Organic fertilizers aren’t used the same way as synthetics. They are a whole-plant approach instead of a bandage and may require a little more attention (not that much more, don’t worry). However, over time the results can be far superior.
Read on to learn about the differences between organic and synthetic fertilizers and some things to do and not do when using them.
How is Organic Fertilizer Different?
All fertilizers, whether organic or synthetic, are applied with the goal of providing nutrients to the plants. Organic fertilizers are materials derived from plants and living organisms, whether directly, like the rotted down leaves and grass clippings in your compost pile, or secondarily, like manure, bone meal, or fish emulsion.
Since organic fertilizer was once a living thing, it contains the macro and micronutrients present in its parent materials. Check out our blog post for more information about specific organic fertilizer ingredients.
Synthetic fertilizers are factory-created blends of three primary nutrients–nitrogen, phosphorous, and potassium–in varying proportions, plus some inert filler material. While some synthetic fertilizers may contain other nutrients, they often do not and most won’t have the entire range like organic fertilizers.
Mineralization of Nutrients
Plants uptake nutrients in their mineral form. Mineralization is the process of soil organisms doing their thing, decomposing organic residues. For example, protein in decaying plant cells can be broken down by soil bacteria into usable forms of nitrogen. For this reason, organic fertilizers are often considered slow-release, meaning their benefit is realized over time, not instantly like many synthetics.
The mineralization process is why organic fertilizers feed plants over time, and the nutrients are held in the soil instead of being prone to leaching away. Synthetic fertilizers don’t need to be mineralized, and feed plants quickly, but will need frequent reapplications. Slow-release synthetics are treated to reduce the speed at which they dissolve, attempting to replicate the even-feeding process of organics.
Organic Fertilizer Do’s and Don’ts
- Do consider organic fertilizers’ release rate or availability time frame–they are not all the same. While many synthetic fertilizers are immediately available, organic products take time, and it varies. Packaged organic products are easy to use and may be identified on the bag as slow-release or not.
Rapid-growth plants like corn and potatoes benefit from quicker-release products high in nitrogen, like blood meal, fish emulsion, and well-aged manures. Composts, feather meals, and bone meals will release nutrients at a medium rate, and products like leaves and pine needles are slower to decay (and work wonderfully as mulch).
- Do apply enough fertilizer. When you switch from synthetics to organics, you may be surprised at the higher volume of products recommended for application. The higher amount is because organic fertilizers are not concentrated in a factory. As always, follow the directions on the package.
- Do adopt organic fertilizers as a whole-system approach, using integrated pest management and other soil health practices.
- Do use multiple methods and find what works best for you. Some gardeners find that an annual topping with compost is all they need to grow beautiful gardens. Others may need to add organic fertilizer at planting and again every couple of months.
You may enjoy applying foliar solutions while watering your plants, or perhaps you’d rather apply it as a band at the base of the plants and be done for a while. Pick what works for you and the way you like to garden.
Here Are Some Organic Fertilizer Don’ts
- Don’t negate the benefits of using organic fertilizers–improved soil structure, increased water holding capacity, balanced nutrient levels, healthier and more active soil microbial populations–by engaging in harmful practices like heavy tillage or harsh pesticide use.
- Don’t expect instant results. Organic gardening is partially about working with Nature’s processes, not forcing them. Over time, organic practices’ benefits will make your garden look fantastic, but it won’t happen over the weekend. Monitor and adjust as necessary.
- Don’t apply too much. While it is harder to over-apply organics, it can still be done. Excess fertilizer can burn plants or run off and end up in the watershed. Products like compost are fairly benign, but heavy applications of more potent products like blood meal could cause excess nitrogen problems.
- Don’t forget to get a soil test. If you didn’t get one before planting this spring, that’s okay. You can get one done now–it’s not too late. Start by contacting your local county extension office. A soil test will provide insights into specific issues you may have and allow you to tailor the fertilizer application to your particular needs.
For example, a soil test showing adequate phosphorous and potassium but critically low nitrogen levels would benefit more from a high nitrogen product and less from a balanced or general-purpose fertilizer. Over time, slower release of organic material worked into the soil and increased soil microbial activity will balance the nutrient profile.
Using organic fertilizers is an excellent way to start down the organic gardening path (our favorite) and feel good about what you grow and eat. For more organic gardening info, check out some other resources on our blog, like this post on How to Make Fertilizer Tea.