NOCTI 6157 Pennsylvania Applied Horticulture Practice Test

Soil water holding capacity comes from how water is stored in the pore spaces of the soil, and texture sets the baseline for those pores. Beyond texture, soil structure—the way soil particles clump into aggregates and form pore networks—directly shapes how much water can be retained and how easily it drains. Good structure creates a mix of pore sizes: macro-pores that drain freely and micro-pores that hold water for plant use, increasing the amount of water available in the root zone. Too compacted or poorly structured soil has fewer stable aggregates and fewer connected pores, so drainage and water retention are poor, reducing available water. The other factors listed—color, nitrogen content, and pH—affect appearance or chemical properties, not the physical capacity to hold water in the pore spaces.