This document discusses organic matter in soil and materials that can be used to improve soil quality in gardens. It identifies the main sources of organic matter as the natural decomposition of plant and animal remains, as well as imported materials like farm yard manure and garden compost. Benefits of organic matter include improving soil structure and water and nutrient retention, while limitations include rapid breakdown in well-drained soils and needing regular applications. Specific organic materials discussed are farm yard manure, garden compost, mushroom compost, and municipal compost, comparing the benefits and limitations of each for soil improvement.