EXTRACTS FROM
ENABLE 12
NEWSLETTER
OF THE ASSOCIATION
FOR
BETTER LAND HUSBANDRY
EDITORIAL
WATER
Alongside
our house runs a winter stream – the Winterbourne – which is dry in
summer but a
swift torrent during ‘February fill-dyke’, as old lore has it. But this year it started in November, as
the
heavy rainfall rapidly saturated the chalk downs to the north of us,
creating a
growing base-flow that we watched with some trepidation.
Commentators on the floods all over
·
We
were keenly exposed to the dynamics of the inter-related movements of
groundwater and streamflow, which were
clearly
evident as we watched the flood rise - and then fall again some days
later. Seldom before have we taken
such
a frequent and intense interest in the changes of the relative levels
of streamflow and groundwater, to the
extent of measuring
their rises or falls even in
millimetres. At the
same
time we could detect the rapid effects on streamflow
of short intense storms further up the catchment,
superimposed on the more regular base-flow.
Our equipment included no more than eyes, gumboots and an office
ruler,
but we learnt a lot of hydrology at first-hand!
·
Farmers
have been blamed for some of the flooding, but we should remember that
some
economic aspects of agricultural policies have forced a reduction of
the number
of people working the land and pressured farmers into substituting them
by
heavy machinery, whose compactive effects
on the soil
can destroy much of the soil’s porous architecture and provoke ever
more severe
and more widespread runoff (and erosion) than we have seen before now
in
UK. Couple that with the occurrence
of
uncommonly-severe rainstorms of tropical intensities and
rainfall-depths, and
more-frequent serious floods are almost inevitable.
Would a return to farming practices which
favour the maintenance of the soil’s porosity be able significantly to
mitigate
comparable floods
in at least some areas in the future? I
suspect so. We know it can in large
areas of several countries - in
.oOo.
“We now
have the technical capability to build enduring national and global
nutrition
security systems based on sound principles where the short- and
long-term goals
of development are in harmony with each other.
What we often lack is the requisite blend of political will,
professional skill, and farmers’ participation.
We live in this world as guests of green
plants and of the farmers who cultivate them.
If farmers are helped to produce more, agriculture will not go
wrong. If agriculture goes right,
everything else will have a chance for success” .
“Without
regular and
dependable supplies of food, other agricultural products and water, our
whole
economic structure will collapse, and no amount of accounting,
book-keeping,
reckoning, buying or selling will sustain it”.
Cormack and Whitelaw, in: ‘Conservation for
Teachers”, 1957.
WATERSHED DEVELOPMENT - OR SHOULD IT BE
WATERSHED MANAGEMENT?
Batchelor
C1 , Rama
Mohan
Rao2, M.; Mukherjee K3.
(reproduced
with permission)
The Karnataka Watershed
Development Project (KAWAD) is
located in the northern districts of
In
Physical
Characteristics of the Watersheds
Two of the project
watersheds, namely Chinnahagari and Upparahalla, are
located in a predominantly red soil (alfisol)
area
that is underlain by granites and gneisses.
The other watershed, Doddahalla, is
located in
a black soil (vertisol) area that is
underlain by
In all three watersheds,
there has been
a dramatic increase in groundwater extraction for irrigation during the
last
ten years. This has been driven by the
relatively higher profitability of irrigated agriculture when compared
to rainfed agriculture, grants or cheap loans for well
construction and government policies such as free electricity for
pumping
groundwater. Although there may be some
small areas of unexploited aquifer in Chinnahagari
and Upparahalla, all the evidence points
to the
conclusion that current levels of groundwater extraction are
approximate to
annual recharge. Over large areas, wells
are pumped for irrigation each year until they fail.
As a direct consequence of
increased
groundwater extraction, groundwater levels have fallen and, in Chinnahagari and Upparahalla,
shallow wells have failed as borewells
have been
constructed and as extraction from the deep aquifer has become the norm. Falling groundwater levels have led to
changes in the surface hydrology of the project watersheds. Springs and seepage zones have dried and now
only flow or become saturated after exceptionally wet periods. Flow in ephemeral streams is less prolonged
after large rainfall events and, as a consequence, flows into tanks are
reduced. Even though local perception is
that cutting down trees is the main cause of the reduction in tank
inflows, it
is clearly falling groundwater levels that have had the greatest impact
along
with, in some areas, the unregulated construction of check dams and
diversion
weirs in the tank catchment areas.
In the project area, river
gauging data
show that annual surface runoff at the large watershed scale is
somewhat lower
than is often reported or than accepted wisdom would suggest. Although there is large inter-annual
variation, average runoff as a percentage of rainfall is around 6% and
2% for the
Doddahalla and
Doddahalla’s annual groundwater
recharge and, hence,
availability is estimated to be 21% of annual average rainfall. It appears that one positive consequence of
groundwater depletion in this watershed has been an increase in
groundwater
recharge. This is because groundwater
levels no longer approach the ground surface at the end of the rainy
season
and, therefore, rainfall infiltration is not rejected due to lack of
available
storage. Average recharge estimates for Upparahalla and Chinnahagari
are
around 6% and 8% of annual rainfall.
Estimates of groundwater use on a village-by-village basis,
show that extraction is far from uniform.
Levels of groundwater extraction in some villages are more than
2.5
times higher than average recharge values.
Although there is certain to be some real variability in
recharge, in
many cases, this situation is only sustainable if water is flowing into
these
village areas from neighbouring areas. This finding has important implications for
the implementation of the project. If the
project promotes soil and water conservation activities that reduce
these
flows, there will be winners in one village but only at the expense of
losers
in another.
Current extraction of
groundwater for
domestic and livestock purposes is estimated at around 3%, 10% and 12%
of
average annual recharge in Dodda Halla,
Uppara Halla
and Chinna Hagari
respectively. By 2030 these figures
are likely to double
and, for future demands to be met, there
will have to
be a reduction in groundwater use for irrigation at least in the areas
around
villages. In some villages, there are
already problems of water shortage in the summer season.
In these cases, it is the poor, particularly
women and children, who suffer the most.
Even more worrying is the prospect of a major groundwater
drought in the
region. Levels of groundwater extraction
are such that, in many areas, there is no longer a groundwater “buffer”
that
can be used as a source of supply during periods of meteorological
drought when
no recharge will take place.
Conclusions
Specific to the KAWAD Project
The results of the study
show clearly
that the focus of KAWAD should be on water resource management as
opposed to
water resource development. Water
resources
in the watersheds are close to being fully developed and, in general,
constructing check dams or new wells will only change the pattern of
water
abstraction and use (i.e. such activities will not make additional
water
resources available). Although the study
findings suggest a rather gloomy state of affairs, one positive
conclusion is
that there are a large number of water management options (over 40 were
identified) that could be promoted by the project.
All these options have the potential to increase
the productivity of water use and/or
to improve equitable access to water
resources. The fundamental need is to
consider the tradeoffs associated with changing patterns of water use
and to
select options that maximise the social
and economic
value of water in any given setting at the watershed scale. In most
cases, this
means giving drinking supplies the highest priority and then allocating
water
to uses that have the next highest social and economic value.
General
Conclusions
This study has shown that
consolidating,
groundtruthing and analysing
existing information using GIS software provides important insights
into the
status of water resources in an area and the potential for making
better use of
these resources at a range of scales.
The study has also shown that such water resource auditing is a
good
starting point for identifying options that match the physical
characteristics
of an area.
Results from this study and
analysis of
information from watershed development projects in other dryland
areas of
-
Increases
in net agricultural production on arable and non-arable lands;
-
Development
of village-level institutions;
-
Substantial
improvements in the livelihoods of some social groupings;
-
Implementation
of an approach that has widespread political and public support.
The less positive aspects
of the programme in dryland
areas
include:
-
Certain
groups capture water resources often at the expense of the poor;
-
New
village-level institutions are usually outside government and,
consequently,
they often they have minimal political or legislative support for any
actions
or decisions that they might take;
-
Protecting
drinking water supplies is not seen as an integral part of watershed
development;
-
Emphasis
is on development of water resources (i.e. on increasing water supplies
by
constructing check dams, rehabilitating tanks etc.) and not on
management of
water resources (i.e. on managing demand and on maximising
the social and economic value of water).
-
As
planning takes place at the village-level, a whole range of wider
issues are
ignored (e.g. upstream-downstream equity, inter-village equity, flood
protection, drought preparedness, pollution of water courses,
biodiversity and
protection of rare habitats etc.)
-
Watershed
development publicity or propaganda (e.g. wall paintings, street plays
etc.) is
often misleading in that suggests that there are quick fixes to
water-related problems
in semi-arid areas.
General
Recommendations
The watershed development programme in
-
Planning
and water resource management should take place at basin and watershed
levels
as well as at the village level.
Village-level ownership and decision-making are fundamentally
important
but
village-level decisions should be made
within a wider
planning framework;
-
Emphasis
should be on long-term management of resources at all levels even
though this
may not be attractive to bureaucrats and politicians who want a quick
fix or
another glittering initiative;
-
Fundamental
rights to drinking water need to be protected such that demand is met
throughout the year and during years of good and bad rainfall;
-
Watershed
development guidelines and funding procedures need to be changed so
that a much
wider range of activities and interventions are promoted;
-
Incentives
and disincentives are needed that encourage individuals and groups to
make more
equitable, efficient and productive use of water;
-
Legislative
support needs to be given to community action;
-
Steps
need to be taken to reduce the frequency and impact of corrupt
practices on all
resource management practices;
-
Finally,
resource audits should be used as a starting point for all watershed
development and livelihood projects. It
is a tragedy that so much effort goes into collecting resource-related
information
that is not made available to potential users or even demanded by
potential
users and as a consequence, financial and human resources are often
wasted.
Acknowledgements
Funding for the KAWAD Water Resources
Audit came primarily from the
1 Water Resources
Management Ltd., Tavistock,
2 Soil Conservation
Institute,
3 Karnataka Watershed
Development Soc.,
This
paper, kindly provided by Dr Batchelor, is case Study 12 of the FAO E-Workshop: ‘Land-Water Linkages in Rural
Watersheds’. 18 Sept -
27 Oct.2000.
http://www.fao.org/ag/agl/watershed/
.oOo.
GOOD LAND HUSBANDRY
T.F.Shaxson
The nature of land
Varied places are part
of the land, each given character
by the ongoing
differing interactions between its components
of geology, topography, hydrology,
soils, flora and fauna, and climate.
People’s actions modify these interactions and thus affect the
character
of the land. Thus though we give
ourselves rights to modify and use it, we also have obligations to
husband it
so as to maintain its integrity, usefulness, productivity and
capacities for
self-regeneration (which reside in its organic materials and processes)
beyond
managing it for short-term profit alone.
For all situations,
good land husbandry is the process of
implementing and managing preferred systems of land use in such ways
that there
will be increase – or, at worst, no loss – of productivity, of
stability or of
usefulness for the chosen purpose. This
definition is applicable to land under every sort of use, from wild
reserves
through agricultural, pasture and forested land to urban areas.
Farmers who are
concerned to maintain their livelihoods on
the land make day-to-day decisions about the combined management of
their
crops, livestock, fields and pastures,
and husband them to the best of their abilities. (see
p.24). Where husbandry of land has been
inadequate in the past, it may have become damaged and less productive,
requiring more effort and inputs to maintain the farms’ output,
repair the damage and promote soil regeneration.
In the context of agriculture, land
husbandry can be described more specifically as the care and management
of land
for productive purposes : only through good
land
husbandry can the land’s productive potentials be enhanced and
sustained.
Improving land
husbandry requires the promotion of
integrated and
synergistic resource management systems, whose key components are:
-
Build-up of organic matter on and in the
soil, to provide both protection to the surface and a substrate for
soil
organisms’ soil-building actions;
-
Integrated management of
plant-nutrition with locally-appropriate
and cost-effective combinations of organic+inorganic,
on- and off-farm sources of plant nutrients;
-
Better crop management in terms of
improvements in seeds, crop establishment, weed control, residues
management,
and integrated pest management;
-
Better rainwater management to increase
infiltration and soil moisture, minimise risk of rainsplash,
runoff and erosion, and, where possible, benefit groundwater;
-
Better soil management to feed the
organisms,
maintain or increase effective rooting depth, avoid or break induced
compacted
layers at or below the surface, and optimise soil porosity for both
root growth
and maintaining availability of soil moisture through roots for
transpiration
and growth processes of plants.
-
Reclamation and restoration (if technically
feasible and economically justified) of land severely damaged in whatever way
(physically, biologically, chemically)
and by whatever cause (e.g. erosion, waterlogging,
pollution) to bring it back to
usefulness, productivity and sustainability.
Because it is farm
families who make decisions
about land husbandry, its
improvement also needs the adoption of
people-centred learning approaches to enable farmers to learn
about, and
investigate for themselves, the benefits and costs of different methods
of
husbandry which are satisfying, productive and
simultaneously conservation-effective, and which they can
sustain.
Similarly,
community-based and
participatory approaches to planning and technology development are
important
so that rural people can build their inherent skills, enthusiasms and
capabilities to formulate and
implement their own development plans, and to develop and disseminate
their own
improved technologies for husbandry.
In addition, in most
situations
help with developing profitable market opportunities offer prospects
for
generating income, which provide strong spurs for innovation and
improvement. Sustainable improvement
can derive from conservation-effective business decisions which provide
early,
substantial and tangible economic, social and environmental benefits
which
last.
Important shifts in
advisers’ focus
Significant shifts in
advisers’ commonly-held views on
management of land and conservation of water, soil and productivity may
be
necessary before they may more-effectively advise and assist farmers to
improve
their husbandry of the land. Examples
of such shifts include:
-
From:
considering many farmers to be ignorant and irrational,
-
towards:
acknowledging the details of what farmers know of their own social, economic and bio-physical
environments, and the rationality of their decision-making in these
contexts;
-
From: people’s
participation in outsiders’ plans,
-
towards:
outside advisers and agencies’
participation in and contribution to individuals’ and communities’ own
plans;
-
From: seeing
land conservation, production and
economics as primary concerns,
-
towards:
the community, and development of its abilities to manage its own
environment,
as the more appropriate focus for development assistance;
-
From:
catchments and the people who inhabit them as the ‘logical’ unit for
planning
of best use of natural resources,
-
towards:
the community and the land it occupies as the optimum focus and
integrator of
technical disciplines, in the context of local catchments;
-
From: preoccupation
with the significance of soils’
solid particles in the erosion process,
-
towards:
recognising the importance of the spaces between and
within aggregates of soil particles with
respect to water retention and root growth;
-
From:
physical conservation works alone on the surface against runoff,
-
towards: improvements above,
on and in the soil to improve
water infiltration.
Signs that people’s
husbandry of land has improved include
the following:
-
In the light of new insights, knowledge and
understanding, people’s interest and skills have been keenly applied
and
resulted in improved productivity, stability and sustainability of
their chosen
land uses;
-
A higher plateau of potential and
realised productivity
attained, expressed as increase in mean
yields of plants without a recurrent
need for increasing levels of external inputs;
-
Yields more stable than previously, in the
face of climatic vagaries, especially those of rainfall;
-
Soil structure and porosity in better
condition, due to improved surface protection against damaging
rainfall, and
less damage (frequency and severity) by compaction and tillage;
*
Depth of topsoil increasing (evidenced by
organic matter perceptible to greater depth) due to optimum
combinations of any
loosening by tillage, organic matter
addition, better water relations, and more vigorous rooting;
*
From a time-sequence of rainstorms of a
given intensity, significant decreases in erosion and runoff;
*
Less
surface stormflow and increased
volume and
regularity of streamflow from
natural
catchments where large proportions of their surfaces have been affected
by
improved land husbandry.
.oOo.
ORGANIC AND INORGANIC
COMPONENTS
FOR
SUSTAINABLE SOIL PRODUCTIVITY
T.F.Shaxson.
The debate about
‘organic’ vs. ‘inorganic’ production has
become too polarised. People who
want
to eat food free of agro-chemicals have to pay a large premium. Many castigate ‘conventional’ farmers
for
supposedly poisoning the soil. Passions
and polemics rise, and the middle way is ignored by many.
In the ‘western /
advanced / industrialised’ nations soils
often have relatively large reserves of plant nutrients because of
prior
applications of fertilisers for decades past, which, added to soil
weathering
products, can provide a bank of nutrients on which organic farming can
capitalise. This is seldom the case
in
tropical/subtropical areas of resource-poor small farmers where
climates can
rapidly oxidise organic matter and erosion depletes topsoils.
Almost all agricultural
systems are open-ended with
respect to plant nutrients, which leave the farm via the long drop and
the
market, and Peter is robbed to pay Paul more often than we like to
admit to
keep the offtakes and inputs in balance. Examples were shown from the Ethiopian
highlands and lowlands; tea gardens in
Kenya; and in comparisons of nutrient
contents of commonly-applied crop
residues, manures and leguminous covers vs. needs of a maize crop of 2
tons of
grain and 3 tons of stover.
From crop-yield data
over 10 or more years in e.g. UK (Rothamsted),
India (Pantnagar), and Nigeria (Zaria),
there is evidence of a more-than-additive
/synergistic effect of using FYM together with inorganic fertilisers,
likely
relating to multiple effects of organic matter plus biological
processes as
they affect soils’ CEC, micronutrient supply, chelation
capabilities, P-fixation, substrate for earthworms and other organisms,
and
top-down weathering.
Without adequate soil
moisture plant nutrients from
whatever source are not used efficiently.
Rainwater is an unregarded
resource, even
though it is a key component in soil productivity, and its management
deserves
closer attention both for minimising water stress in plants and for
increasing
and smoothing streamflows’ reliability.
‘Fertilisers poison the
soil’ is a common
misapprehension. The supposed
effects
are most likely related, in fact, to farmers tending to abandon the
active
application of organic-matter to soils once fertilisers, as
easier-to-use
sources of nutrients, become available to them.
This results in
degradation of soil architecture and associated hindrances to plants’
functioning. It is better that the
synergies noted above be aimed for during the search for sustainability
As poverty-stricken
rural populations rise and average
farm-size falls, making best use of available organic materials and
rainwater
together with what fertilisers can be afforded seems the only way
rapidly to
simulate bush-fallow benefits.
Broad-field systems are giving place to smaller round-the- house
plots
where production potential can be high;
work, rainwater, organic materials and processes, and fertiliser
materials can be concentrated at individual planting positions.
The success of
residue-based zero-tillage (as in
In conclusion, the
middle way should emphasise the
individual and joint values of both inorganic and organic materials,
plus the
soil organisms and soil water that enable the functioning of the
soil/root
complex. Increasing organic content
and
biological activity in soils re-forms them from the top down; they are materials
and processes that
can diminish, by stealth, the man-induced ‘menace of erosion’.
Inorganic fertilisers
alone cannot supplant the organic
roots of sustainability. Organic
materials alone cannot satisfy open-ended systems’ demands for plant
nutrients
at the rate at which we remove them from our land-use systems.
Summary of a talk at
Tropical Agriculture Association (W.Region)
meeting on 8.11.00
.oOo.
“The correct approach is to
find out how to use
land productively without destroying it – not to decide first how we
are going
to use it and then call in the conservationist to devise a system of
protective
measures which will be imposed on this”.
R.M.Cormack,
1952
.oOo.
‘RECLAIMED
LAND – EROSION CONTROL, SOILS AND ECOLOGY’
edited by
Martin Haigh
The editor of this book, Martin Haigh,
is WASWC Vice-President for
This
book is about the reclamation of land damaged by coal-mining. It is the first volume of a new series
that
aims to publicise the work done to restore and manage land that has
been
damaged by human activities. It is
intended that each volume will explore a particular land management
problem
from the perspective of the applied scientist and progressive
practitioner. Each will seek to make
an overview of recent
research findings and the experience of recent practice.
The intended level will lie between research
literature and advanced text books. All
will be aimed at finding systems of self-sustainability.
The reclamation of mined land is a rather specialised field of soil and water conservation and, although a number of books have been written on the subject, to my knowledge this is the first to concentrate on the problem of sustaining the quality of the reclaimed land over the long term. The book is made up of fourteen essays compiled by a team of experts from seven countries and covers a broad range of experiences, geographical areas and an array of key issues. It points out that many past attempts to reclaim mined land have failed or have been of only limited effectiveness. This has been due largely to a lack of understanding of the complexity of land reclamation and the reliance on engineering structures, which all require maintenance and have a limited life. The case is strongly made that long-term, successful reclamation depends upon the use of ecological principles and a sound understanding of soils. In the end, the success of a reclamation scheme depends upon the creation of a suitable rooting medium and the development of a living, self-sustaining and self-regulating soil system. The key to this is the soil organic system.
Reviewed
by David Sanders.
‘Land Reclamation
– Erosion Control, Soils and Ecology’ has been published by A.A.Balkema,
Note from Martin Haigh: “This is the first
volume of the new series ‘Land Reconstruction and
Management’.
These will be joint ISBN+ISSN publications, 1or 2 per year –
300pp,
peer-reviewed, international, green-tinged.
These works aim to bridge the gap between textbooks, practice
and
research, and to have a practical/applied orientation.
Vol. 2 will be about the ‘Ecological Impacts
of Roads’. Vol. 3 is expected to be
on
‘Land Husbandry in Practice – Case Studies’.
I will be delighted to use this series to promote ABLH,
officially, and
Land Husbandry in general.”
.oOo.
‘THE
PROBLEM OF MAINTAINING SOIL FERTILITY IN
J.R
Simpson, J.R.Okalebo
and G. Lubulwa.
“Few land management studies have received as
much attention recently as that of Tiffen
and
co-workers in the Machakos District of
Kenya. The idea that more people can
lead to less
erosion, at first glance, flies in the face of conventional wisdom,
which has
frequently implicated population pressure as a major cause of soil
degradation. But more than two
decades
ago, Boserup hypothesised
that increasing population pressure increases the intensification of
land use,
and this can stimulate the introduction of innovations resulting in an
increase
in productivity. So what are the
realities?
The
point of
entry for the present review is that although better land management
practices
are being implemented in several eastern African districts, such as Machakos,
progress is slow. Tiffen and co-workers previously emphasised
the beneficial effects of contour banks and terraces in reducing soil
loss by
erosion. They also recognised
that soil fertility had continued to decline but did not advance any
strategies
for maintaining soil fertility. The
Simpson et al. review takes off from this point by considering
the
history and progress of previous research on soil fertility
maintenance,
particularly in the ‘medium potential’ areas of the ‘moist savannah’ of
eastern
Africa, along with information from areas in southern Africa. It also incorporates the findings of
ACIAR (Australian)-supported
research in Machakos and Kitui
Districts in eastern
A
major
strength of the Simpson et al. review is that it combines
quantitative
information on soil fertility status and decline, and the need for both
organic
and inorganic nutrient inputs, with the economic aspects of maintaining
soil
fertility. Farmer experience with
soil
fertility management is discussed along with the slow and uneven adoption of
promising technologies,
the main reasons being the limited education of farmers regarding
available
options and poor assistance with selecting them.
A
strong
case is made for further on-farm research employing the
farmer-back-to-farmer
paradigm, with supporting modelling
studies linked
closely with a continuing extension effort.
In contrast to the rather simplistic view of Tiffen
and co-workers that soil fertility maintenance problems in Machakos
can be solved with little outside help, the review authors conclude
that the
problem of integrated nutrient management requires not only further
on-farm
research
but effective education and extension, and appropriate credit
facilities. Possible
options and interactions for soil
fertility management in a typical Machakos
mixed-farming system are outlined and these could form the basis of a
future
research agenda. Although integrated
nutrient management is identified as a key area, it would have been
useful to
have had some more specific recommendations for further work.
Donors
increasingly require that the findings of agricultural research be
communicated
to the scientific public, extensionists,
and policy
makers. Whereas publications in
scientific journals are likely to continue as a major tangible output
from
funded research, review reports which aim to integrate new research
with
previous work provide a potentially effective way of communicating
research
findings. Such is the case with the
present Review of Relevant Research.
The authors and ACIAR are to be commended for producing a
comprehensible
and very useful review of research relating to soil fertility
maintenance,
which is one of the key factors in preventing soil degradation in this
important part of eastern
Copy
of a Review by Prof. J. Keith Syers,
ACIAR
Monograph No.41. 60 pp. $Aust. 20.00
.oOo.
‘MANEJO
ECOLOGICO
La Agricultura en Regiones
Tropicales’
(ECOLOGICAL
MANAGEMENT OF SOIL:
Agriculture
in
Tropical Regions)
5th edition
- ? 1986.
499pp.
This
book was originally published in Portuguese, and has been translated
into
Spanish. As far as I know, it has
not yet
been translated into English, but it ought to be.
The author is a Professor at the
Although I have only
acquired and read Chapters 7-10, what
the author emphasises is enough to recommend the whole book to anyone
concerned
with the conservation-effective management of soils in the tropics.
The
elements of management are covered in the first eight chapters: 1.Physiology of Plants in the Tropics; 2.The Root; 3.The Soil;
4.Organic Material; 5. Biology of
the Soil; 6.Microbiology of the
Soil.; 7. Bio-structure of the
Soil; 8. Fertilizers and plant
nutrition. In the second part –
‘Ecological Management of Tropical Soils’ - the two chapters are: 9.
Management of the Soil; 10. Special Soils.
From my own perspective of improving land husbandry, Chapter 7 provides the core of the author’s approach: that lasting fertility of soil depends on preserving and, where needed, regenerating water-stable aggregation in the soil, so that movements of air, water and roots are optimised, enabling plants to grow at full capacity. This has to be achieved through care and management of the soil organisms whose dynamisms transform organic matter into humic materials and gums which together with mineral particles make up soil crumbs. Where this characteristic is lost, lesser porosity of the soil results in runoff and erosion – not the other way round! Also, where there is inadequate