The Role Of Compost In Soil

Introducing by

2006-2007

Introduction Composting organic wastes is an environmentally sound means of recycling raw organic materials into valuable soil amendments with many . uses

?Why use compost • •

• • •

Composting is a method of stabilizing organic wastes by the action of microorganism Increasing soil organic matter 30t/ha compost provides ~ 6 t/ha of organic matter = long-term benefits for soil structure, fertility and water holding Slow release nutrients 30 t/ha compost is worth ~ £90/ha Increasing soil microbial population Stabilizing soil pH (fertilizers acidify soil) Better crop establishment & yields

The composting process The basic process is very simple: • Collection of suitably balanced feedstock materials • Shredding • Composting • Maturation • Screening • Application of finished product

Material flow for the conventional .composting process

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?How does composting work

Types of composting (Farmyard manure (FYMPoultry ManureCattle slurryTown refuseSewage sludge-

Characteristics of compost General properties of green waste compost

pH (Electrical conductivity (dS cm-1 (%(Dry matter (Density (kg L-1 (%(Organic matter

8.6 0.773 59 0.5 19

Nutrient contents

Contamination with heavy metals ((mg/kg dry weight

HM loading rates (kg metal/ha/year when compost applied at (35t/ha/yr

Contamination with inert fragments ((% by weight

The effects of compost application Greater diversity of soil organisms Improved soil structure and water retention

Supply of plant nutrients

Suppression of plant pathogens

Effects on soil chemistry • The nitrogen in compost is very stable and is only released slowly – there is therefore little risk of it being leached • Compost is a good source of potassium (in a readily available form( • Compost is a reasonably good source of phosphorous • Trace elements are also retuned to the soil

Copper addition when organic (materials are spread (g/ha/yr

Zinc addition when organic materials (are spread (g/ha/yr

(Organic matter additions (250 kg/ha N

Effect of organic matter inputs on topsoil (available water capacity (AWC

Compost can help conserve soil moisture

Moisture at 10 cm

Effect of organic matter inputs on topsoil -microbial biomass

(Yield (percent of control

An example of the effects on crop yields

Potatoes

Onions

Cabbages

Carrots

Effect of organic matter inputs on topsoil microbial biomass

Effect of total nitrogen inputs on topsoil PMN ((potentially mineralisableN

Effects on soil structure • Organic matter additions improve soil structure on both heavy and light land. • This has beneficial effects on water holding capacity, drainage, erosion and root penetration. • Cultivations are made easier.

Effects on soil biology

• Biological activity is stimulated by the addition of nutrients and by the improvement to soil structure • Some evidence suggests that there can be inhibition of plant diseases

Maximum supply of soil microelements and heavy metals content Element

(United Land (mg/kg

( United Kingdom (Kg/h

Zn

1000

560

Cu

400

280

Ni

100

70

Cd

10

50

Pb

250

1000

Hg

2

2

Cr

-

1000

Maximum limit for soil microelements and heavy metals content due to supply compost ((mg/kg soil Element

Land United

England

European United

Germany

Zn

150

300

300

300

Cu

50

135

140

100

Ni

50

75

75

50

Cd

2

3

3

3

Pb

100

300

300

100

Hg

1

4

4.5

2

Cr

150

-

-

100

Conclusions  Composting can be an effective way of managing organic wastes.  On-farm composting is a useful technique for dealing with farm generated wastes – bringing in material from elsewhere can be a good business in itself.  Application of compost adds to the organic matter in the soil  Compost is a good source of available P and K.  The nitrogen it contains is in a stable state and relatively unavailable in the short term.

References Litterick Audrey, Sinclair Alex ,2006(COMPOST USE IN AGRICULTURE AND FIELD HORTICULTURE (FACTS CPD points (PN/066/067/a( 5 points 1PD 3PN 1E,Sac. Rayns Francis. 2005 ( How does green waste compost affect( center soil fertility ,EIM FAR Researches. Dahama. A., K. (1999( Organic farming for sustainable agriculture. Agro Bolanice, Daryagun, New Delhi 110002. Elgala, A. M; El Damaty, A. Abdel Latif (1976(, Comparative ability of natural humus material and synthetic chelates is extracting Fe, Mn, Zn and Ca from soil. Scitschrift. Pflanzenernahrung W. Boden Kunde helf 3 : 301-307. Henry Doubleday Research Association (1998(, For Organic Excellence HDERA-bublication UK. Schuphan W, (1975(, Yield maximization versus biological value. Qual plant 24 : 281-310.