**Appendix A**

**Figure A1.** Method used to prepare soil samples for AAS and UV-spectroscopy analysis for plant available concentration.

**Figure A2.** Method used for organic matter (OM) and C analysis of all samples.

**Figure A3.** Method used for Ca, K and Mg analysis of all samples.

**Figure A4.** Methods used for P analysis of all samples.

**Figure A5.** Method used for soil and ash pH analysis.
