Preplant Fertilization Increases Substrate Microbial Respiration But Does Not Affect Southern Highbush Blueberry Establishment in a Coconut Coir-based Substrate

Summary

This greenhouse experiment tested whether preplant fertilisation with nutrient solutions could reduce sodium salinity in coconut coir-based substrates and improve southern highbush blueberry establishment. Although preplant fertilisation increased substrate microbial respiration and elevated nutrient concentrations (nitrogen, phosphorus, calcium), it did not reduce sodium levels, increased overall substrate salinity, and failed to improve plant growth metrics (root architecture, leaf area, leaf greenness, biomass) compared to untreated controls.

Regional applicability

The findings are directly applicable to United Kingdom horticultural practice, particularly in container-grown blueberry production systems where coconut coir substrates are increasingly used as peat alternatives. The results suggest UK growers should not rely on preplant fertilisation alone to ameliorate sodium problems in coir-based media, and instead focus on substrate pre-treatment or alternative management strategies.

Key measures

Substrate nitrogen, phosphorus, calcium, sodium and chlorine concentrations; substrate microbial respiration; root architecture; leaf area index; leaf greenness (SPAD); plant biomass accumulation

Outcomes reported

The study measured substrate nutrient and salinity concentrations, microbial respiration rates, and blueberry plant growth parameters (root architecture, leaf area, leaf greenness, biomass) after preplant fertilisation treatments. Preplant fertilisation increased substrate microbial respiration and nutrient concentrations but did not improve blueberry establishment or reduce sodium content.

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