Growth and chemical composition of legume‐based pasture irrigated with dairy farm effluent

An overview of the environmental effects of land application of farm effluents

“…Although effluent composition varies with source, treatment, and storage (Longhurst et al 2000b), it has been estimated that effluent generated by each dairy cow typically provides 5.9 kg N, 0.7 kg P, 5.4 kg K, 0.8 kg S, 2.2 kg Ca, 1 kg Mg, and 0.7 kg Na per year (Heatley 1996). Applying farm effluents to agricultural land generally improves crop yield, thereby reducing the need for chemical fertilisers (Lowe 1993;Cameron et al 1995;Bolan et al 2004a). Therefore, farmers can benefit from land application of farm effluent by reducing fertiliser costs.…”

“…To protect the environment and sustain production, numerous studies have been conducted to optimise farm-dairy effluent management through land application since the early 1970s (Longhurst et al 2000b;Bolan et al 2004a). Longhurst et al (2000b) summarised N content in farm-dairy effluent analysed between 1977 and 1997, and found that the mean N concentrations doubled from approximately 200 g N m-3 in the 1970s to 400 g N m-3 in the 1990s (Longhurst et al 2000b).…”

“…Regular application of farm effluents to agricultural land generally results in increased pasture yield, soil microbial activities and nutrient concentration, and often reduced soil acidity (Lowe 1993;Cameron et al 1995;Barkle et al 2000;Di & Cameron 2002;Hawke & Summers 2003;Bolan et al 2004a). Barkle et al (2000) reported that irrigation of farm-dairy effluent at high loading rates (3583 kg N ha -1 and 42 000 kg C ha -1 applied over a 3-year period) increased pH, microbial biomass, total C, and total N of a silt loam soil at a Waikato farm.…”

“…Dairy and pig farmers in New Zealand traditionally use waste stabilisation ponds (anaerobic followed by facultative pond) for treatment of farm effluent (containing urine, faeces, washing water, plus wasted feed in piggery effluent) before it is discharged to surface water (Hickey et al 1989;Heatley 1996;Sukias et al 2001;Bolan et al 2004a). The two-stage waste stabilisation ponds can remove significant amounts of suspended solids and organic contaminants (e.g., biochemical oxygen demand), but are not very effective in nutrient removal (Hickey et al 1989;Sukias et al 2001).…”

“…The fate and movement of farm-effluent-derived P has become an important issue in many countries, because effluent P is commonly accumulated in soils, and can enter waterways through runoff and contribute to surface water eutrophication (Sharpley 1995;Chardon et al 1997). Similarly, when farm effluent application is based on N loading, over-supply of other nutrients such as K may cause soil nutrient imbalance and animal health problems (Bolan et al 2004a). Odour Roberts et al (1992); Lowe (1993);Heatley (1996); Longhurst et al (2000b);Mikkelsen (2000); Sukias et al (2001); Di & Cameron (2002).…”