CMG GardenNotes #711 - Vegetable Gardens - Soil Management and Fertilization

Sep 27, 2026

Uploaded by Connor

CMG GardenNotes #711 focuses on improving vegetable garden results through soil management and fertilization. It distinguishes soil amendments from fertilizers by describing legal definitions, nutrient contributions, and the role of soil microorganisms. The guide explains how compost and manure can increase organic matter, improve tilth, aeration, drainage, water and nutrient retention, and help mitigate soil compaction. It then covers practical application methods, incorporation depth, salt-related precautions, and nutrient-release considerations for key plant nutrients.

LanguageEnglish

CategoryHealthcare

FormatPDF

Pages8

Reading Time20 min

AccessFree to download

Soil Amendment or Fertilizer

How Organic Amendments Improve the Soil

Application

Precautions When Using Compost and Manure

CMG GardenNotes \#711 Vegetable Gardens: Soil Management and Fertilization Outline: Soil Amendment or Fertilizer, page 1 How Organic Amendments Improve the Soil, page 2 Application, page 2 Precautions When Using Compost and Manure , page 4 Nutrient Release Rates from Compost and Manure , page 4 Fertilization, page 4 Nitrogen Applications, page 4 Starter Fertilizers , page 5 Nitrogen “Side Dressing”, page 6 Phosphorus and Potassium Applications , page 7 Managing Soil Compaction , page 7 In the garden, managing soils to improve tilth and maintain garden fertilization are related but not necessarily the same process. For example, compost or manure may be added as a soil amendment to improve tilth; however, they may only add nominal plant nutrients. A manufactured fertilizer may be added to supplement soil fertility levels, but it will not improve a soil’s tilth. For optimum yields and quality, gardeners need to pay attention to both soil management for improving tilth and soil fertilization. Tilth is a term related to the suitability of a soil to support plant growth. Technically speaking, tilth is the physical condition of soil as related to its ease of tillage, fitness of seedbed, and impedance to seeding emergence and root penetration. Soil Amendment or Fertilizer The term soil amendment refers to any material mixed into a soil. By law, soil amendments make no legal claims about nutrient content or other helpful (or harmful) properties. Compost and manure are common soil amendments used to improve soil tilth. They may also supply nominal amounts of plant nutrients. Some of the nutrient effect seen from adding soil amendments is likely due to their effect on soil microorganisms. The organic material in soil amendments is a food source that allows microorganisms to multiply. The larger numbers increase the conversion of nutrients in the soil to plant usable forms. By contrast, mulch refers to a material placed on the soil surface. By law, the term fertilizer refers to a material that guarantees a minimum percentage of nutrients of nitrogen, phosphate, and potassium. Organic fertilizer is derived from natural sources and guarantees the minimum percentages of nitrogen, phosphate, and potassium. Soil Amendments In the vegetable garden, the routine addition of organic soil amendments such as compost can optimize potential yields and quality. The goal in soil management is to increase the organic content to 3-5%, over a period of years. This level of organic material will produce nitrogen through a process called mineralization over time. However, it does need to be maintained as it will diminish over time, especially in intensive gardening such as vegetable gardening. Common amendments may include compost, manure, compost made with manure, fall leaves, straw, coco (coconut) coir, or peat moss. Home compost has the advantage that the gardener is in control of what goes into the compost, reducing problems with salts, weed seeds, and plant diseases. In climates with long growing seasons, another method to add organic matter is to grow green manure crops in between the vegetable growing season. In some areas, this would be a winter crop, in hot areas of the south this would be a summer heat crop. In areas like Colorado, where the entire growing season is used for vegetable production, a green manure is less practical. For additional information, refer to CMG GardenNotes \#244, Cover Crops and Green Manure Crops. How Organic Amendments Improve the Soil On clayey soil, organic matter (over a period of years) glues the tiny soil particles together into larger aggregates, increasing pore space. This increases soil aeration and improves soil drainage, which in-turn increases plant rooting depth allowing roots to reach a larger supply of water and nutrients. On sandy soils, organic matter holds over ten times more water and nutrients than sand. Organic matter also encourages the beneficial activit

FAQs

What is the difference between a soil amendment and fertilizer?

Soil amendments are materials mixed into soil and, by law, make no legal nutrient-content claims. Fertilizers are materials guaranteed to provide minimum percentages of nitrogen, phosphate, and potassium.

How do organic amendments improve soil tilth and plant growth?

Organic matter helps bind soil particles into aggregates, increases pore space, improves aeration and drainage, and can deepen rooting. It also supports beneficial soil organisms and helps remediate compaction.

What key precautions apply when using compost or manure?

Application depends on salt content and incorporation depth. Compost made with manure or biosolids may have higher salt, so rates may need restriction unless a soil test shows low salt; amendments above 10 dS/m total salt are considered questionable.

Sep 27, 2026

Uploaded by Connor