Soil Nutrient Availability in Traditional Dig Versus No Dig Gardening
The Level Of Soil Nutrient Availability In Traditional Dig Versus No Dig Gardening Is Significant & Accounts For The Annual Increase In Yields In The No Dig System. This Is Largely Due To The Methods Of Application, Decomposition Processes & Soil Interactions.
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Compost adds a wide range of essential plant nutrients
Many gardeners believe farmyard manure (FYM) and compost are the same. But they aren’t. FYM decomposition levels vary greatly from “raw” to well decomposed and I have seen many FYM heaps that are claimed to be well rotted but still have visible straw or bedding in them that haw not undergone any level of decomposition. This leads to significant variations within traditional methods and between them and No Dig. Soil nutrient levels can vary significantly.
Here’s a comparison and contrast of nutrient availability in the two systems:
Nutrient Release Timing
Traditional Dig-In Farmyard Manure (FYM):
Nutrients in FYM are released more slowly because the organic matter is incorporated into the soil, where microbial decomposition occurs gradually.
The digging process can accelerate initial breakdown by exposing the manure to soil microbes and oxygen, but the overall release of nutrients (especially nitrogen) is slower and more prolonged.
Nutrients like nitrogen may be temporarily immobilised by soil microbes as they break down the carbon-rich material.
Compost in No-Dig Systems:
Compost is significantly decomposed, so nutrients are more readily available to plants compared to raw FYM.
In no-dig systems, compost is applied as a surface mulch, which releases nutrients steadily as it interacts with soil microbes and moisture.
The nutrient release is more consistent and less prone to leaching, as the compost breaks down gradually on the soil surface. A single layer of compost can last a whole season.
Nutrient Accessibility
Traditional Dig-In FYM:
Nutrients are mixed into the soil, making them more accessible to plant roots over time.
However, digging can disrupt soil structure and microbial communities, potentially reducing the efficiency of nutrient cycling.
Compost in No-Dig Systems:
Nutrients are concentrated near the soil surface, which can be beneficial for shallow-rooted plants.
The no-dig approach preserves soil structure and microbial activity, enhancing nutrient cycling and long-term soil health.
Over time, nutrients from the compost migrate downward into the soil profile, benefiting deeper-rooted plants. This is how it happens in nature.
Soil Health and Microbial Activity
Traditional Dig-In FYM:
Digging can disturb soil ecosystems, reducing the population of beneficial microbes and fungi that aid in nutrient cycling.
The incorporation of FYM can improve soil fertility over time but may lead to uneven nutrient distribution and temporary nutrient tie-up.
Compost in No-Dig Systems:
No-dig systems promote a thriving soil microbiome, as the soil structure remains intact and undisturbed. This resembles what happens in woodland in the leaf litter layer which is topped up each autumn. Ditto under hedges where soil carbon levels are much higher than in open fields.
Compost acts as a food source for soil microbes, enhancing their activity and improving nutrient availability through natural decomposition processes.
Risk of Nutrient Loss
Traditional Dig-In FYM:
Nutrients, especially nitrogen, are more prone to leaching or volatilisation when FYM is dug into the soil, particularly in wet or poorly drained conditions. Think how this impacts levels in allotments and gardens prone to water logging or flooding.
Digging can also expose organic matter to rapid decomposition, leading to short-term nutrient surges followed by depletion.
Compost in No-Dig Systems:
Compost applied as mulch reduces the risk of nutrient leaching, as the nutrients are released slowly and are better retained in the soil.
The protective layer of compost also helps conserve soil moisture, further enhancing nutrient availability.
Long-Term Soil Fertility
Traditional Dig-In FYM:
Improves soil fertility over time but may require repeated applications and digging, which can degrade soil structure and lead to compaction. Rotavators are prone to cause subsoil surface panning or soil smearing which is detrimental to soil structure.
The benefits depend on the quality of the FYM and the frequency of application.
Compost in No-Dig Systems:
Builds long-term soil fertility by improving organic matter content, soil structure, and microbial diversity.
The no-dig approach minimises soil disturbance, allowing for sustainable nutrient cycling and improved soil health over time.
Soil Nutrient Availability Summary
Traditional Dig-In FYM: Provides a slower, more variable release of nutrients, with a higher risk of nutrient loss and soil disturbance. It is effective for improving soil fertility very but requires careful management.
Compost in No-Dig Systems: Offers more consistent nutrient availability, preserves soil structure, and enhances microbial activity. It is a sustainable approach that builds long-term soil health and reduces nutrient loss.
Both methods have their merits, but compost in no-dig systems is generally more efficient and sustainable for maintaining nutrient availability and soil health.
The Research on Soil Nutrient Availability In Traditional and No Dig Systems
I’m very conscious of how wedded we can become to specific ideas and techniques. Hence I might well be accused of bias in my article. That is a fair observation, however, I was a traditional market gardener for many years before embracing No Dig. I have studied the science behind it and have spoken to experts in both techniques. I have also read reams of research on both, some of it going back centuries. The above is therefore evidence based and not a personal bias. I am of course willing to consider other verifiable and replicable evidence. Some of the evidence I reviewed is summarised below.
Here are some verifiable research studies and sources that support the comparison between traditional dig-in farmyard manure (FYM) and compost in no-dig systems, particularly regarding nutrient availability, soil health, and long-term fertility:
1. Nutrient Release Timing and Availability
Study: “Composting and compost utilization in agricultural systems” (Rynk et al., 1992)
Findings: Compost is more stable and releases nutrients more gradually compared to raw manure, which undergoes rapid decomposition when incorporated into the soil. This study highlights that compost provides a more consistent nutrient supply, reducing the risk of nutrient leaching.
Study: “Nitrogen dynamics in soils amended with composted and uncomposted manure” (Eghball et al., 1997)
Findings: Composted manure releases nitrogen more slowly than raw manure, reducing the risk of nitrogen loss through leaching or volatilisation. This supports the idea that compost in no-dig systems provides more stable nutrient availability.
Study: “No-till farming and soil organic matter: Key to soil carbon sequestration” (Lal et al., 2007)
Findings: No-till (no-dig) systems improve soil organic matter and microbial activity compared to conventional tillage. This study emphasizes that reduced soil disturbance enhances nutrient cycling and soil health.
Study: “The role of compost in improving soil properties and sustaining soil fertility” (Diacono & Montemurro, 2010)
Findings: Compost application improves soil structure, microbial activity, and nutrient availability over time. The study highlights the benefits of compost in no-dig systems for long-term soil fertility.
Source: Diacono & Montemurro, 2010
3. Risk of Nutrient Loss
Study: “Nitrogen losses from manure and fertilizer applications” (Jarvis et al., 1996)
Findings: Incorporating raw manure into the soil increases the risk of nitrogen loss through leaching and volatilisation. In contrast, surface-applied compost reduces these losses by releasing nutrients slowly.
Study: “Compost as a soil amendment to reduce nutrient leaching” (Tester et al., 1982)
Findings: Compost applied as a surface mulch reduces nutrient leaching compared to incorporated manure, as it releases nutrients gradually and improves soil water retention.
Source: Tester et al., 1982
4. Long-Term Soil Fertility
Study: “Long-term effects of compost and manure on soil quality and productivity” (Edmeades, 2003)
Findings: Long-term application of compost improves soil organic matter, nutrient availability, and crop yields more effectively than raw manure. The study supports the use of compost in no-dig systems for sustainable soil fertility.
Study: “No-till agriculture and soil carbon sequestration” (West & Post, 2002)
Findings: No-till systems increase soil carbon sequestration and improve soil structure, leading to better nutrient retention and long-term fertility. This aligns with the benefits of compost in no-dig systems.
5. Comparison of FYM and Compost in No-Dig Systems
Study: “Comparison of organic amendments: Effects on soil properties and crop yields” (Gaskell et al., 2000)
Findings: Compost outperforms raw manure in improving soil health and nutrient availability, particularly in no-till systems. The study highlights the benefits of compost for sustainable agriculture.
