What
Tree crops for the most part is farmed with synthetic fertilizers. This generate the need for chemical sprays because of pest and disease attacks. Furthermore, herbicides are used widely in orchards to eradicate any competition whatsoever. Soils are bare under trees. Integrated pest and disease management programs becomes essential to be able to comply to international standards. Expensive irrigation systems and chemigator's are installed that can also apply fertilizer and chemicals.
How
It is quite possible to farm Macadamia's trees without any inorganic fertilizers or chemical sprays. Establish a living mulch with a ground cover type plant ( green leaf ex. Desmodium intortum) that is not too high between rows as well is in row areas. Apply some more mulch like wheat straw if available on the rows starting rain season. Let the groundcover overgrown it. Apply 50 to 200ml SBM per tree two times a year in February and September depending on tree age. When groundcover grow too high just slash it down. No need for any synthetic fertilizers.