Memorandum submitted by Natural Organic
Fertiliser Company Ltd
The response provided below, from Natural Organic
Fertiliser Company Ltd (Nofco), is to ensure that the beneficial
use of organic green and ABP compost is duly noted, and that its
usage should not be restricted in any way under the proposed Nitrates
Directive.
1. INTRODUCTION
TEG Environmental Ltd composts source segregated
municipal solid wastes. The resultant material is stable compost
containing 45.5% organic matter, biomass and plant nutrients for
recycling to agriculture, which is marketed by Nofco. The nitrogen
in the composted materials has been incorporated into the compost
biomass and stable forms of organic matter, which act as a slow
release fertiliser over many years following application.
This document demonstrates the importance
of adding organic matter and nutrients to soils with reference
to EU and UK research and findings and (RB209). Compost is a low
risk product, and should be excluded from any closed periods or
loading limits in the forthcoming Nitrates Directive (England).
2. SOIL ORGANIC
MATTER (SOM)
The primary source of SOM is plants, although
animals, through waste products and the decomposition of their
bodies provide a secondary source. In plant tissue, water makes
up about 75% of the fresh weight of the plant, whilst 25% is composed
of dry matter. In composted material the proportions of these
elements will vary but the same basic components exist as well
as an existing and active biomass. The elemental composition of
the biomass is about 44% carbon, 40% oxygen, 8% hydrogen and 8%
ash which incorporates all the elements listed above. Most of
this is used as the building blocks for carbohydrates (60%), lignins
(25%), proteins (10%), fats, waxes and tannins (5%). Sugars, starches
and simple proteins decompose rapidly, whilst fats, waxes and
lignins decompose very slowly. The decomposition of carbon and
hydrogen containing compounds releases CO2 (carbon dioxide) and
water whilst the decomposition of proteins eventually releases
NH4 (ammonium), NO3 (nitrate) and SO4 (sulphate). Humus, which
is created through a process of synthesis as well as of breakdown,
is also an important product of organic matter decomposition.
As well as producing a certain quantity of nutrients that are
taken up by higher plants, humus is important for a number of
other reasons. The surface area of colloidal humus particles (micelles)
is high. This contributes to its high Cation Exchange Capacity
(CEC), Water Holding Capacity (WHC) and is important in aggregate
formation and stability.
The CEC of micelles may be 2-30 times higher
than for mineral colloids, and this may account for as much as
20-90% of the adsorption of cations by mineral soils. SOM may
help to provide easily replaceable cations on humus colloids,
and increase the availability of Nitrogen (N), Phosphorus (P),
Sulphur (S) and micro-nutrients held in organic forms. Acid humus
may also help to release elements from mineral soils. Soil
Organic Matter also improves the physical properties of the soil
by encouraging granulation, WHC and by reducing plasticity (and
cohesion).
In summary, organic matter positively influences
physical and chemical properties of the soils far out of proportion
to the small quantities present. It commonly accounts for as much
as one third of cation exchange capacity of surface soils and
is responsible, perhaps more than any other single factor, for
the stability of soil aggregates.
2.1 MICROBIAL
BIOMASS CARBON
(C)
A recent study funded using Landfill Tax Credits
into the benefits of applying compost to agriculture was undertaken
by Enviros, with research studies by Rothhamsted and Reading University
(Compost Use in Agriculture Consolidated Report—January
2005), which concluded that:
"However, at the end of the 100 day incubation,
the biomass in the soils given compost was still significantly
larger than in soils where it was not applied".
2.2 SOIL PROTECTION
A recent Information Sheet was also produced
by the Soil Association "Organic farming and the environment"
which reinforced the need to supply soils with organic matter.
An extract from that document is shown below:
Conserving the land
Defra has calculated that up to 2.3 million
tonnes of soil is lost every year in agriculture. With c 6% of
the soil in England and Wales now at high to very high risk of
erosion, and much more land vulnerable to significant off-farm
effects, organic farming is of immense importance to the UK's
soil protection objectives.
Soil protection
Soil erosion is caused by the loss of organic
matter and exposure. The mode of plant nutrition is highly pertinent
here and is completely different in conventional and organic/natural
agricultural systems. In intensive, arable systems, the possibilities
for soil protection are inherently limited since soil organic
matter does not play a major role and because the use of inorganic
fertilisers and pesticides, which replaces the dependency on organic
matter, actually inhibits soil life and thus the development of
a healthy soil structure. In contrast, organic farming developed
out of a realisation of the central role of the soil in natural
plant nutrition and also an early concern over soil erosion. As
in nature, organic farming is therefore based on the use of organic
matter in the soil as the plant's nutrient source, with the nutrients
supplied by the soil life, especially via fungal mycorrhiza, as
opposed to via free mineral N/P/K. As a side effect of this, the
soil life binds the particles, improving soil structure which
means better water retention, better water drainage and also reduced
compaction susceptibility. In other words, excellent soil protection
is part and parcel of organic farming and the main objective of
many of its practices, such as manure composting, crop rotation,
as well as the non use of inorganic agro-chemicals. Additionally,
because of its more extensive nature and the fact that organic
farming encourages mixed sheep and cattle rearing, which is better
for vegetation, organic farming avoids the damaging effects of
over grazing. Research has confirmed the higher levels of soil
life and organic matter and the reduced erosion potential of organic
farms.
2.3 COMPOST STABILITY
AND N RELEASE
The Enviros research project cited in 2.2 above
provided the following conclusions:
"The field research and soil measurements
have shown that soil organic matter and plant available nutrients
can be raised through the addition of compost. Soil pH was shown
to be stabilised and interesting interactions between compost
and applied nitrogen fertilizer were seen. Nitrogen fertilizers
were able to be reduced by approximately 25kg N/ha where compost
was applied without yield loss. In addition, with some crops
including potatoes in some situations, this led to increased yields
possibly as a result of improved nutrient cycling and availability
over the growing season. When compost is applied all other nutrients,
apart from nitrogen, can probably be omitted from the fertilizer
programme.
Crop yields were generally highest when compost was
applied with the full nitrogen fertilizer rate. However, with
potatoes a high rate of compost coupled with a lower rate of nitrogen
fertilizer (compared with standard recommendations) gave the best
yields. These results should encourage farmers to apply compost
immediately before high value, irrigated crops such as potatoes.
Farmers do not use animal manures too soon before potatoes because
of the unpredictable nature of nitrogen release. Compost releases
only a small amount of nitrogen and appears to make applied inorganic
nitrogen more efficiently used by the crop."
In addition to this, it is commonly known that
well rotted farm yard manure (FYM) converts N into very stable
humic compounds and this is what happens in the composting process.
These compounds act like a slow release N fertilizer for crop
uptake and protect the N in soil from nitrate leaching.
The ADAS "Booklet 1—Making better
use of animal manure on arable land" confirms the slow release
characteristics of organic N in "old FYM" or well rotted
FYM. TEG compost has been processed and stored on site to stabilise
and can be considered to be very similar to "old FYM"
in terms of its stability and N release, thereby providing significant
benefits not only to agricultural production, but also reducing
risks of potential nutrient leaching.
3. EXECUTIVE
SUMMARY
Compost is a valuable source of essential plant
nutrients, and holds them in a slow release form, which ensures
that they are not leached into groundwater. They can therefore
be stored on, and applied to, soils all year round, and do not
need to be included in closed period regulations.
The addition of organic matter to the soil also
improves its humus levels and CEC capacity, further reducing potential
nutrient loss (as proven by ADAS ongoing studies).
The percentage of Nitrogen made available to
the growing crop is small, but does allow for reduction in inorganic
N applications in future years. Compost should be allowed to
be applied to the crop at rates to meet crop need from its available
N, rather than total N, which would then reduce the need for
inorganic fertiliser to be applied to the land. An increase in
whole farm nitrogen loading limit should be proposed where compost
is used. Legislation should be amended to make this clear distinction.
Compost should also be permitted to be applied
at an increased loading per year to increase SOM levels, as it
is more cost effective for a grower to apply large volumes of
material in a single year, and then reduce applications in subsequent
years, rather than small volumes over a number of years.
Defra should include a summary detailing the
benefits of compost applications in future farmer/advisor available
publications, as there is now significant long term evidence showing
its benefits to agriculture and the environment as a whole.
January 2008
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