The Potential of Natural Fertilizers

Organic fertilizer improves soil “tilth”—the condition, or health, of the soil. It is less likely to burn the lawn or leach down through the soil and into groundwater. It also provides a larger complement of minerals for plant growth.

However, natural fertilizers provide relatively low amounts of nutrients, as compared to concentrated fertilizers such as 10-10-10, so it will likely take more effort to incorporate them in your garden.

You also have to plan ahead because it takes time for bacteria and fungi to break down organic fertilizers into the nutrients that plants require. And organic fertilizers tend to be more expensive than conventional products.

Once you have your soil tested and bring nutrient levels up to adequate levels, add supplemental nutrients each year to replace the nitrogen, phosphorus, and potassium extracted by fast-growing vegetables.

Organic fertilizers, such as horse, cattle or poultry manure, dried blood, fish emulsion, or cottonseed meal, can replace the nitrogen used by plants if you apply adequate quantities each year. Apply them at planting time so nitrogen will be available to the vegetables during their peak nitrogen demand—from three to ten weeks after seeding.

Most Midwest soils contain some phosphorus. However, the amount may be inadequate to support rapidly growing vegetables. The most common organic sources of phosphorus include steamed bone meal, rock phosphate, and horse, cattle, or poultry manure.

Before carrying large quantities of organic potassium to your garden, have the soil tested. If the potassium level is above 300 pounds per acre, no additional potassium is required. If it is below that, use granite dust, greensand, wood ash, or horse, cattle, or poultry manure as a source of potassium.

No fertilizer will alleviate poor soil-building practices. So, be sure to supply your garden with generous amounts of compost to maintain organic matter in the soil and promote good plant growth.