Milton da Veiga

Integração lavoura-pecuária: intensificação de uso de áreas agrícolas

Crop-livestock is a production system that succeeds, at the same area, pastures to animal production and vegetal crops, especially cereals. The objective of this work was to discuss the major presuppositions and characteristics of the crop-livestock system in Southern Brazil, and its effects on the soil quality and animal and vegetal yield. This production system can result in some advantages to farmers such as increase of rent per area, higher diversification, decrease of economic hazards and production costs. Moreover, the crop-livestock system can show biological advantages such as biodiversity increase and improved soil quality. Among the disadvantages, it can point out the possibility of superficial soil compaction in inappropriate pasture management. To success of crop-livestock system some presuppositions must be considered, such as crop rotation, use of no-tillage system, correction of soil acidity and fertility, use of improving vegetal and animal genotypes and, mainly, adequate pasture management.

Short and long-term effects of tillage systems and nutrient sources on soil physical properties of a Southern Brazilian Hapludox

Soil tillage promotes changes in soil structure. The magnitude of the changes varies with the nature of the soil, tillage system and soil water content and decreases over time after tillage. The objective of this study was to evaluate short-term (one year period) and long-term (nine year period) effects of soil tillage and nutrient sources on some physical properties of a very clayey Hapludox. Five tillage systems were evaluated: no-till (NT), chisel plow + one secondary disking (CP), primary + two (secondary) diskings (CT), CT with burning of crop residues (CTb), and CT with removal of crop residues from the field (CTr), in combination with five nutrient sources: control without nutrient application (C); mineral fertilizers, according to technical recommendations for each crop (MF); 5 Mg ha-1 yr-1 of poultry litter (wetmatter) (PL); 60 m3 ha-1 yr -1 of cattle slurry (CS) and; 40 m3 ha-1 yr -1 of swine slurry (SS). Bulk density (BD), total porosity (TP), and parameters related to the water retention curve (macroporosity, mesoporosity and microporosity) were determined after nine years and at five sampling dates during the tenth year of the experiment. Soil physical properties were tillage and time-dependent. Tilled treatments increased total porosity and macroporosity, and reduced bulk density in the surface layer (0.00-0.05 m), but this effect decreased over time after tillage operations due to natural soil reconsolidation, since no external stress was applied in this period. Changes in pore size distribution were more pronounced in larger and medium pore diameter classes. The bulk density was greatest in intermediate layers in all tillage treatments (0.05-0.10 and 0.12-0.17 m) and decreased down to the deepest layer (0.27-0.32 m), indicating a more compacted layer around 0.05-0.20 m. Nutrient sources did not significantly affect soil physical and hydraulic properties studied.

Organic carbon content and susceptibility to compaction of Hapludalf and Hapludox soils.

Organic matter accumulation can increase soil resistance to compaction, decreasing the compaction magnitude or its effects. The objective of this study was to establish the effect of soil organic matter accumulation on the compressibility index, which corresponds to soil susceptibility to compaction. The study was performed using samples collected from a Hapludalf and a Hapludox soils in southern Brazil, both having a significant variation in soil organic carbon (SOC) content. Soil compressibility tests were performed under confined conditions, in a uniaxial apparatus by using normal loads of 12.5, 25, 50, 100, 200, 400, 800 and 1600 kPa, and the compressibility index (Cc) was calculated. Soil organic carbon content, bulk density, porosity and water saturation degree were determined too. Results show that soil organic matter content affects the soil compressibility index, however the magnitude and type of effect are dependent upon soil texture and effects associated to soil water retention, cohesion, and bulk density.

Atributos químicos de um Latossolo Vermelho após nove anos de aplicação de dejeto líquido de suínos

The objective of this study was to evaluate the pig slurry application effects on chemical attributes of a Hapludox soil managed under no-tillage system. Treatments consisted of 50, 100 and 200 m3 ha-1 per year of pig slurry application, and a control with replacement of P and K exported through harvested grains. Attributes related to soil chemical reaction, exchange complex, and nutrient contents were determined in soil samples collected in the ninth year of experimentation from 0 - 0.025, 0.025 - 0.05, 0.05 - 0.10, 0.10 - 0.20, 0.20 - 0.40 and 0.40 - 0.60 m soil depths. The continuous application of high doses of pig slurry on the Oxisol surface under no-tillage acidifies the soil and increases Al, P, Cu, and Zn contents down to 0.2-m depth, and K levels down to 0.6-m depth.

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 200m3 ha(-1)year(-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 0-5 cm soil layer for the 50 and 100 m3 ha(-1) year(-1) (PS50 and PS100) treatments, and up to 10-15 cm for the 200 m3 ha(-1)year(-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 0-5 cm soil layer. Exogenous Zn was mainly distributed between the adsorbed fraction (36.7%) and the organic matter fraction (32.0%) within the PS200 0-5 cm layer.

Análise ambiental do uso de fontes de nutrientes associadas a sistemas de manejo do solo

Os modelos matematicos de analises sao ferramentas integradoras que podem contribuir para uma avaliacao mais eficaz do potencial poluente de dejetos quando dispostos no ambiente. Utilizou-se, para avaliar os impactos do uso de fontes de nutrientes, um experimento conduzido durante nove anos, em um Nitossolo Vermelho Distrofico, com uma combinacao de aplicacao de cinco fontes de nutrientes (tres fontes orgânicas, uma mineral e uma testemunha) associadas a cinco sistemas de manejo do solo, com delineamento em blocos subdivididos e tres repeticoes. Os atributos utilizados foram os teores no solo de Zn e Cu disponiveis, formas labeis de P, indice de diversidade da mesofauna edafica, teores de carbono e nitrogenio no solo, alem de dois questionarios de opiniao sobre o impacto ambiental do uso dos dejetos e dos sistemas de manejo do solo. Na avaliacao se usou um modelo cujas saidas, para cada fonte de nutriente dentro de cada sistema de manejo do solo, foram figuras triangulares e a area das mesmas, com intervalo de confianca a nivel de 90%. As fontes orgânicas exerceram efeitos diferenciados quanto ao aspecto ambiental, em que o dejeto liquido de suinos apresentou o pior desempenho. O indice de risco, dentre os tres indices que compoem o aspecto ambiental, demonstrou ser o mais critico ao ambiente, considerando-se os parâmetros e pesos utilizados.

SPECTROSCOPIC QUANTIFICATION OF SOIL PHOSPHORUS FORMS BY 31P-NMR AFTER NINE YEARS OF ORGANIC OR MINERAL FERTILIZATION

Long-standing applications of mineral fertilizers or types of organic wastes such as manure can cause phosphorus (P) accumulation and changes in the accumulated P forms in the soil. The objective of this research was to evaluate the forms of P accumulated in soils treated with mineral fertilizer or different types of manure in a long-term experiment. Soil was sampled from the 0-5 cm layer of plots fertilized with five different nutrient sources for nine years: 1) control without fertilizer; 2) mineral fertilizer at recommended rates for local conditions; 3) 5 t ha-1 year-1 of moist poultry litter; 4) 60 m3 ha-1 year-1 of liquid cattle manure and 5) 40 m3 ha-1 year-1 of liquid swine manure. The 31P-NMR spectra of soil extracts detected the following P compounds: orthophosphate, pyrophosphate, inositol phosphate, glycerophosphate, and DNA. The use of organic or mineral fertilizer over nine years did not change the soil P forms but influenced their concentration. Fertilization with mineral or organic fertilizers stimulated P accumulation in inorganic forms. Highest inositol phosphate levels were observed after fertilization with any kind of manure and highest organic P concentration in glycerophosphate form in after mineral or no fertilization.

Atributos de solo e de plantas afetados pelo manejo da pastagem anual de inverno em sistema de integração lavoura-pecuária

Continued use of the crop-livestock system in agricultural areas can promote changes in soil physical attributes, as well as affect the productivity of crops grown in rotation with pasture. The aim of this study was to evaluate the effects of methods of sowing and the interval between the withdrawal and desiccation of pasture on soil physical attributes, aboveground biomass of pasture and productivity of crops sown in succession. It was conducted an experiment in a rural property in Campos Novos, which uses the crop-livestok system, with the following treatments: two types of pasture seeding in autumn (direct seeding without and with subsequent soil harrowing), allocated in main plots, and four intervals of removing animals from the pasture before desiccation (removal of the animals at 28, 14 and 1 day before the desiccation and control, without grazing), allocated as subplots. It was determined the aboveground biomass of pasture, the soil physical attributes after desiccation of grassland and yield of soybeans and corn. The form of winter pasture seeding does not affect the soil physical attributes and crop productivity, while increasing the interval between the withdrawal and desiccation of winter pasture increases the production of the aboveground biomass of the pasture.

Desempenho da cultura do feijão após diferentes formas de uso do solo no inverno

O uso e manejo do solo durante o inverno pode alterar as caracteristicas fisicas do solo, a cobertura remanescente e o desempenho da cultura semeada em sucessao. O objetivo deste trabalho foi avaliar o efeito de formas de uso do solo no inverno sobre essas variaveis, semeando-se a cultura do feijao em sucessao, manejada em plantio direto. Na safra 2007/08, foram conduzidos tres experimentos na regiao do Planalto Norte Catarinense, onde foram avaliadas cinco formas de uso do solo durante o inverno: 1) consorcio de aveia preta + azevem + ervilhaca + trevo vesiculoso manejado sem pastejo e sem adubacao nitrogenada (consorcio cobertura); 2) o mesmo consorcio, com pastejo e com 100kg ha-1 de N em cobertura (pastagem com N); 3) o mesmo consorcio, com pastejo e sem adubacao nitrogenada (pastagem sem N); 4) nabo forrageiro, sem pastejo e sem adubacao nitrogenada (nabo forrageiro); e 5) pousio, sem pastejo e sem adubacao nitrogenada (pousio). O consorcio cobertura proporciona maior quantidade de palha para o cultivo de feijao em sucessao, mas as formas de uso do solo no inverno estudadas nao afetam expressivamente a densidade e a macroporosidade do solo. O uso do solo no inverno com pastagem anual em sistema integracao lavoura-pecuaria, coberturas de solo e pousio nao afeta o desempenho da cultura do feijao semeada em sucessao, manejada em plantio direto.

Soil physical attributes in forms of sowing the annual winter pasture and intervals between grazing

The sowing of winter pastures in areas used for summer grain production and their management under direct cattle grazing can cause changes in soil physical attributes, whose intensity depends on the degree of soil mobilization, grazing interval, stocking rate and weather. To study these aspects it was conducted over four years an experiment in a randomized block with split plots design and four replications. In the main plots were applied two forms of sowing the annual winter pasture (direct seeding and seeding + harrowing) and, in the subplots, four intervals between grazing (7, 14 and 28 days and ungrazed). Undisturbed soil cores were sampled at the end of each grazing cycle, in the 0-0.05 m layer to determine the saturated hydraulic conductivity and aggregate stability and in the layers of 0-0.05, 0.05-0.10, 0.10-0.15 and 0.15-0.20 m depth to determine bulk density and classes of soil pores. The direct seeding of annual winter pasture increases hydraulic conductivity and reduces soil bulk density in relation to seeding + harrowing while dairy cows trampling increases soil density and reduces macroporosity in the most superficial soil layer. The variation in climatic conditions among grazing cycles affects the soil physical attributes more markedly than forms of sowing and intervals between grazing of the annual winter pasture.