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.

1. RHS Level 2 Certificate Barriers to Learning and Soil Organic Matter

8. Advantages and disadvantages of crop debris etc Recycles waste Soil may then contain very coarse organic matter Low effort – digging in only Turning in weed seeds that will germinate if exposed to light No risk of importing diseases Unlikely to be sufficient on its own Present on site already Disadvantages Advantages

9. Advantages and disadvantages of compost Uncertain nutrient composition. Recycles waste that would otherwise be dumped May contain pests and diseases if not ‘hot’ composted Good source of nutrients Local authority compost may contain plastics, perennial weeds etc Low cost – either free or purchased from LA Disadvantages Advantages

10. Advantages and disadvantages of Farm Yard Manure Can acidify soil; anaerobic decomposition causes foul smell Easily available and inexpensive in bulk Can contain herbicide residues Good for improving drainage Uncertain nutrient composition Good source of nutrients Needs to be stacked and stored Long lasting in the soil Disadvantages Advantages

11. Advantages and disadvantages of spent mushroom compost Can be expensive due to transport costs unless collected. Good organic content and already partially rotted – no need to stack. Alkaline so not good for acid loving plants, fruit etc Alkaline so good for vegetable plots Not readily available in many areas Recycles waste Disadvantages Advantages

12. Advantages and limitations of adding organic matter to the soil Likely to need to import material Improves CEC Can acidify the soil as it decomposes Darkens soil so it warms more quickly Breaks down more quickly in well aerated, well drained soils Encourages formation of ‘crumb’ structure Needs to be regularly applied in bulk – especially intensively cultivated soils Improves drainage and water holding capacity Limitations Advantages