soil fertility, fertilizer, and fertiizization. chapter 5 the om and som
DESCRIPTION
This material is part of my lecturing on soi fertility, fertilizer, and fertilization namely Chapter 6 The OM and SOM written down based on the book of Benjamin Wolf and George H. Snyder. 2002. This material is only for lecture purpose of my class.TRANSCRIPT
Chapter 6. THE ORGANIC MATTER
AND THE SOIL ORGANIC MATTER The place of O.M. to sustain soil productivity
6.1. Introduction: how to understanding?, definition
6.2. The role of SOM in soil productivity
6.3. The classification of SOM
6.4. Organic fertilizer
(For Agro-technology Study Program – FAPERTA UNSOED)
Purwandaru Widyasunu
Soil Sciences Laboratory, Faperta, Unsoed.
2011. Copy in PDF by 2014.
6.1. Introduction, definition
The place of organic matter in providing sustainable
soil, what is mean???
Sustainable agriculture is not possible without sustainable soil. But soil
cannot be sustained without satisfactory SOM, which in turn is largely
dependent on OM additions and how they are handled.
The dependent of sustainable agriculture on organic matter originates
from the many beneficial effect of both OM and SOM forms.
SOM consist of wide variety of plant and
animal tissues in various stages of
decomposition. Various stage: fresh (non-decayed), slightly
decayed, the decayed, and finally forms THE HUMUS.
HUMUS is more stable than the organic
materials from which it is derived.
Humus is transitory in nature and will break
down, albeit very slowly, the rapidity
increasing in soils with ample oxygen and
good moisture levels and at elevated
temperatures.
Both OM and SOM are largely responsible for
soil formation and development.
What is implication of the soil development
on soil productivity???
6.2. The role of SOM in soil productivity
What processes can (we) hope with SOM??? Soil formation and development
The energy derived from the decay supports
the living microorganisms(bacteria, fungi,
actinomycetes). These organisms are constantly
modifying the rocks from which soil is formed, releasing
nutrient for plants.
The more benefit of energy: benefit to larger organisms
(mites, earthworm, and insects) that intimately mix the
fine rock fragments with OM, greatly hastening the
decomposition of the rock and speeding soil formation.
Maintaining large number of diverse of organisms, the OM
helps maintain balance a healthy balance between
beneficial and disease organisms.
The more benefits be hope
By SOM and added OM in soil:
The SOM and new OM supplies energy use for many useful
processes, without which it would become difficult IF NOT
impossible to provide satisfactory production.
Some important processes for agriculture supported by the
energy derived form OM:
1. The decomposition release slowly of nutrient for plant.
2. The SOM provide living N2 fixation microorganism from N
unavailable to N available to plant.
3. The sustenance of mychorrhiza fungi that help keep P in an
available form.
4. The support of bacteria, actinomycetes, and some filamentous
fungi that aid in the formation of cements so essential for
binding individual small soil particles into aggregates or peds.
THE SOM and added OM improves soil physic:
The aggregates formed greatly improved soil
structure and lessen soil bulk density.
The improved soil structure markedly improved crop
production by: 1. Improving water infiltration, thereby lessening soil erosion and
increasing the amount of available water.
2. Increasing air porosity, which allows better movement of air and
water in soils.
3. Providing an ideal environment for beneficial microorganisms and
plants roots.
4. Aiding good tilth, which is necessary for ease in soil preparation as
well as rapid development of seedlings and plants.
5. Reducing erosion by aiding infiltration, and favoring certain soil
characteristic that aid in the movement of suitable amounts of air
and water, WITHOUT which crop production is not possible.
THE OM aids soil productivity in several ways:
1. Increases cation exchange capacity (CEC), allowing
better retention of ammonium-N, K, Ca, and Mg.
2. Provides for chelation of several micro nutrients,
which helps keep them available.
3. Helps keep P available, particularly at both high and
low pH values.
4. Buffers soil, limiting rapid changes in pH or salt
content that can occur with addition of various
chemicals.
5. Decreases dispersion of soil by rain drops or
irrigation and thus lessen surface crust and
compaction.
6. Lessen changes in soil temperatures, which could
interface with nutrient availability and plant survival.
THE EFFECT OF OM AND SOM
thought to:
1. Soil physic
2. Soil chemistry
3. Soil biology
Through:
1. The energy supply produces
2. The carbon and other binding
agent supplies by OM
decomposition
3. The carbon, hormone, nutrient
affect soil biota.
6.3. The classification of SOM
Classification based on OM: size, age, maturity, source
Size: (i) very fine, (ii) fine, (iii) medium, (iv) coarse.
Age: (i) fibric (young), (ii) hemic (medium), (iii) sapric
(old containing humic acid).
Maturity: (i) immature, (ii) slightly mature, (iii)mature.
Can be defined by C/N; C/P; C/S
Source: from vegetation or animal; man made or
natural.
Basic Concept of Organic Matter
OM in soils can exist as:
1. Recently added materials called organic matter
(OM).
2. Decomposed materials beyond recognition, called
soil organic matter (SOM).
Factor affecting OM decomposition: 1. Factor of OM it self: (i) type of material (rich protein, cellulose, lignin,
etc.), (ii) age (young, old), (iii)particle size, (iv) N-content or C/N.
2. Factor out side OM: (i) soil moisture, pH, aeration, temperature,
nutrient content, (ii) weather: sub tropics, tropics, (iii) intensive
agriculture, soil/land/environment degradation.
6.4. Organic fertilizer
What is organic fertilizer:
Fertilizer is making from organic matter
made by human.
Source: plant, animal(fresh or waste).
Process composting aerobic or anaerobic.
The formation of humus-like material
outside the soil.
If composting in soil (by dug the soil) the
materials of animal waste (faeces and urine)
will become night-soil.
Test Range of analysis
C/N 6:1 – 20:1
pH 5-8
Conductivity 0.2 – 2 S/m
Total N 0.5-3.0 %
P 0.1-2.0 %
K
Ca
Mg
S
0.2-1.0 %
0.8-3.5 %
0.3-0.6 %
0.1-2.0 %
Variability of several important composition criteria of compost
(Wolf and Snyder 2002).
The mixing materials:
Need some care for mixing materials in composting to
have desirable product.
Need a balance of wide C/N ratio materials: straw,
stalks, brown leaves, wood chips, those to be mixed
with narrow C/N materials such as manure animal
residues, green leaves, legume hay, biosolids.
Make compost to C/N < 20; if < 12 or less that means
mature compost (ready to be used except of
pathogenic and heavy metals content are forbidden).
Use effective microorganism: LAB (lactic acid
bacteria) and IMO (indigenous microorganism).
The compost amount desire to increase soil
productivity.
Very good soil productivity can be maintained if sufficient OM is added each
year to maintain adequate porosity, allow sufficient water storage and
movement, limit erosion, increase nutrients.
Guatemala soils case: 1 % org-C loss as CO2 equal to 20,000 lb dry
matter/acre. That means 65 % loss of org-C during decomposition process,
leaving only 35 % as SOM. Thus it needs 57,000 lb of OM to be added per
acre to replace the loss 1.0 percent.
Source:
Benjamin Wolf and George H. Snyder. 2002. Sustainable Soils: The Place of Organic
Matter in Sustaining Soils and Their Productivity. The Haworth Press, Inc.