Biomass production, foliage and soil nutrient dynamics in organic and inorganic fertilized short rotation willow systems

This dissertation assessed the potential of organic amendments to supplant commercial fertilizer in soil nutrient supply and biomass production of willow crops in Northeastern USA. The application of paper sludge, dairy manure and urea did not have any significant effect on biomass production of Salix x dasyclados (SV1) at two stages at Tully NY. Biosolid compost (BC), digested dairy manure (DM) and urea commercial fertilizer (CF) at a 150 and 200 kg available N ha-1 also did not have any significant effects on biomass production when to Salix miyabeana (SX64) and S. purpurea (9882-34) at three sites: Middlebury VT, Delhi NY and Fredonia NY. However, there were differences in production among the sites with Delhi > Middlebury > Fredonia. Although there were some exceptions at the Tully site, fertilization generally did not influence soil or foliar nutrient concentrations. Organic amendments did increase soil nutrient concentrations at the Delhi and Middlebury sites. Soil nutrient supply and foliar uptake were monitored more closely in SX64 at the Delhi site using PRS probes and stable isotopes technique. Application of BC increased soil P supply rate compared to CT0 and CF treated plots. Soil nutrients supply and foliar uptake varied significantly by season and there was a synchrony between soil nutrient supply and plant uptake. Both soil NO 3- and foliar N concentrations were high in May. This illustrates willows' ability to retain NO3- and reduce leaching in the spring. The addition of BC significantly increased bark delta15N values. Bark N concentration was less than a third of leaf N concentration, and its decline with plant age means that N removal through biomass harvest will not be substantial. The lack of a yield response to fertilization across this range of sites and willow clones affirms that acceptable levels of biomass production can be achieved with no fertilizer additions due to the high internal nutrient cycling. The equal biomass levels and the significant effect of the organic amendments on soil and foliar nutrients makes them a better fertilization options for willow biomass production considering the added environmental and economic benefits associated with land application of organic wastes.;Key words: biomass production, organic amendments, plant nutrient uptake, shrub willow, soil nutrient supply, water use efficiency...