How long would fallout affect cultivated and non-cultivated lands?
It would depend on the abundance and type of radioactive materials in a given area. In the event of nuclear attack, radioactive iodine would be the most critical single factor in the contamination of milk during the first few weeks. After the first 60 days, the principal hazard would arise from strontium 89 and strontium 90. Strontium 89, however, will have virtually disappeared 17 months after its formation. Like other radioactive isotopes of fallout, strontium 90 falls on the surface of plants and can be consumed with foods and forage. Some of it is deposited directly on the soil or washed into it, remaining indefinitely, for all practical purposes, in the top several inches of uncultivated land. Because it is chemically similar to calcium, radioactive strontium would be absorbed by all plants. Plants growing in soils deficient in calcium would absorb more radioactive strontium than those growing in soils abundant in calcium, other conditions being equal.
