Rates of dairy shed effluent applied to pastures on clay soils in Northland

Abstract

Dairy shed washdowns were collected and sprayed on to pasture at two rates over four consecutive milking seasons from 1972 to 1976 on a farm near Whangarei. The high rate of effluent disposal (120000 l/ha every 21 days) increased mean annual herbage yields by 43% and the lower rate of disposal (60000 l/ha every 21 days) increased yields by 27%. Yield increases were obtained to effluent application throughout each milking season, provided pasture growth was not limited by moisture stress. The responses are mainly attributed to the nutrient content of the effluent since a water-only (60000 l/ha every 21 days) treatment did not increase herbage yields in any milking season. The nutrie t content and the amounts of nutrients returned in the effluent treatments varied considerably within and between milking seasons. The mean amounts of N, P, and K returned annually in the low rate of effluent disposal were 156, 46, and 348 kg of nutrient/ha. Soil-test levels of K increased significantly (P < 0.05) on plots receiving effluent and although other nutrients such as Ca and Mg also increased, relative to plots receiving water-only, the effects were not always statistically significant. It is concluded that dairy shed effluent is a valuable on-farm source of plant nutrients, capable of substantially increasing herbage yields throughout the milking season and at the same time its application increases the soil K reserves. The results have indicated that effluent can be applied at moderately high rates to Northland clay soils over a number of years without adversely affecting pasture composition or vigour.

Farm dairy effluent: A review of published data on chemical and physical characteristics in New Zealand

“…Much of the earlier New Zealand-based research on FDE was carried out during a 4-year study on a Northland farm from 1972 to 1976 (Goold 1980). High and low application rates of FDE (12 mm and 6 mm applied every 21 days, respectively) were compared with water only (at the low rate) and control treatments.…”

An analysis of environmental and economic implications of nil and restricted grazing systems designed to reduce nitrate leaching from New Zealand dairy farms. II. Pasture production and cost/benefit analysis

“…Various studies have shown that the return of animal excreta to pasture, as urine, dung, slurry, or effluent, can have a beneficial effect on DM production (e.g., Goold 1980;Hogg 1981;Ledgard & Saunders 1982;Williams & Haynes 1995). However, as mentioned above, when excreta are returned to pasture in concentrated urine and dung patches, the quantities of N returned greatly exceed the plant requirements in the area of the patch.…”

“…In a New Zealand grass/clover pasture, Goold (1980) measured an increase in DM production following spray irrigation of farm dairy effluent on a Waikare clay soil. Averaged over a 4-year period, annual DM production increased by 27% and 43% following effluent application every 21 days at 6 mm ha • (low) or 12 mm ha" 1 (high), respectively.…”

“…Assuming an N content in FDE in the unfertilised farmlet of 0.05% (Goold 1980;Roberts et al 1992), 560 000 and 790 000 1 ha^1 or 56 mm and 79 mm effluent would have to be applied, respectively. As it is recommended that the amount of effluent applied at any one time should not exceed 25 mm (Heatley 1996), it was assumed that the effluent N was returned in two and three equal split applications, for the average farm and the DRC farmlet, respectively.…”

Influence of biogas-digester effluent on crop growth and soil biochemical properties under rotational cropping

“…More information is available on the disposal of other agricultural wastes. For example, silage effluent (Cooper 1977) and dairyshed effluent (Goold 1980) were found to be valuable sources of nutrients for grassland pastures. Large amounts of cattle-feedlot wastes, applied over a 5-year period, were shown to have no deleterious effects on soil microorganisms in cropland (Davis et a1.…”