Comparing irrigated biodynamic and conventionally managed dairy farms. 1. Soil and pasture properties

Abstract

Ten paired irrigated dairy farms under biodynamic (BD) and conventional (CV) management were compared over a 4-year period (1991–94). The paired farms were located in the irrigation districts of northern Victoria and southern New South Wales and were matched for soil type, climate, cattle breed and farm area. Farms had been practising BD principles for an average of 16 years before the commencement of the study and had not received phosphorus (P) fertiliser for an average of 17 years. The effects of farm management on soil chemical and biological properties and the nutritive properties and botanical composition of pasture were examined at varying sampling times during the study. Soil Olsen extractable P concentrations were consistently 2–3 times higher under CV management at various sampling depths (mean = 22 mg/kg, 0–10 cm), and were generally marginal under BD management in the surface 10 cm (mean = 8.5 mg/kg). Low soil extractable P concentrations were also reflected in consistently lower mean pasture P concentrations under BD management (0.25 compared with 0.35% on CV farms). Lower soil and pasture P concentrations under BD management were the result of a large negative P balance across BD farms (–17 kg P/ha.year). A mean negative P balance under BD management was a result of low P imports (2 kg P/ha.year) in comparison with large quantities of P (19 kg P/ha.year) effectively lost from the farming system through animal products, estimated losses in water runoff and slowly reversible soil P reactions. These results suggest that greater P imports are required to ensure the future sustainability of BD dairy pasture farming systems. There were few differences in soil biological properties, with earthworm weights significantly higher under CV management, but no difference in soil organic carbon, humus concentration, the weight of the organic mat or microbial biomass, between the two management systems.

Effects of Organic and Inorganic Fertilizers on the Growth and Yield of Physic Nut (Jatropha curcas)

“…This agrees with [1] that poultry droppings contain more plant nutrients than all other fertilizers (organic/inorganic) and [3] that poultry manure increase the chlorophyll content of the leaves causing the soil to release some of its store plant nutrients in a form that it can be easily absorbed by plants. …”

“…plant growth, while poultry manure also increases plant growth and crop yield making the leaves greenish and fresh thereby causing the soil to release some of its store of plant food in a form that it can be absorbed by plants easily [3].…”

Plant and microbial strategies to improve the phosphorus efficiency of agriculture

“…However, high P-balance efficiency is often only achieved in low input, low production farming systems (e.g. McIvor et al 2011;Burkitt et al 2007), or in productive agriculture on soils that have intrinsically low P-buffering capacity (e.g. sands), or where P-buffering capacity is low because sorption sites for P are close to saturation and soil P fertility is relatively high (e.g.…”

Can Organic Crop Production Feed the World?

“…On grazed organic systems in southern Australia, where legume-based annual pastures are rotated with crops, P can become the yield-limiting element (Ryan et al, 2004). Similarly, permanent clover-based pastures of biodynamic farms in Australia show lower production than conventional, which is also ascribed to lower inputs of nutrients, particularly of P (Burkitt et al, 2007a;b). A correct view on this is that over the long-term, less can be taken out of a system if less is put in (Goulding, 2007).…”