Effect of dairy effluent on the biomass, transpiration, and elemental composition of Salix kinuyanagi Kimura

The land treatment of Dairy Effluent (DE), comprising urine and faeces is common practice, yet can lead to nutrient imbalances in plants and soils. We aimed to determine the growth, transpiration, and elemental composition of Salix kinuyanagi Kimura (Clone No. PN 386) as affected by DE application. DE was applied for 15 weeks to eighteen 122 dm3 lysimeters, either bare or planted with S. kinuyanagi, at N application rates of 0–558 kg ha−1 over three months. DE application increased biomass and transpiration. Chlorosis, possibly caused by excess Cl, appeared in the highest treatment. DE application increased foliar concentrations ofN, P, K, Cl, and the foliar N:S ratio to above 15, a level indicative of S deficiency. Concentrations of essential trace elements were unaffected. Trees receiving the N equivalent of 279 kg ha−1 removed similar amounts of N and K as were applied in the DE. All DE treatments added more Cl than the plants removed. Soil chloride accumulation may be harmful in drier climes. Future work should include a field trial to determine the long-term sustainability of DE application to willows, and the potential use of willows as animal fodder.

► Application of 279 kg ha-1 per year of Dairy Effluent to S. kinuyanagi produced 50% increase in dry matter production.
► Dairy effluent did not significantly affect the balance of animal nutrients in the foliage.
► Chloride accumulation in soil may limit plant growth in arid regions.
► S. kinuyanagi supplemented with DE provide fodder for stock rich in trace elements.