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Definition
In many countries where people suffer chronic food security
problems, the soils are old and highly weathered; they have
inherently low levels of mineral nutrients and are dominated
by types of clays that don't retain plant nutrients well.
Their Nitrogen content, as well as their capacity for nutrient
retention, is most strongly related to the soil's organic
matter content. But, clearing the soil of its natural vegetation
and bringing it into cultivation results in a rapid decline
in soil organic matter. Continuous cropping without returning
organic matter to the soil, protecting the soil from erosion,
and replenishing the nutrients removed with the harvested
crop rapidly depletes soil fertility and generally causes
the soils to become completely degraded (non-productive) within
a relatively short period of time. It is possible to intensify
agricultural production and maintain the productivity of soils
indefinitely. However, this requires a strategic plan for
replenishing soil organic, as well as making judicious use
of fertilizer inputs to replace the nutrients removed by cropping.
Below, you'll find links to technical information about the
role of soil organic matter in soil fertility maintenance
and the efficient and effective utilization of the following
organic resources: farmyard manure, composts,
crop residues; agroforestry, green
manures, and cover crops.
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Related topics
Background information on soils
Soil health management
Soil conservation (erosion
control, tillage, moisture conservation)
Integrated nutrient management
(INM): Overview
INM: Replenishing soil organic matter
INM: Replenishing mineral nutrients
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Relevant literature
Available in PDF format
 Scientific
references: replenishing soil organic matter
Available on the Internet
General references
Soil organic matter reference book
- Website: FAO
land and water publication series directory
This link takes you to the directory; scroll down to find the link to soil bulletin #80.
- Reference: Bot, A. and J. Benites. 2005. The importance
of soil organic matter: the key to drought resistant soil,
sustained food and production. FAO Soils Bulletin 80. (
Full text: 98 pages; 3191 KB).
- Description: An extremely informative reference book with
chapters on: OM decomposition and the Food web; Natural
factors influencing the amount of organic matter; Practices
that influence the amount of organic matter; Key factors
in sustaining food production; Role of conservation agriculture
in organic matter deposition and carbon sequestration.
Organic matter management extension leaflet (University
of Minnesota)
- Website: Organic
matter management extension leaflet
- Description: This brief booklet gives an overview of most
of the key concepts that are discussed in-depth in the reference
book above but is easier to access if you have a slow or
expensive Internet connection.
Soil humic substances
- Website: Soil
humic substances
- Description: Information and references on all aspects
soil humic substances. More appropriate for scientists and
university-level students.
Farmyard manure, composts,
and crop residues
Improved farmyard manure management for smallholder
farmers
- Website:
Managing manure to sustain smallholder livelihoods in the
East African highlands
- Reference: Lekasi, J.K., J.C. Tanner, S.K. Kimani, and
P.J. Harris, P.J.C. 2001. Managing Manure to Sustain Smallholder
Livelihoods in the East African Highlands.
- Description: This book details the results of a Kenyan
study that evaluated how farmer manure management strategies
affected manure quality (survey of existing mgmt practices
as well as evaluation of management effects through designed
experiments) and how manure quality affected maize crop
productivity. Manure management matters!
On-farm composting
- Website: FAO
corporate document repository
- Reference: Mira, R., R. Roy, and H. Hiraoka. 2003. On-farm
composting methods. Rome, FAO Land and Water Discussion
Paper 2.
- Description: This book covers both the theory and practice
of composting; it includes informative chapters on small-scale,
large-scale, as well as vermi-composting.
Sir Albert Howard's waste products of agriculture
- Website: Holistic
Agriculture Library
- Reference: Use of phosphate rocks for sustainable agriculture,
FAO fertilizer and plant nutrition bulletin.
- Description: Howard, an agricultural scientist, was one
of the earliest and most articulate proponents of the soil
health concept. He is famous for the development of the
Indore composting method and his book, Waste Products of
Agriculture, contains all the details, as well as photos,
of this seminal piece of development work. The book is available
in its entirety through the Soil and Health Library but
the site librarian has to e-mail you the URL due to Australian
copyright laws governing out of print materials. Worthwhile!
Crop residue management
- Website: FAO
corporate document repository
- Reference: FAO. 2001. Mixed Crop-Livestock Farming: a
review of traditional experiences based on literature and
field experiences. Rome, FAO Animal Production and Health
Papers No. 152.
- Description: Chapter 6 contains information about crop
residue management in mixed farming systems, where crop
residues and livestock manures can be effectively combined
for soil fertility management.
Agroforestry, green
manures, and cover crops
Look for additional information on these three topics through
the soil health portal.
Forage tree legumes
- Website: Forage
tree legumes
- Reference: Gutteridge, R.C. And H.M Shelton. 1998. Forage
Tree Legumes in Tropical Agriculture. Tropical Grassland
Society of Australia, Queensland.
- Description: Multi-purpose legumes are more attractive
to farmers than legumes that can only be used for soil improvement.
This link leads to the complete text of a very useful book
on leguminous agroforestry trees whose foliage can also
be used as livestock forage. Improvements in livestock feeds
also results in improvements in manure quality. The book
has lots of specific, very practical information on the
adaptation, management, and pests and disease of many tree
legume species, including Leucaena lucocephala, Gliricidia
sepium, Sesbania spp.,Calliandra calothyrus,
etc.
Agroforestry in Africa
- Website: Agroforestry
in Africa
- Reference: McDonald, L.H. 1981. Agroforestry in the African
Humid Tropics. United Nations University Press, Tokyo.
- Description: Full text conference proceedings. Chapters:
include Principles of Agroforestry, Traditional Agroforestry
Systems, Current agroforestry Activities and Considerations
for the future development of agroforestry.
The Overstory
- Website: The
Overstory
- Description: This is a free online journal focusing on
trees and crops in agroforestry. You can access issues at
the site, as well as register to receive new issues by email.
Biological restoration of a degraded soil
- Website: International
Soil Conservation Organization
Click on "List of Proceedings and Meetings" on
left hand side of page, then choose the 10th proceedings;
scroll through the list of accessible PDF documents. The
Tian article begins on page 333 of the proceedings.
- Reference: Tian, G., F. Salako, and J. Zhang. 1999. Biological
restoration of a degraded Alfisol in the humid tropics using
planted woody fallows: synthesis of 8 years results. Paper
presented at 10th Annual International Soil Conservation
Organization meeting.
- Description: The authors review the results of a multi-year
trial undertaken to compare soil quality changes (biological,
chemical, and physical) under planted fallows to natural
fallows or continuous cultivation. An interesting, more
researcher-oriented article-it also includes citations for
the numerous papers on the trial that the authors published
in peer-reviewed journals.
Legume research network newsletters
- Website: Legume
research network newsletters
- Description: These newsletters highlight the research
and extension activities of the Legume Research Network,
a group of multi-institutional researchers and extensionists
who have been devoted to increasing the use of soil-improving
legumes in smallholder Kenyan agriculture since 1995.
Mucuna news from CIEPCA
- Website: CIEPCA
- Description: Mucuna is a leguminous cover crop with tremendous
potential for improving soil fertility. It is adapted to
a broad range of environments(0 - 1900 masl), produces a
lot of nitrogen-rich biomass, and effectively smothers weed.
Unfortunately, the seeds and foliage contain toxins that
have limited mucuna's utilization as a food or feed crop.
Mucuna News documents various research that has aimed at
improving mucuna's potential as a multipurpose legume.
Technical Bulletins from CIDICCO
- Website: CIDICCO
- Description: CIDICCO is a Honduran organization that documents
legume use in traditional farming systems in Central America.
Online
versions of some of their technical reports, as
well as bulletins/newletters, or are available, including
ones on velvetbean (Mucuna pruriens), fava/broad
beans (Vicia faba), Lima beans (Phaseolus lunatus).
Others are available for purchase.
Cover crops for tropical highlands
- Website: Cover
crops for tropical highlands
- Description: A learning module that links users to information
about cover crop species that are adapted to the tropical
highlands (> 2000 m above sea level), including characteristics
of the crops, seed suppliers, discussion groups, and further
references.
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Relevant links
FORMAT (Forum for Organic Resource Management and Agricultural
Technologies)
- Website: FORMAT
- Description: The website for An Africa-based NGO whose mission
is to "Develop a forum for common understanding, interaction
and networking in natural and organic resource management,
agricultural development and policy advocacy through knowledge
sharing amongst development and research institutions, individuals
and the private sector.
World Agroforestry Centre
- Website: World Agroforestry Centre
- Description: Formerly known as the International Council for
Research on Agroforestry (ICRAF), their mission is to advance
the science and practice of agroforestry.
Tropical Soil Biology and Fertility Institute of CIATM
- Website: CIAT
- Description "The Tropical Soil Biology and Fertility
Programme (TSBF) was founded in 1984 to develop capacity
for soil biology as a research discipline in the tropical
regions, and to conduct research on the role of soil biology
in maintaining or improving soil fertility and combating
environmental degradation, on the premise that biological
management of soil fertility is an essential component of
sustainable agricultural development…. In December
2001, an agreement between CIAT and the TSBF Programme led
to the latter's becoming an institute of CIAT (TSBF-CIAT).
Today, the Institute operates as an integral part of the
CIAT research programme."
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