Hey all. I am interested in promoting the health and sustainability of my garden, I would like to understand the differences between organic and synthetic fertilisers. Can you provide me with detailed information on the benefits of using organic fertiliser compared to synthetic fertiliser, including how it impacts plant growth, soil health, and the environment? I would also appreciate information on any potential drawbacks or limitations to using organic fertiliser and how it compares in terms of cost, application, and availability.
I think your best bet is to hear different opinions from a variety of sources. I will start. Organic fertilizers are less likely to be filled with toxins. They also act more slowly, like nature, so they are less likely to make your plant grow so fast as to attract pests. They are also less likely to kill the overwhelmingly positive microbes in the soil that help your plant and allow it to access the good stuff in the soil that help them grow. You are way less likely to pollute ground water, create dead zones downstream, kill off beneficial insects, and poison your family and community. The plant will likely benefit from them for a longer time, and your plant is likely to make more nutritious food, if it's a food plant.
I'm still trying to soak up all the science/information around organic growing myself.
My experience comes from working as a chef and working with lots of mass produced mono culture type farm produce over the years.
One of the chefs I worked with when starting out used to complain about how things didn't taste as good from when he was younger and I used to think it was hearsay so to speak but there seems to be more and more evidence that fruit and veg grown today has less flavour/nutrients compared to decades ago due to soil depletion and agricultural processes that increase crop yields but disturb soil health (such as irrigation, fertilisation, and harvesting methods that also disrupt the interactions between plants and soil fungi, which reduces absorption of nutrients from the soil.
So for me, I have always been of the school of thought that there is a vast community in the garden of microorganisms and beneficial bacteria/nematodes/critters that all work together; as soon as we start spraying anything unnatural we create the potential to kill some things and possibly feed others creating an unstable environment. The moment we have an unstable environment for one grow season the gap(s) created will be exasperated for the next season, requiring more unnatural sprays and further first-hand mitigation and devaluing the health of the final fruits we are trying to so valuably grow. A healthy biome creates a healthy plant with a strong immune system and full-flavorful calories.
I'm a bit biased obviously, but I think it's best to stick to mulching, compost, compost teas/concoctions and other natural approaches and remedies. I feel like spraying, even at times "organic fertilizers", is no more valuable than adding oil to a car that has an oil leak rather than fixing the leak.
What kind of fertilizers are you considering?
~~~~~~~~~~~~~~What are you going to do now?~~~~~~~~~~~~~~~
"Goin straight Bob. I don’t know, get a job, find myself a gal.. or, I dunno what people do nowadays, build-a, uh, a barn maybe, paint the barn with the gal, put the gal in the barn, you know; American dream."
Mostly I can't stand the idea of paying for something that is limited when I can make as much free organic fertilizer as I want. Also, if I compost, I don't have to pay the city to take away so much trash. So I'm practically making money by making my own organic fertilizer.
Personally, regarding fertilizers, I do not buy into the simplistic equation of evil vs. good. It does not sync with my experience as a grower of food.
The first principle, as I see it, is building a great depth of fertile soil. That is not easy in many locations; it is a quest of epic proportions. And following that, with a great depth of fertility established, a small amount of fertilizer is not out of line.
A practical example at my place: we grow magnificent tomatoes in half barrels, in a fine microclimate, and supply half the neighbourhood with top quality fresh produce. The half barrels are extensively amended every year, with the best compost I can produce, but it's not enough. They are such heavy feeders! So, to augment plant health in our very short growing season, a little bit of slow release commercial fertilizer is worked into the soil.
This is a far cry from iceberg lettuce/fake tomatoes grown in essentially hydroponic chemical conditions and shipped 1500 miles. I think it is wise to keep some perspective on, say, apples vs. oranges, in this debate.
The way I see it is this: Synthetic fertilizers feed the crops, while organic fertilizers feed the soil. To elaborate:
Chemically, "organic" means carbon-based compounds. "Organic farming" has a different and more complicated (and USDA-regulated) meaning, but ultimately this is the difference between synthetic and organic fertilizers. Synthetic nitrogen fertilizers, for example, contain some combination of ammonium (NH4+) and nitrate (NO3-), which are chemically inorganic. Organic nitrogen fertilizers are largely protein / amino acids, which are carbon-based molecules containing a high amount of nitrogen, and are chemically organic. Since carbon is able to form four chemical bonds, organic molecules can be very large and complex.
The important differences between the two types of fertilzer are that the inorganic molecules are more soluble in water and are more easily taken up by plants. While this would seem to be a good thing for the plants, examining the pathway of the two types of molecules from fertilizer to plant reveals a counterintuitive effect:
Synthetic fertilizer quickly dissolves into the water in the soil, creating a large pool of nutrients that can be easily taken up by plants. The crops therefore receive a large pulse of nutrients, stimulating fast photosynthesis and growth. This growth occurs faster than the plants can produce secondary metabolites, compounds which protect the plant from pests and improve the taste of the produce. This makes the crops vulnerable to pests (as noted by John) and less tasteful/nutritious (as noted by Paul). The crops, having their nutrient needs met with compounds that they can absorb directly, reduce their reliance on symbiotic soil microbes. This harms the crops' long-term nutrient uptake ability and disease resistance. The crops are also unable to take up all of the fertilizer dumped on them at once, and the rest is left in solution which is easily leached away, reducing the efficiency of the fertilizer and causing problems (eutrophication) for nearby aquatic ecosystems.
Organic fertilizer is less soluble and less easily taken up by plants. Plants can't generally absorb organic fertilizer directly through their roots, because the molecules are too large/complex. Therefore, they rely on soil microbes to break down the organic molecules into inorganic forms (a process called mineralizing). To aid this process, plants excrete carbon from their roots to "feed" the soil microbes. The soil microbes incorporate the nutrients into their cells, where they are resistant to leaching. The nutrients pass from the microbes into the soil as the microbes die and then back into microbes, meaning there is a small but steady pool of plant-available nutrients in the soil, while the rest is stored away. Mycorrhizal fungi can also pass organic nutrients directly to plants, which increases secondary metabolites. Overall, the plants are healthier because of slow, steady growth and associations with soil microbes.
Note that while this picture is pretty well supported by research, reality is much more nuanced. In general though, I believe organic fertilizers are better for long-term soil health, crop production, and the surrounding environment.
I'm a little surprised no one has mentioned this: chemical fertilizers are all salts. That has lots to do with how easily they dissolve in water - and wash away. They're largely harmful to soil life and create a situation where the soil ecology can't support plants well and you're on the fertilizer treadmill.
Organic fertilizers, in the sense of commercial products sold in that category, may or may not be any better :( There are plenty of organic category farms working with dead soil.
The goal needs to be a thriving, bountiful soil ecosystem that provides for the needs of the plants. Fertilizers as a concept aren't part of that goal. You want to build fertility, which is a different thing than adding fertilizers.
While we still use a little slow-release fertilizer in the tomato barrels, I have been playing with a crude anaerobic compost tea in other parts of the garden with some success.
It would be worth experimenting on a barrel with a cheapo small tomato just to see if I can refine the process. I'm always interested in having a Plan B as a hedge against supply chain breakdowns and inflation.