Use of Composted Dairy Manure Solids Mulch for Raspberry: Influences on Soil Nematode Communities and N and P Availability

ABSTRACT.

The effects of mulches of dairy manure solids (DMS) and composted dairy manure solids (CDMS) on soil N and P dynamics, nematode community structure, and root growth were studied over three years in a new field of raspberry planted in northwestern Washington. Five fertilizer/mulch treatments were applied to 16-m-long row plots: (1) 34 kg N ha⁻¹ applied as granular fertilizer in April; (2) 34 kg N ha⁻¹ applied in May; (3) split application of 34 kg N ha⁻¹ April + 34 kg N ha⁻¹ May; (4) 34 kg N ha⁻¹ fertilizer + DMS; and (5) 34 kg N ha⁻¹ fertilizer + CDMS. Cumulative applications of DMS and CDMS were 28 and 49 Mg dry material ha⁻¹ concentrated on the raspberry row, respectively. Adsorption of NO₃-N and P onto anion-exchange resins, and October soil NO₃-N concentrations, were lower in mulched soil than in non-mulched soil, but leaf N concentrations were greater in mulch treatments. Fine root biomass and the abundances of bacterivorous, fungivorous, and omnivorous-predacious nematodes, and the nematode Structure Index were greater in mulched soil than in non-mulched soil. Mulches had no effect on root-lesion nematodes (Pratylenchus penetrans) infecting roots. Our results suggest that mulches of composted or non-composted DMS can enhance root growth, overall soil biological activity, and nutrient acquisition while also reducing soil mineral N pools and the risk of nitrate leaching. There were no substantial differences between composted and non-composted DMS.

ACKNOWLEDGMENT

The authors thank Mike Particka, Washington State University, for field technical assistance.

Additional information

Funding

The authors gratefully acknowledge the Washington Red Raspberry Commission and Agriculture and Agri-Food Canada's Matching Investment Initiative and GAPS programs for funding the research.