Claudete Reisdorfer Lang

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.

Grazing intensity and nitrogen in oat dry mass and yield of corn crop livestock systems.

This study aimed to evaluate the impact of different grazing intensities and nitrogen fertilization applied on oats and its effect upon maize cultivated in succession in a no tillage system. The experiment was carried out at Abelardo Luz municipality during the winter and summer seasons of 2004/2005. The experimental design was a completely randomized block in a split-plot arrangement with four replicates. Treatments were ?ve different grazing intensities, represented by utilization periods in an oat culture grazed for 0, 3, 6, 9 and 12 weeks, and at sub-plot level nitrogen doses were applied at 0 and 150 kg/ ha. The availability and residual dry matter of oat was evaluated each three weeks after the beginning

Viabilidade econômica da produção de novilhas leiteiras a pasto em sistema de integração lavoura-pecuária

O objetivo deste trabalho foi avaliar a rentabilidade do sistema de integracao lavoura-pecuaria (ILP), em comparacao ao cultivo de cereais de inverno e de plantas de cobertura para o plantio direto de soja e milho no verao. Foram comparados dados simulados de sistema agricola tradicional com producao de graos de milho e soja, no verao, e cultivo de trigo e plantas de cobertura do solo, no inverno; e dados de um trabalho publicado em que foram avaliadas combinacoes de pastagens (diversificadas ou puras) e categorias de animais (leves ou pesados), com producao de graos de milho e soja, no verao, e pastejo no inverno. A analise economica foi realizada com base nos resultados experimentais e simulada para uma propriedade de 100 ha. A ILP com recria de novilhas leiteiras em pastagens anuais de inverno, em substituicao ao sistema convencional com cultivo de cereais de inverno e plantas de cobertura de solo para o plantio direto, e a alternativa mais rentavel aos produtores.

Potencial do capim-quicuio em manter a produção e a qualidade do leite de vacas recebendo níveis decrescentes de suplementação

Aiming to study alternatives to extensification, it was evaluated the effect of supplement supply reduction (levels of 100, 65, 45 and 20% of the total requirements for production) and the possibility of its substitution by kikuyu grass on milk production and composition. The trial was performed using a completely randomized block design with three replicates, using the continuous and variable stocking rate grazing method aiming to keep the sward height at 20 cm. Individual and per hectare milk production presented positive linear response with the supplementation level. The qualitative milk components were not modified by reducing the use of supplements, however, daily productions of crude protein and fat by the animal varied with the supplementation levels. Cows grazing kikuyu grass do not maintain their milk production when supplement offer is reduced.

Habilidade competitiva de capim aries com plantas daninhas no estabelecimento: características morfológicas

Objetivou-se com esta pesquisa avaliar a competicao interespecifica do Panicum maximum cv. Aries no periodo de estabelecimento, sendo os fatores estudados os niveis de sombreamento e de nitrogenio. Os niveis de sombreamento provocados pelas plantas daninhas foram de 0%, ate 40%, ate 70% e 60%, na ausencia e na presenca de nitrogenio. Foram analisados: altura de planta, dinâmica de perfilhamento, indice de area foliar (IAF), materia seca, material senescente de folha e intensidade de competicao relativa (ICR) de P. maximum cv. Aries com as plantas daninhas. Os dados foram submetidos a testes de homogeneidade de variâncias e normalidade de residuos, e entao realizados analises de variância (ANOVA), teste de media (Tukey) ao nivel de 5% de probabilidade e regressao. As caracteristicas morfologicas e produtividade do P. maximum cv. Aries apresentaram melhores respostas em condicao de nao interferencia das plantas daninhas. O nitrogenio contribuiu para um melhor desenvolvimento de P. maximum cv. Aries, contudo no tratamento de convivio com as plantas daninhas sem corte houve o dominio sobre o P. maximum cv. Aries. O corte realizado nas plantas daninhas promoveu a diminuicao da intensidade de competicao interespecifica. A condicao variavel de sombreamento no tempo exprime diferentes respostas morfologicas em comparacao com uma condicao homogenea, interferindo principalmente na velocidade de estabelecimento do P. maximum cv. Aries.

DINÂMICA DA DECOMPOSIÇÃO E LIBERAÇÃO DE NUTRIENTES DA PALHADA DE AVEIA PRETA E NABO FORRAGEIRO CORTADAS EM DIFERENTES ESTÁGIOS DE DESENVOLVIMENTO

The dynamics of nutrient (N, P, K, Ca and Mg) decomposition and release from winter litter mulching of black oat (Avena strigosa Schreb) and turnip (Raphanus sativus L.) were studied during a 8,5 month period. Factorial randomized blocks were used as the experimental design. A combination of the two mentioned soil mulchings cut at three development stages was used. These were: vegetative (94 days), flowering (103 days) and full flowering (116 days). Harvested material was put into small nylon bags that were scattered on the soil and recovered after five periods of four weeks each for content examination. Results were submitted to variance and regression analysis. Adjustment to a mathematical model indicating mass loss was made according to BADRE et alii, (1998). The experimental model relates the mass decomposition rate as well as nutrient release as a quadratic function on time (t). the mathematical model used was: M(t) = M(o). Exp. T (a t + b). The dry mass production presented no differences between species. It was higher under flowering and full flowering conditions when compared to the vegetative phase for oat as well as for turnip (p 0,05). The carbon/nitrogen (C/N) ratio and lignin, silica and cutin (ADF) were both different between the different phases (p 0,05). In terms of nutrient release the exponential model used was highly significant (p < 0,01) for all nutrients independently of the species studied and their development phases.