**4. Conclusions**

From a chemical point of view, almond tree pruning has suitable characteristics for use as a possible source, of biofuel as almond trees present high average gross calorific value with low moisture contents and low concentration of nitrogen.

The proposed hypothesis at the beginning of the trial is confirmed. In our study, the gross calorific value of the samples was more dependent on the varity and on the rootstock than on the C, H, N composition. It will therefore be advisable in the future to find those practices that maximize the yields of this crop both at the level of fruit production and at the level of biomass obtaining.

Among the studied varieties, Marcona presented higher energetical potential than Vayro. Important differences were found between the studied rootstocks. Although GF 305 presented the best results in terms of calorific power, it was also the rootstock with the highest nitrogen content. In contrast, GN had the lowest energy potential but also the lowest nitrogen content.

No significative differences were found in the gross calorific value of the samples according to the fertilization. However, percentage of nitrogen depended highly on the fertilization treatment applied, the saccharides and aminoacid fertilization accumulated a higher level of nitrogen than the humic and fluvic fertilization.

**Author Contributions:** B.V.-M., D.M.S. and I.L.-C. conceived and designed the experiments; A.M.-V. performed the experiments and analyzed the data; B.V.-M., D.M.S. and I.L.-C., A.M.-V. wrote the paper.

**Acknowledgments:** This work was funded by Project 20170734. Development of methods of quantification of riparian vegetation biomass for the managemen<sup>t</sup> of channels of the Comunitat Valenciana. Dirección General de Universidades. Generalitat Valenciana (Spain).

**Conflicts of Interest:** The authors declare no conflict of interest.
