Organic fertilisers are derived from biological sources, such as manure or plant matter. They provide nutrients to soils and plants much like synthetic fertilisers, however, these are usually slower acting. Composts can be seen as an organic fertiliser. Both compost and organic fertilisers can be seen as more environmentally friendly than synthetic fertilisers, however, this is dependant on the type of fertiliser used.
Derived from coconut husks, coir is added to the soil to help encourage growth. It is rich in potassium and its pH is fairly balanced.
- Coir is a by product, coconut fruit and milk is taken away and the husk is waste.(ref) This takes a waste product and uses it. Despite this, coconuts are grown in hotter climates, such as that found in Sri Lanka and Mexico (ref) meaning the product will have to travel a fair distance to be used in the UK, adding to its carbon footprint as CO2 will most likely be emitted to transport the material.
- Coir helps soil retain water, (ref) reducing water use and wastage.
- Coir also creates aeration in the soil, stopping it from compacting. (ref)
Seaweed is a natural plant that grows in abundance in the sea. It has been used and collected in the UK since Roman times, and is used worldwide for food, soap, fertiliser etc. It can be a great source of nutrients for plants, but there are some things to consider when purchasing/ harvesting it:
- Production of seaweed has soared in recent years, going from 13.5 million tonnes in 1995 to just over 30 million tonnes in 2016. (ref)
- Hand picking seaweed is the most common form of harvesting, however, mechanical harvesting using a comb is also possible. (ref)
- The UK harvests around 2000-3000 dry tonnes of seaweed every year, (ref) but with growing global demand, there is more interest in the UK's seaweed, especially in Scotland. (ref) Companies have petitioned to harvest 0.15% of kelp in Scottish waters, around 34,000 tonnes. Sustainable measures where also taken into account, by leaving younger plants alone from the combs that harvest and giving areas time to recover from harvesting. However, there is not a lot of data about UK seaweed and harvesting it sustainably. (ref) This data is being created and collected now, as commercial seaweed harvesting is being tested in the UK. (ref), (ref)
- There are concerns about the harvesting of seaweed, however, as the machines remove entire plants, restricting the ability of a kelp forest to recover. There are also issues about the fact that removing seaweed can send ripples down the food chain. (ref) It may, therefore, impact biodiversity and genetic diversity. (ref)
- Seaweed also helps the sea act as a carbon sink. (ref) If more seaweed is grown for commercial purpose, this could help combat climate change, however, if it is harvested unsustainably, it could have the opposite effect. Seaweed also absorbs excess nutrients from agriculture that spills into the oceans and reduces it impact, whilst maintaining the seas acidity. However, it is unclear how extensive harvesting and seaweed agriculture will affect this. (ref)
- It is possible to collect seaweed yourself, however only harvest seaweed that has washed up on shore and harvest from multiple places, not just one area. Due to the salt content, do not place in the soil. However, placing the seaweed on top of the soil should be fine and the excess salt will run off. Seaweed can also be composed. (ref)
Manure is derived from animal dung, and can be used from a variety of animals for nurturing the soil. It has been used as a fertiliser for centuries. Here are some things to consider with manure.
- The nutrients in manure enrich the soil, but it also conditions the soil, improving its quality and helping retain moisture. (ref) This reduces the need to use as much water as the soil will retain water much longer.
- Manure does need to be mixed with compost, however, as the large amount of nutrients can 'burn' a plant is directly added. Allowing the manure to decay for a while also works. (ref)
- Manure helps to reduce soil erosion. (ref)
- By using manure, a waste product is taken and repurposed. It also has further environmental benefits reducing the need for mined or manufactured chemicals. (ref)
- It is possible to buy manure from a farm or a stable, meaning the distance travels can be reduced if purchased locally.
- Never use human feces. (ref)
Once used on a large scale, and even exported from the UK, bone meal is not used to the degree it once was, but can still provide nutrients to soil. Here are some things to consider:
- Bone meal is made from ground animal bones, and can be sourced as a byproduct of the meat industry. (ref) Whilst this reduces the waste from the meat industry, it does not stop the environmental impact of the meat industry. (ref)
- Cow bones are usually used in the creation. (ref)
- The bones are cleaned and heated before use. (ref) This adds to the products carbon footprint as energy will be needed to do this and CO2 will most likely be emitted from the energy source.
- Bone meal is a great source of phosphorus, calcium and nitrogen. (ref)
- Being organic, the bone meal helps promote micro organisms in the soil, improving soil fertility. (ref)
Once used to grow mushrooms, this compost is left over, and sold as a byproduct of the mushroom industry. (ref) Due to this, a waste product is recycled which is beneficial for the environment as it reduces the need of other fertilisers/ composts. It is relatively cheap to buy and can be bought in bulk, however, it is usually alkaline, and is not compatible with acidic plants. (ref) Its high salt content may also be problematic for some plants, but it increases the water retention in soil, (ref) which reduces the amount of water needed to water plants etc. as water will not escape as runoff as easily.
A common household waste item, these shells can be used to decompose in soil, providing nutrients, notably calcium, to the soil. The shells alone cannot provide all the nutrients alone, but do have some benefit for plants. (ref) It also reduces the need for other forms of fertiliser, like synthetic chemicals or lime. As the shells take months to decompose, the egg shells should be applied to the soil in Winter, to allow them to decompose in tie for Summer. (ref)
Used Coffee Grounds
Composting coffee grounds provides a source of nitrogen to plants, and is slow acting in its nutrient release. The grounds will also attract wildlife, such as earthworms. (ref) In reusing the coffee grounds, a waste product is given another purpose and stops it going into a landfill. However, coffee grounds are high in caffeine. In plants, caffeine acts to restrict growth, which can be problematic if the grounds are used to promote growth. (ref)