Edicarlos Damacena de Souza

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.

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.

Produção de fitomassa de diferentes espécies de cobertura e suas alterações na atividade microbiana de solo de cerrado

The objective of this study was to evaluate the phytomass yield of nine species of cover crops of the soil and to verify the alterations in the activity and microbial biomass of Cerrado soil, in the State of Goias, Brazil. The work was developed from March to December, 2004, being sowed the following covering species: Avena strigosa, Cajanus cajan, Crotalaria juncea, Lablab purpureum, Pennicetum americanum, Raphanus sativus, Guizotia abyssinica, Canavalia ensiformis, Crotalatia spectabilis and an area in fallow considered with reference. In the occasion of the flower phytomass yield was determined and starting from August it leaves of this was conditioned in sacks of polyethylene to evaluate the decomposition tax, being in the soil for 120 days. During this period, in every month, they were evaluating the carbon of the microbial biomass and the microbial respiration of the soil. The Cajanus cajan, Pennicetum americanum, Canavalia ensiformis and Guizotia abyssinica are shown as the most promising species for phytomass yield, while the Avena strigosa, Crotalaria juncea and the Raphanus sativus present the smallest phytomass yield. The areas under Pennicetum americanum residues, Raphanus sativus, Crotalatia spectabilis and the fallow affect the carbon of the microbial biomass negatively. Area under resting provided to smallest phytomass yield, reduction in the carbon of the microbial biomass and larger loss of carbon, being this practice no suitable for the Cerrado region.

Distribuição de potássio e de raízes no solo e crescimento de milho em sistemas de manejo do solo e da adubação em longo prazo

Soil tillage systems can greatly influence potassium and root distribution in the soil and, as a result, affect corn growth and development. To improve the understanding of these interrelationships, a soil was analyzed after 18 years of cultivation under different management systems. A detailed soil sampling was carried out in a clayey Red Argisol (Udult) profile in the beginning of the grain filling stage of corn in the 2006/07 growing season. The experimental design consisted of a completely randomized scheme with two replicates, with the following treatments: conventional tillage (Con) and no-tillage (Dir) with potassium fertilization: along the rows (Fx), broadcast (Lan) and in stripes (Lin). Independently of the soil and fertilizer management, potassium formed gradients from the soil surface downwards and around the corn plant stem. The gradients, however, differed according to the soil management; concentrations were higher at the surface under no-tillage, regardless of the fertilization method. Maize roots were concentrated predominantly in the soil surface layer, with greater growth in no-tillage. Potassium uptake and maize growth were not associated with K distribution in soil and roots. The efficiency of K use by plants was increased by the broadcast application of potassium fertilizer, regardless of the tillage system.

Desenvolvimento e produção de bananeiras Thap Maeo e Prata-Anã com diferentes níveis de adubação nitrogenada e potássica

O objetivo desta pesquisa foi caracterizar o desenvolvimento e o rendimento de cultivares de bananeira no sudoeste de Goias e adequar os niveis de adubacao combinada de N e K. O experimento foi conduzido em Latossolo Vermelho distrofico, no municipio de Rio Verde, Goias. Os tratamentos consistiram em cinco doses crescentes e combinadas de N e K (N0/K0 - 0 kg ha-1 ano-1 de N e 0 kg ha-1 ano-1 de K; N1/K1 - 150 kg ha-1 ano-1 de N e 200 kg ha-1 ano-1 de K ; N2/K2 - 300 kg ha-1 ano-1 de N e 450 kg ha-1 ano-1 de K; N3/K3 - 450 kg ha-1 ano-1 de N e 600 kg ha-1 ano-1 de K; N4/K4 - 600 kg ha-1 ano-1 de N e 800 kg ha-1 ano-1 de K), aplicadas em duas cultivares de banana, Thap Maeo e a Prata-Ana. As avaliacoes realizadas nas bananeiras foram: altura das plantas, diâmetro do pseudocaule e numero de folhas aos 150 dias apos plantio (DAT) e na epoca do florescimento. As plantas foram avaliadas no florescimento e na colheita das bananeiras, observando os seguintes componentes de producao: intervalo em dias entre o plantio e o florescimento, numero de folhas na colheita, numero de pencas por cacho e frutos na segunda penca, comprimento do engaco e dos frutos na segunda penca, diâmetro do engaco e dos frutos na segunda penca e peso do cacho, engaco e dos frutos na segunda penca. Amostras foliares das bananeira foram realizadas no seu florescimento e foram analisadas para obter os teores de macro e micronutrientes. Com os dados dos componentes de producao, calcularam-se o indice de durabilidade das folhas e a taxa de crescimento absoluto do pseudocaule das bananeiras. Os resultados foram submetidos a ANOVA e regressao, e a comparacao de medias foi feita pelo teste de Tukey. Os atributos de desenvolvimento, a producao e os teores de macronutrientes e micronutrientes nas folhas da Thap Maeo e Prata-Ana foram influenciados pelas diferentes doses combinadas de N e K. O menor intervalo de dias entre o florescimento foi encontrado com as doses de 300 kg ha-1 de N e 450 kg ha-1 de K na Thap Maeo. Nao houve melhor combinacao das doses de N e K para os parâmetros de desenvolvimento, producao e teores foliares na Prata-Ana.

Variability and spatial correlation of aggregates and organic carbon in indian dark earth in Apuí region, AM

Having in mind the importance of knowing the variability and spatial correlation of soil properties in Indian Dark Earth (IDE), we evaluated in this study the variability and the spatial correlation of aggregates and carbon in an Ultisol under coffee cultivation in southern Amazonas. It was established a 48 x 88 m sampling grid spaced 06 x 08 m, totalling 88 sampling points. Then soil samples were collected at: 0.0-0.05, 0.05-0.10, and 0.10-0.20 m layers. The spatial variability of the Mean Weighted Diameter (MWD) attributes, aggregates > 2 mm, < 2 mm, bulk density (BD) and organic carbon (OC) was analyzed by adjusting the simple semivariograms, while spatial correlations of the OC with aggregates and BD were analyzed by cross-semivariogram. We could conclude that there was spatial dependence in the variables, wherein the largest ones were observed at 0.0-0.05 m, except for Mean Weighted Diameter (MWD) and aggregates greater than 2.00 mm with larger range of values in depth from 0.05-0.10 and 0.10-0.20 m. The mean weight diameter and aggregate class attributes greater than 2.00 mm had negative spatial correlation with organic carbon at 0.0-0.05 m, while the smaller aggregates than 2.00 mm classes and bulk density correlated positively with organic carbon at 0.0-0.05 m and 0.10-0.20 m.