i don't believe there exists a more simple method than directly to dry it, for estimated general data I can cite you the paper from Friend, D., and R. H. V. Corley. "Measuring coconut palm dry matter production." Experimental Agriculture 30.02 (1994): 223-235.

I don't believe too, It depends on moisture retention capacity of the type of coconut (varies between stages of maturation of the fruit) and climatic conditions of the defined location (sunlight time, rainfall intensity, and etc ..). Is necessary determinate in different stages and months e find a correlation for a specific type of place.

I certainly agree with above two. You would have to take samples, measure the dry content then take an average.

Thanks Muhammad and Carlos. I guess I have no choice but to take samples. Thanks again.

I think the best alternative is the method of kiln drying (103 +-2 degree celsius ) until constant weight.

Dear, sir, have look at this manual.