These rich soils were replenished with mineral nutrients when the adjacent river overflowed its banks during spring floods, and no fertilization was needed to grow vigorous crops.
(These rich soils; were replenished; with mineral nutrients; T:when the adjacent river overflowed its banks during spring floods) (no fertilization; was needed; to grow vigorous crops)
These rich soils no fertilization
were replenished was needed
with mineral nutrients T:when the adjacent river overflowed its banks during spring floods
to grow vigorous crops