What positively affects soil structure by increasing water holding capacity in sandy soils?

Organic matter plays a crucial role in improving soil structure, particularly in sandy soils. Sandy soils are generally characterized by their coarse texture and low water retention capabilities. When organic matter, such as compost, well-rotted manure, or leaf litter, is incorporated into these soils, it significantly enhances the soil's ability to retain moisture.

The presence of organic matter increases the aggregation of soil particles, which means that soil particles clump together to form larger particles. This aggregation creates more pore spaces that can hold water, improving the soil's overall structure and its water-holding capacity. Additionally, organic matter encourages beneficial microbial activity, which can further enhance soil fertility and improve drainage and aeration.

In contrast, synthetic fertilizers tend to focus on providing specific nutrients without contributing to soil structure. Pesticides are aimed at controlling pests and diseases and do not have a direct impact on water retention or soil structure. Mulch can help retain surface moisture and reduce erosion but does not directly improve the underlying soil structure as organic matter does.