What is the largest micro when the big is 1080? 
CREATE TABLE "irrigation_infrastructure" (
  "department" text,
  "micro_10ha" real,
  "small_100ha" real,
  "medium_500ha" real,
  "big_500ha" real,
  "total" real
);
SELECT MAX("micro_10ha") FROM "irrigation_infrastructure" WHERE "big_500ha"=1080;