Answer:
Humus
Manure
Nitrogen
Step-by-step explanation:
Soil fertility is a characteristic of soil that refers to the capability of soil to maintain and provide a suitable habitat for growth of agricultural crops, thus resulting to continuous productivity.
The fertility of soil may be influenced or enhanced by various factors which includes, the soil structure, organic matter, soil pH, and water retention among other factors.
Humus, nitrogen, and manure are among the factors that boosts or improves soil fertility, and thus enhances growth and sustainability of agricultural crops by the soil