Soil Quality and Management

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SOIL QUALITY AND
MANAGEMENT
Submitted by: Submitted to:
Avin Kharel (16) Asst. Prof. Roshan Subedi
IAAS, Lamjung Campus IAAS, Lamjung Campus (TU)

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INTRODUCTION
The state of a wide variety of soil qualities is referred to as soil quality or health. Healthy soil
allows for the production of healthy, high-yielding, and nutritious crops with minimal
environmental effects. Such healthy soil also ensures property stability as well as crop
development and health in the face of changing natural (often weather-related) or human-
caused conditions. Surface crusting, depth accessible for root exploration, pH, salinity, cation
exchange capacity, mineralizable nitrogen, presence of plant diseases, soil microbial biomass,
and other elements all contribute to soil quality and its attributes, which have a significant impact
on crop development. Surface crusting is a significant problem for many soils in both tropic and
temperate regions (Sumner & Stewart, 1992).
Physical properties (water holding capacity, infiltration rate, soil depth horizon, soil texture, soil
bulk density, aggregate stability, dispersible clay), chemical properties (nutrient availability,
electrical conductivity, cation and anion exchange capacity), and biological properties (nutrient
availability, electrical conductivity, cation and anion exchange capacity) are all inherited from
natural soil (Soil organic matter, soil microbial biomass, soil respiration, mineralizable organic
carbon, vegetative growth, and cover). Working on too wet clay soil causes natural aggregates to
break down, lowering soil tilth, intensive cropping with no crop rotations, allowing soil salinity to
build up under irrigation or allowing organic matter content to drop too low, and pollution with
potentially toxic metals or synthetic organic chemicals are all factors that contribute to soil
degradation. A "soil quality index" to compare various soils is being developed. There is currently
no agreed-upon method for determining soil quality. However, practically every key property
that contributes to soil quality is influenced by soil organic matter. As a result, it's crucial to
recognize and emphasize the importance of crop and soil management for organic matter
accumulation and maintenance in the development of high-quality soils.
The Nature of Soil Organic Matter
3 different general types of organic matter occur in soils i.e. living organisms, active dead organic
matter (slightly or undecomposed, labile), and well-decomposed (humidified) relatively stable
materials. These all have an equally important role in maintaining and improving soil quality. Soil
living organisms include microscopic viruses, bacteria, fungi and protozoa, small and medium-
sized arthropods, earthworms, and so on. The overwhelming number of groups of soil organisms
feed either on crop and other organic residues and their activities help in recycling nutrients,
keeping pest population low in number, producing substances that promote building soil
aggregates, and producing humic substances. All organisms need access to a range of elements
in available forms as well as energy. Green plants derive their energy from sunlight through the
process of photosynthesis. In the food web, primary consumers are those soil organisms that are
the first to utilize crops and other residues as energy materials. Secondary consumers are those
organisms that prey upon primary consumers. Tertiary consumers include ground beetles,
centipedes, and ants. They feed primarily on other soil organisms.

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Biological Diversity of Soil Organisms
The creation of circumstances for a diverse variety of soil organisms should be a key goal of
successful crop and soil management. Biological variety in the soil is critical for the health and
stability of agroecosystems. Cropping and residue management have an impact on microbial
communities. In general, transitioning from natural ecosystems to agroecosystems reduces the
diversity of species and the amount of microbial biomass. The population dynamics of soil
organisms can be influenced by soil and crop management. Complex crop rotations, huge
amounts of various types of agricultural residues and manures, cover crops, and reduced tillage
is all examples of techniques that foster a biologically diversified population of soil organisms.
Similarly, the use of mulches or just leaving residues on the soil surface will promote the
populations of surface-feeding organisms like earthworms.
Active organic matter is made up of the active portion of dead components in fresh residues as
well as residues that have only been partly degraded. These residues appear in soils as roots and
are absorbed into above-ground residues, where they are relatively easy to degrade by soil
organisms. The organic matter associated with sand size minerals decomposes quickly, however,
there is some evidence that a portion of the organic matter associated with clays mineralizes
quickly and serves as a significant supply of nitrogen. Humus refers to the well-decomposed and
largely stable part of soil organic matter. It is tightly connected with the clay and silt fractions and
has a long residence time in the soil. Soil humus decomposes slowly, with only around 2 to 5%
decaying per year. The majority of the cation exchange capacity of organic materials is found in
humus.
Role of Organic Matter in Soil Quality
Despite accounting for a small percentage of soil weight, the amount and type of organic matter
determine practically all of the attributes that contribute to soil quality. Organic matter has a
variety of consequences on soil's physical, chemical, and nutritional qualities, as well as biological
properties.
The binding nature of sand, silt, and clay particles help to maintain proper tilth and soil physical
conditions for plant growth, among other things. Sandy soils with higher organic matter levels
have more tiny pores to retain accessible water for plants and are less prone to drought. Organic
matter-rich soils have greater aggregation, are less dense, and allow for better root penetration
and development than soils with low organic matter levels.
Chemicals and nutrients are also abundant in organic stuff. Organisms in the soil break down it
and convert organic forms of elements into plant-available forms. In addition, organic matter is
a major source of the cation exchange capacity where it helps to store available nutrients and
protects them from downward leaching by water.

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Soil organic matter also contributes to biological variety. Soils with effective crop rotations have
a more diversified community of organisms and, as a result, provide a better biological
environment for plant growth than soils depleted of organic matter.
Plants produced in soils rich in organic matter are healthier and less prone to pest damage than
those grown in soils low in organic matter due to physical, nutritional, and chemical impacts.
Furthermore, when soil organic matter is abundant, the existence of a diverse population of
organisms helps to create a less hostile pest environment for crop plants.
Nutrient Flows and Cycling
Soil organic matter is important in nutrient cycling because it serves as a source of cation
exchange capacity as well as a storehouse of nutrients that are gradually transformed into usable
forms by biological activity. Because the vast majority of soil organisms take part in the
breakdown process, they aid in nutrient recycling. Nutrients would be accessible in quantities
and relative portions that matched or coordinated with the growing crop's absorption needs. The
contamination of ground and surface water with fertilizers is a key issue in nutrient cycling in
conventional agricultural agriculture. The comparatively high amount of available nutrients in
conventional agriculture production may increase insect infestation susceptibility and lower the
nutritional content of the food produced. Nutrients would be present in available forms in
quantities and relative proportions that matched or coordinated with the uptake needs of
growing crops in an ideal nutrient cycle.
Crop and Soil Management Strategies for Promoting Soil Quality
The best way to develop high-quality soil is to manage crops and soils to promote the buildup
and maintenance of high organic matter levels, including a good amount of active organic matter.
It is clear that there are only two primary ways to build up and maintain good quantities of
organic matter in soils i.e. a) Increase the rate of organic matter addition to soils. b) Decrease the
rate of organic matter loss.
The various techniques and strategies for organic matter management are:
i) Better utilization of Crop and other organic residues
ii) Practice good crop rotation
iii) Use of cover crops
Integrating animals into cropping systems
 Use of Manure
 Reduced Tillage
 Erosion control
 More Efficient use of Nutrient cycles