Exports are mainly water, carbonacious fiber and common minerals by weight and volume, easily replaced from the atmosphere and dirt without imports needed for replacement. Chemicals are neither imported nor used, do not represent any expense, nor do they require lands devoted to crops to be sold especially to pay for their import. Such insect-repelling herbs are themselves valuable salable crops for culinary, medicinal and crafts uses, and do not represent vacant growing spots nor are they counted as net loss from total productivity. The myth of soil depletion is disproved. The second and third biggest exports in crops are Carbon and Nitrogen, both extracted from the air.
Straw is imported for mushroom cropping.
These ingredients render prior ag-chemical toxicity moot by burying and diluting native soil effectively purifying it. Worms are involved in constantly turning, mixing, blending, and modifying the soil, bringing up toxins for solar and atmospheric breakdown processes. Alfalfa and trees bring up organic trace minerals from 40 foot depth stratas unaffected by decades of ag-pollution and otherwise unavailable to the surface soil ecology in the rootzone. Bacterial digestive acids and humus decomposition acids are constantly mining the inorganic particles for incorporation as increased biota. Intelligence replaces mythology with reality.