Ibanor Anghinoni

Managing grazing animals to achieve nutrient cycling and soil improvement in no-till integrated systems

Crop-livestock systems are regaining their importance as an alternative to unsustainable intensive farming systems. Loss of biodiversity, nutrient pollution and habitat fragmentation are a few of many concerns recently reported with modern agriculture. Integrating crops and pastures in no-till systems can result in better environmental services, since conservation agriculture is improved by system diversity, paths of nutrient flux, and other processes common in nature. The presence of large herbivores can positively modify nutrient pathways and soil aggregation, increasing soil quality. Despite the low diversity involved, the integration of crops and pastures enhances nature’s biomimicry and allows attainment of a higher system organization level. This paper illustrates these benefits focusing on the use of grazing animals integrated with crops under no-tillage systems characteristic of southern Brazil.

Distribuição do fósforo inorgânico em sistemas de manejo de solo

The intensity of the reactions of the phosphate fertilizer in the soil should vary in function of the different management systems. The study had the objective of evaluating the modifications in the inorganic fractions of P as affected by soil tillage and crop sequence. In May 1997, three soil layers of four long-term field experiments, involving no-tillage and conventional tillage with different crop sequences, were sampled. The total P and six fractions of inorganic P were evaluated. The medium content of total P was much higher than the native P. Total P increased in the upper soil layer under no-tillage. Available (resin and NaHCO3 0.5 mol L-1) and nonlabile inorganic P (HCl 1.0 mol L-1) were higher in the surface layer under no-tillage than in conventional tillage. The highest concentrations of inorganic P were moderately labile (NaOH 0.1 mol L-1). The crop sequences did not influence the fractions of inorganic P.

Atributos físicos do solo e rendimento de soja em sistema plantio direto em integração lavoura-pecuária com diferentes pressões de pastejo

The integration of farming and cattle production activities in no-tillage system areas with winter cover crops can be an income supplement for summer grain farmers. However, many of them are afraid of adopting this integration system, because of possible negative effects of animal treading on soil attributes, mainly of those related to soil compaction. This study was conducted: (1) to determine the alterations in the soil physical attributes promoted by animal treading; (2) to verify if the alterations in soil attributes due to animal treading affect soybean establishment and grain yield. The experiment was carried out with a Rhodic Hapludox (Oxisol), under black oat + ryegrass pasture grazed at different heights (10, 20, 30 and 40 cm) and an ungrazed area. After one cycle of animal treading there were no significant modifications in soil bulk density, porosity and compressibility at different grazing heights. However, soil density and compressibility were higher and the porosity lower in the grazed plots. The soybean population and grain yield were not affected by modifications in the soil physical attributes.

Resíduos de plantas de cobertura e mobilidade dos produtos da dissolução do calcário aplicado na superfície do solo

Cover plants have received extra attention due to their release of low molecular weight organic acids that form organic complexes with aluminum, calcium and magnesium. Besides neutralizing toxic aluminum, such compounds can increase the mobility in the soil profile of the dissolution products of lime applied on the soil surface. Objectives of this research were (a) to identify the low molecular weight organic acids found in different cover plant species and in soil solution, (b) to evaluate the effects of the residues, alone or together with surface lime application, in relation to acidity neutralization of subsoil layers in no-tillage systems, and (c) to verify the relation between organic acids of low molecular weight, released during the decomposition of plant residues, with the effect on soil acidity properties in the soil profile due to surface lime application. The experiment was carried out in a greenhouse in undisturbed Inceptisol (Haplumbrept) soil samples in columns, collected in a field experiment under no-tillage for five years. Nine treatments were applied: residue (10 Mg ha-1) of black oat (1), common vetch (2), oil seed radish (3), lime (13 Mg ha-1) (4), lime plus residue of black oat (5), of common vetch (6), of oil seed radish (7), and lime plus citric acid (0.91 Mg ha-1), (8) and no treatment (9), arranged in randomized blocks. The liquid chromatography method (HPLC) allowed an identification of the main low molecular weight organic acids in the plant residues. Trans-aconitic acid was the most important in black oat, malic acid in common vetch, and citric and malic acids in oil seed radish. It was not possible to detect organic acids in the percolate or soil solution. Plant residues had no effect on acidity neutralization in the deeper soil since the effects, alone or with lime application on the soil surface, were restricted to the soil surface layer (0-2.5 cm).

Estoques de carbono orgânico e de nitrogênio no solo em sistema de integração lavoura-pecuária em plantio direto, submetido a intensidades de pastejo

Sistemas de integracao lavoura-pecuaria tem um alto potencial de uso no sul do pais, especialmente em areas de soja sob plantio direto, com especies de cobertura no inverno. A conducao de sistemas de integracao com diferentes intensidades de manejo da pastagem resultara, ao longo do tempo, em estoques de C orgânico (CO) e de N diferenciados, decorrentes do aporte diferenciado de residuos. Este trabalho foi realizado para avaliar a evolucao dos estoques de CO e de N total (NT) e em fracoes fisicas da materia orgânica em solo submetido a diferentes intensidades de pastejo, em plantio direto. O experimento foi iniciado em 2001, em um Latossolo Vermelho distrofico, apos a colheita da soja. Os tratamentos constaram de alturas de manejo da pastagem (aveia-preta + azevem): 10, 20 e 40 cm, com bovinos jovens, e sem pastejo, seguido do cultivo de soja, em delineamento de blocos ao acaso. Amostras de solo foram retiradas no inicio do experimento (maio 2001), apos tres anos (maio de 2004) e apos seis anos (maio de 2007), para a avaliacao dos teores e dos estoques de CO e de NT. Intensidades de pastejo moderadas (20 e 40 cm de altura do pasto) promoveram aumento nos estoques de CO total, CO particulado, NT e N na materia orgânica particulada no solo, semelhante ao plantio direto sem pastejo. Na alta intensidade de pastejo (10 cm), houve reducao no estoque desses elementos, com degradacao da qualidade da materia orgânica.

Carbono orgânico e fósforo microbiano em sistema de integração agricultura-pecuária submetido a diferentes intensidades de pastejo em plantio direto

Integrated crop-livestock systems have attracted more interest in the last few years due to their capacity of improving stability and sustainability of agricultural systems as compared to more specialized production systems. Soil organic carbon content has been used as an indicator of soil sustainability and stability. In this sense, this study aimed to measure the stocks of total organic carbon fractions and phosphorus in the microbial biomass in a Rhodic Hapludox (Oxisol) under integrated crop-livestock system with different grazing intensities in the winter. Soil samples were collected in November 2006 in Sao Miguel das Missoes, state of Rio Grande do Sul, Brazil. The experimental area had been cultivated under no-tillage for 10 years before implementing the integrated system in 2001. The experimental design was completely randomized blocks with three replicates. The treatments consisted of grazing intensities represented by sward heights of 10, 20 and 40 cm during the pasture cycle in winter. This pasture was composed of a black oat (Avena strigosa Schreb) and Italian ryegrass (Lolium multiflorum Lam.) mix, and a control area with no grazing. Total and particulate organic matter (POM) carbon stocks, phosphorus and carbon content in the microbial biomass, as well as microbial biomass activity were evaluated. The total organic stocks carbon were not affected by grazing intensities; however, the stocks of POM carbon were smaller in soils under the highest grazing intensity. The microbial biomass was stimulated at the highest grazing intensity, in which greater root growth was observed. The phosphorus content in the microbial biomass increased linearly with the decrease of the grazing intensity, while an inverse pattern was observed for the microbial biomass. Particulate organic matter carbon was more sensitive to changes in soil organic carbon under the experimental pasture management.

Evolução de atributos físicos de solo em sistema de integração lavoura-pecuária

The objective of this work was to assess the effect of sward height and successive grazing cycles over soil physical attributes in an integrated crop-livestock system. The experiment was established in 2001, in the Planalto Medio region, RS, Brazil, in a Rhodic Hapludox (Oxisol), with annual ryegrass (Lolium multiflorum) intercropped with black oat (Avena strigosa), under continuous grazing, during the winter, and single cropped soybean (Glycine max) during the summer. The treatments consisted of different grazing intensities, determined by sward height (10, 20, 30, and 40 cm), and a no-grazing area was used as a control. Soil bulk density and soil porosity were evaluated at the end of the grazing and soybean cycles, as well as soil resistance to mechanic penetration and aggregate stability in the seventh year of the experiment. No significant differences were found on soil bulk density and soil porosity after seven years under crop-livestock integration. Soil resistance to penetration is higher on the superficial layer after the grazing cycle. Soil aggregation increases in grazing areas, regardless of grazing intensities.

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.

Sorção de fósforo em função do teor inicial e de sistemas de manejo de solos

The sorbed P/ P in solution relation of the soil may be affected by the previously sorbed P (Ppre) content and by soil management systems. The objective of this study was to evaluate modifications in the maximum P sorption capacity (Pmax) and the constant related to the colloid linkage energy (k) of the Langmuir isotherm caused (a) by the inclusion of Ppre, and (b) by different soil tillage methods and crop sequences. In May 1997, samples of two Oxisols (Very clayey Hapludox and Clayey Hapludox) and an Ultisol (Paleudult) were collected in three soil layers (0-2.5, 2.5-7.5 and 7.5-17.5 cm) of three field experiments, installed from 1979 on, under conventional and no tillage systems with different crop sequences. The samples were equilibrated with eight P levels in 0.001 mol L-1 CaCl2 solution. After 16 h of shaking, the P content in the supernatant was determined. The sorbed and solution P data were adjusted to the Langmuir equation, and Pmax and k parameters determined by considering Ppre or not. On average, the inclusion of Ppre in the Langmuir equation increased the k value 2.9 times, but did not affect Pmax in the very clayey Hapludox, which increased in all soil layers of the clayey Hapludox and in the surface layer of the Paleudult. Pmax was little affected by the soil tillage methods, crop sequence or soil layers.

Fósforo da biomassa microbiana e atividade de fosfatase ácida após aplicação de fosfato em solo no sistema plantio direto

A atividade de fosfatases e a biomassa microbiana sao fundamentais no ciclo do fosforo no solo e no seu fornecimento as plantas. Este trabalho analisa os reflexos da aplicacao de fosforo na atividade de fosfatase acida e no acumulo de fosforo na biomassa microbiana em solo no sistema plantio direto. Em janeiro de 2000, coletaram-se amostras da camada de 0-10 cm nos tratamentos de doses acumuladas de 0, 130, 180, 260, 360, 540, 720, 980 e 1.240 kg ha-1 de P2O5 em seis anos de cultivo de um experimento em Latossolo Vermelho distroferrico tipico muito argiloso. Coletaram-se tambem amostras do solo sob mata nativa, em area proxima ao experimento. Determinaram-se os teores de fosforo na biomasssa microbiana, a atividade de fosfatase acida, o fosforo total, orgânico e disponivel, e o carbono orgânico total. O solo sob mata nativa apresentou os maiores valores de fosforo microbiano, de atividade de fosfatase acida e de fosforo orgânico. A atividade de fosfatase acida nao foi influenciada pela adicao de fosfato. O fosforo contido na biomassa microbiana aumentou com a aplicacao recente de fosfato e nao foi influenciado pelo fosforo do solo de aplicacoes anteriores.