Beneath our feet lies a bustling ecosystem where earthworms play a vital role in transforming organic matter into nutrient-rich castings known as vermicast. In agricultural, horticultural and market garden operations, vermicast is gaining momentum as a powerful natural fertiliser and soil conditioner. Let’s take a look at how it works.
What is vermicast?
Vermicast, also known as worm castings, worm manure or sometimes "black gold" (due to its high value to the health and growth of plants when mixed into the soil), is an organic material produced through the natural process of vermicomposting. It’s a low cost, eco-biotechnological process of organic waste management that involves the decomposition of organic matter by earthworms.
Worms like to feed on slowly decomposing organic materials such as fruit and vegetable scraps, breaking it down into simpler compounds through their digestive processes. The organic matter is enriched and passed out as a rich humus that can be used in gardens, farms and orchards.
Vermicast used on a kiwifruit orchard
Blair Housley, a kiwifruit orchardist from the Bay of Plenty, has used MyNoke’s vermicast for more than three years. Blair and his team apply the worm castings on new blocks at the time of planting, and just before winter to support photosynthesis and deliver additional nutrition to the roots in the absence of leaves.
“September through to December is our peak growing period, and we like to get the vermicast into the soil as early as possible to enjoy the benefits,” Blair explains.
Vermicast increases aggregation and aeration, which improves drainage and allows plant roots to access water and nutrients easier, which is something Blair has noticed at the orchard.
“When applied from the start on new plantings, water is absorbed by the vermicast and goes straight into the root zone instead of getting washed away,” he says.
The nutrients in vermicast are released slowly, providing a consistent and prolonged supply. This helps maintain a stable nutrient concentration in the soil solution and ensures that plants have access to nutrients when they need them.
Blair works on a basis of 25kg of vermicast per plant, at a planting of 650 plants/Ha. He says that in terms of growth and yield in year 1, his orchard has performed better than others in the same area.
“Some orchardists have put in up to four times more plants, but we have seen better results per plant without that extra investment. The plants grow well and there is also less plant and root disease.”
The characteristics and benefits of vermicast
Vermicast is not like your standard NPK fertilisers. The latter aim to add sufficient levels of major nutrients necessary for crop growth but they ignore physical and biological properties of the soil which are essential for optimising soil functioning and crop production.
MyNoke's vermicast can act like a standard fertiliser, adding some macro nutrients (especially phosphorous) and a wide variety of micronutrients, but their key value lies in soil conditioning. That is, they alter the physical and biological properties of the soil to increase the efficiency of your standard fertilisers and enhance soil functioning on a number of levels:
Microbial activity: Vermicast contains soil microorganisms such as bacteria, fungi, mycorrhiza, protozoa (flagellates, amoebae, ciliates), that aid in soil health and plant growth by converting existing nutrients into plant-available forms - needed for root development, plant growth and increased yields.
Enhanced nutrient availability: Vermicast contains a wide range of macro and micro nutrients, notably phosphorous, which can decrease the amount of typical phosphate fertiliser needed, and calcium, which is essential for plant structure and growth.
pH balanced: Vermicast typically has a neutral to slightly alkaline pH, which helps balance soil acidity levels, creating optimal conditions for plant growth.
Soil structure improvement: It improves soil structure by increasing aeration, water retention, and drainage, creating an improved environment for plant roots and healthier soils.
Enhanced plant growth: Vermicast contains bio stimulators (plant hormones) like cytokinins, gibberellins and auxins such as indole-3-acetic acid (IAA). Gibberellins and auxins boost root growth and activity. This increases nutrient uptake and provides plants with greater access to water in the root zone, often leading to higher yields and healthier plants.
Organic and sustainable: Vermicast is an eco-friendly alternative to chemical fertilisers, supporting sustainable agriculture practices.
Pest and disease resistance: The beneficial microbes in vermicast help strengthen plants' natural defences against pests and diseases, reducing the need for chemical pesticides.
Environmental benefits: Using vermicast reduces the reliance on synthetic fertilisers and minimises pollution associated with production and runoff.
Diagram: How MyNoke vermicast improves soil properties
A balanced and sustainable approach
At ArborGen, a pine tree nursery in the Eastern Bay of Plenty, Franz Behling has used vermicast for 5 years, both on seedlings at sowing season and for cuttings at setting season. He finds using vermicast is economical and beneficial, due to the amount of nutrients it adds to the soil.
“Using natural products builds up the condition of the soil over time and is important to ArborGen, and this includes using natural fertilisers as substitutes for synthetic ones,” he explains.
Manure is also used, but Franz has noticed that mixing vermicast with mulch and manure helps the plants with a steady supply of nutrients.
“Mixing the vermicast with sheep or chicken manure delivers the right pH level. It builds the soil structure over time and assists with plant growth and resilience.” he says.
Vermicast and agricultural performance
In recent years, the impact of vermicast on plant growth has been well documented, and studies on how it impacts on soil and plant health are wide ranging. Many aspects have been researched, including coverage of plant yield, shoot growth, root growth, plant disease suppression, fungal disease suppression and pest suppression.
In the video below, Tokoroa-based organic dairy farmer Ged Goode explains how vermicast has been the base of kickstarting the biological system on his farm.
Improvements to your soil via the addition of vermicast mean you do not need to rely as much on mineral fertilisers. Over time, as vermicast regenerates the soil, plant demand for mineral fertiliser and irrigation water naturally decrease.
To find out more about how you can utilise vermicast as a natural bio stimulant to enhance your soil and boost plant growth, contact the team on info@mynoke.co.nz or call 0800 MYNOKE.