No Nitrogen Fertilizer Needed After We Reduced Compost Applications


One of my goals when I started this channel in 2013 was to share how we provide our plants with all of the nutrients they need using only compost. worm castings, and mulch from free local resources. I was so intent on proving my point, however, that I actually went a little overboard. A soil test this spring showed that 7 of 10 nutrients tested were at high or very high levels, and no nutrients were deficient. In case you’re wondering if this is a problem, very high phosphorus, in particular, contributes to water pollution, inhibits mycorrhizal associations, and can interfere with a plant’s uptake of iron and manganese. The test didn’t measure nitrogen, but I’ll talk more about that in a moment. After seeing the test results, I decided to try to gradually bring down nutrient levels by significantly reducing compost applications, while continuing to use worm castings and mulch. Most of the compost we made last year was not applied to the garden and is still in the bins. And While we typically build 4 or 5 compost piles per year, this year we’ll build only one, which will process fall garden waste. A soil test next spring will show if these reductions are bringing down nutrient levels as intended, or if we need to modify our approach. Now back to the issue of nitrogen. Nitrogen moves through the soil more quickly than phosphorus and potassium, and this transient nature of nitrogen is why most soil tests don’t measure it. So, reductions in compost aimed at reducing phosphorus and potassium will likely reduce nitrogen more quickly. Even so, with the help of nitrogen fixing cover crops, I was never concerned that nitrogen deficiencies would be a problem. Here’s what I said back in mid-April when talking about the impact of using less compost. To compensate for this we’ll plant more nitrogen fixing cover crops, and we’ll observe our plants for signs of nitrogen deficiency. If deficiencies exist, we may have to resort to a nitrogen fertilizer, but I’d bet money that cover crops will be sufficient and no fertilizer will be required. As we now move into the fall, I can say with certainty that there was more than enough nitrogen in the soil for our plants to thrive, and that no additional nitrogen fertilization was needed. Despite cooler temperatures and record rainfall through much of the summer, the garden thrived, and we likely harvested more crops this year than in any prior year. Before closing, I’d like to share what I’ve learned from this experience that I think might be helpful to other organic gardeners: First, compost and mulch from free local resources can significantly reduce or eliminate the need to purchase fertilizers and other soil amendments. I’ve provided a list of free local resources we use in the description below. Second, growing nitrogen fixing cover crops is an inexpensive way to add nitrogen to the soil and provides a number of other benefits that I’ve discussed in prior videos. And third, a soil test every few years can potentially save you time and money by showing you what your soil doesn’t need. In our case, we don’t need to add more nutrients, so we don’t have to work hard to make compost and we don’t have to buy fertilizer. Well, I better get started planting this year’s fall cover crop seeds, which cost less than $5. I’m planting the same mix I planted the last couple years. I’ll provide a link in the description to the mix we’re using in case you’re interested. Well, that’s all for now. Thank you very much for watching, and until next time remember you can change the world one yard at a time.

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