Rhizobium specificity in Leucaena

Knowledge of the specificity of Leucaena for strains of rhizobia that form effective N-fixing associations is confined mostly to Leucaena leucocephala. However, recognition of the agroforestry potential of other species has stimulated an assessment of rhizobial requirements of all 22 species in the genus. In N-free systems, Leucaena exhibits very significant genotype interactions with rhizobial strains that form effective symbioses. Specificity for effectiveness was observed both between and within species. In two glasshouse experiments, all tested rhizobial strains formed nodules with all species, but the level of effectiveness, based on plant dry weights, ranged from totally ineffective to more effective than plants supplied with mineral nitrogen. Plant dry weight and nitrogen content responses were used to place host genotypes into three broad similarity groups. No strain of Rhizobium was universally effective on all host accessions, although several reasonably wide spectrum strains were identified and recommended for field testing. Need-forinoculation field experiments should be used to assess the effectiveness of background rhizobial strains and when found to be unsatisfactory, newly planted Leucaena should be inoculated with suitable Rhizobium. Strain CB3060 has demonstrated an intrinsic competitive ability in the field, but other elite strains (CB3126 and LDK4), identified in glasshouse trials require field testing. The main factors affecting nodulation and N2 fixation are identified as: 1) soil acidity and phosphorus deficiency; 2) high levels of nitrate-N in the soil; 3) moisture stress combined with high temperatures; and 4) the effects of defoliation. The importance of these observations to establishment of Leucaena in new areas, especially in acid soils, is discussed in relation to selection of suitable strains for successful early nodulation and plant growth. (Résumé d'auteur

THE INCOME AND CONSUMPTION EXPERIENCES OF A SAMPLE OF FARM FAMILIES

The way in which the consumption of farm families is adjusted to fluctuations in income has important implications at the national, regional and farm levels. In this paper, hypotheses about the consumption of farm families are examined using data from 16 families in a wheat-sheep region of New South Wales for the eight-year period 1968/69 to 1975/76. The results of the study indicate that lagged effects are important in explaining consumption by farm households. It was not possible to partition these lag effects between partial adjustment and normal income influences. Estimates of the short-run (one-year) marginal propensity to consume (mpc) were quite low, ranging from 0.13 to 0.16. The best estimates of the long-run mpc ranged from 0.19 to 0.25

THE INCOME AND CONSUMPTION EXPERIENCES OF A SAMPLE OF FARM FAMILIES

The way in which the consumption of farm families is adjusted to fluctuations in income has important implications at the national, regional and farm levels. In this paper, hypotheses about the consumption of farm families are examined using data from 16 families in a wheat-sheep region of New South Wales for the eight-year period 1968/69 to 1975/76. The results of the study indicate that lagged effects are important in explaining consumption by farm households. It was not possible to partition these lag effects between partial adjustment and normal income influences. Estimates of the short-run (one-year) marginal propensity to consume (mpc) were quite low, ranging from 0.13 to 0.16. The best estimates of the long-run mpc ranged from 0.19 to 0.25.Consumer/Household Economics,

The Consumption Behaviour of Farmers: a review of the evidence

Over recent years there has been marked instability in incomes earned from farming. The instability, which affects the economy generally, is transmitted partly through the consumption spending of farmers. A conventional view of the short-run marginal propensity to consume of farmers, supported by some analyses of aggregate data, is that it is zero. It is argued that this view is implausible on theoretical grounds, that the analysis giving rise to this view used aggregate data which contained serious flaws, and that evidence from micro-studies and other macro level analyses present a more realistic assessment that the short-run mpc of farmers is not zero but likely to be lower than that of non-farmers. A non-zero mpc has implications for how the farm sector interacts with the rest of the economy and is incorporated in models of the economy

The Consumption Behaviour of Farmers: a review of the evidence

Over recent years there has been marked instability in incomes earned from farming. The instability, which affects the economy generally, is transmitted partly through the consumption spending of farmers. A conventional view of the short-run marginal propensity to consume of farmers, supported by some analyses of aggregate data, is that it is zero. It is argued that this view is implausible on theoretical grounds, that the analysis giving rise to this view used aggregate data which contained serious flaws, and that evidence from micro-studies and other macro level analyses present a more realistic assessment that the short-run mpc of farmers is not zero but likely to be lower than that of non-farmers. A non-zero mpc has implications for how the farm sector interacts with the rest of the economy and is incorporated in models of the economy.Consumer/Household Economics,