How to increase pH

I finally got the results from my soil test. Avg pH in the 4.8 - 5.0 range. We already planted the 11,000 tree saplings on the 10 hectares. With all the canavalia, castor, moringa and the cover crops: pigeon pea and cowpea growing densely after two weeks; it's too late to add any more amendments at this point.

For some of our major fruit tree species on the plantation Im sure this pH is below their preference. My question is what degree of pH buffering can we acheive just from our dense intercropping with green manure?

950m above sea level, and probably 2000mm+ annual rainfall. 5 degrees from the equator.

Biochar would be my recommendation.
Also if the plant are doing okay, dont stress about it. There are natural cultivar of plants that are adapted to your regional soil conditions.