Optimisation of harvesting operations

The aim was to determine how the timing of the harvest operation affected crop quality, costs, re-growth potential and sustainability and to identify the extent at which year round supply with minimal storage capacities may be possible via extended harvest windows for each crop.

As an outcome, data on crop quality, financial and sustainability aspects of harvest timing was reported in the following fact-sheet . It was later used in the Supply Chain Integration and Optimization model developed during the project.

A field experiment was established in which a SRC crop was cut at the conventional winter timing and in summer. Parallel experiments were established with Giant Reed, Miscanthus and Sorghum Plots. Evaluation of field losses at different harvest time was carried out in order to provide further data for the soil carbon budget by monitoring harvested plots. In all these crops the nutrient content of the harvested material was measured to quantify losses from the field. The results of the trials are detailed in the following deliverable and summarized below.

As predicted by previously published work early harvesting of bio-energy grasses resulted in greater yields of DM ha-1 and in most cases the greater moisture content could be dealt with by in-field drying. However, elemental composition was much less well suited to thermo-chemical energy conversion technologies, driving the early harvested material to biological conversion technologies to which the composition was better suited. Ultimately the removal of those essential nutritional elements could not be replaced by fertilizer applications leading us to hypothesise that interfering with the senescence process weakened the plants and meant that continuous early harvesting was not sustainable. The effect of later harvesting (post bud burst) on SRC willow was marginal. Some aspects of morphology were changed slightly, but overall yield effects were not recorded.