Well theres two ways:
1. Write the results to file as they are generated. (xlswrite & xlsread would be your friends, and you just need to tell them where to write the latest value(s) as needed.) There are better options than xlswrite though.
2. Write the results to a 2-D variable, so, in your inner loop, you would have:
tillage_id(i,j) = s_tillage_id(j)