Sul de Santa Catarina, elevaram os teores de fósforo disponível e de potássio trocável até muito alto e os de cobre, zinco e manganês até alto.

Nutrient transfer by runoff under no tillage in a soil treated with successive applications of pig slurry

High rates and successive applications of pig slurry can cause nutrient transfer by surface runoff. The aim of this study was to evaluate the importance of surface runoff in transferring nitrogen (N), phosphorus (P) and potassium (K) under a no tillage system and for successive applications of pig slurry. The research was carried out in the Agricultural Engineering Department of the Federal University of Santa Maria, Brazil, from 2002 to 2007 in a Typic Hapludalf soil. Pig slurry rates of 0, 20, 40 and 80m3ha−1 were applied, scattered on the surface, before the sowing of each species in a cultivation sequence. On average 119, 238 and 475kgha−1yr−1 of N; 102, 203 and 406kgha−1yr−1 of P and 43, 87 and 173kgha−1yr−1 of K were added, for rates of 20, 40 and 80m3ha−1 of pig slurry, respectively. Samples of water runoff from the soil surface were collected during the entire period and the minerals, N, P and K were determined. Successive applications of pig slurry decreased surface runoff. In relative terms, the K losses were higher than N and P. As regards total nutrients applied through pig slurry, losses through surface runoff were of 2.74, 1.61 and 1.37% of mineral N; 6.29, 5.01 and 3.51% of available P and 17.16, 9.01 and 11.14% of available K, for the three rates of applied pig slurry, respectively. Repeated applications of pig slurry on a no tillage managed soil caused losses of N, P and K from the soil through surface runoff, in the sequence: K>P>N. The losses of N and K are positively related to the volume of surface runoff, whereas the losses of P are positively related to the quantities of P added through pig slurry. Applications of pig slurry along the years decrease the surface runoff.

Copper, zinc and manganese in soils of two watersheds in Santa Catarina with intensive use of pig slurry

Systematic pig slurry application to crop soils may lead to the accumulation of heavy metals in regions with intensive pig raising. The aim of this study was to evaluate the accumulation of Cu, Zn and Mn in soils under systematic pig slurry application. For this purpose, soil samples were collected from two of the most representative watersheds of Santa Catarina where the predominant activity is pig raising. In each watershed, 12 properties were chosen to evaluate the different systems of pig husbandry (complete cycle (CC), farrowing (FaU) and finishing units (FiU)). Based on information of the producers, soil samples were collected in areas with and without systematic manure application. To determine the total Cu, Zn and Mn content in soils and manure, a methodology proposed by the Environmental Protection Agency of the United States (USEPA), method nº 3050B, was used. For the available heavy metal content, Cu and Zn was extracted with HCl 0.1 mol L-1 and Mn with KCl 1 mol L-1. Data were subjected to multivariate analysis, using the canonical discriminant analysis to identify the metals that best differentiate the soils studied within each swine housing system. Successive pig slurry applications cause an increase in Cu, Zn and Mn availability in the soil and this indicates the need for monitoring of the metal concentrations over time. The critical values of Cu in the soil can be reached and exceeded more rapidly than Zn. The results showed that the soil type may be one of the attribute underlying the determination of public policies in pig raising and waste management because soils such as Inceptisols were shown to be more prone to possible contamination since they may more rapidly reach total critical Cu levels.

Acúmulo e formas de cobre e zinco no solo após aplicações sucessivas de dejeto líquido de suínos

As aplicações sucessivas de dejeto líquido de suínos no solo podem aumentar os teores e alterar as formas de Cu e Zn no solo. O presente trabalho teve como objetivo estimar o acúmulo de Cu e Zn e suas formas em solo submetido a aplicações sucessivas de dejeto líquido de suínos, em sistema plantio direto com rotação de culturas. O trabalho foi desenvolvido em um Argissolo Vermelho distrófico arênico na área experimental do Departamento de Engenharia Agrícola da Universidade Federal de Santa Maria (RS). Os tratamentos consistiram na aplicação de 0, 20, 40 e 80 m³ ha-1 de dejeto líquido de suínos. Foram realizadas 17 aplicações de dejetos de maio de 2000 até o momento da coleta do solo, em outubro de 2006. Amostras de solo foram coletadas nas camadas de 0-2, 2-4, 4-6, 6-8, 8-10, 10-12, 12-14, 14-16, 16-18, 18-20, 20-25, 25-30, 30-35, 35-40, 40-50 e 50-60 cm, secas ao ar, passadas em peneiras de 2 mm e moídas em grau de ágata. Em seguida, foram preparadas e analisados os teores pseudototais após extração pelo método 3050B da EPA, disponíveis por meio da extração com HCl 0,1 mol L-1, além do fracionamento químico do Cu e do Zn. Nos dejetos de suínos foram determinados os teores pseudototais de Cu e Zn. As aplicações sucessivas de dejeto líquido de suínos no solo aumentaram os teores de Cu e Zn das camadas superficiais, com migração até 12 e 10 cm de profundidade, respectivamente. O Cu e Zn adicionados são acumulados no solo em formas biodisponíveis, sendo preferencialmente ligados às frações orgânica e mineral, respectivamente.

Frações de fósforo no solo após sucessivas aplicações de dejetos de suínos em plantio direto

O objetivo deste trabalho foi quantificar as frações de acumulação de fósforo em solo submetido a sucessivas aplicações de dejetos líquidos de suínos (DLS) em sistema de plantio direto. Em Santa Maria, RS, doses de 0, 20, 40 e 80 m³ ha-1 de DLS foram distribuídas a lanço por sete anos agrícolas, antes do plantio de cada cultivo de inverno ou verão, em Argissolo Vermelho arenoso, totalizando 0, 584, 1.168 e 2.336 kg ha-1 de P aplicado via dejetos. O solo foi coletado nas camadas 0-2, 4-6, 8-10, 14-16 e 20-25 cm, e submetido ao fracionamento químico de P. A adição do DLS ao solo durante sete anos aumentou o teor de P até 25 cm de profundidade, principalmente nas frações inorgânicas extraídas por resina trocadora de ânions, NaHCO3 0,5 mol L-1 e NaOH 0,1 mol L-1. As aplicações não aumentaram os teores de P orgânico extraído por NaHCO3 0,5 mol L-1, mas sim as frações orgânicas extraídas por NaOH 0,5 e 0,1 mol L-1. O DLS adicionado ao solo por longo período pouco afeta a partição de P em frações inorgânicas e orgânicas. As sucessivas aplicações de DLS aumentam o acúmulo de P em frações predominantemente lábeis no solo, o que representa um risco potencial para contaminação de águas superficiais e subsuperficiais.