1.1 Managing Soil Fertility - Center for Agroecology and Sustainable

26 Pages·2003·0.1 MB·English

by  Martha Brown

1.1 Managing
Soil Fertility
Introduction 3
Instructor’s Lecture 1 Outline: Soil Fertility Management—
Concepts, Goals, and Components 5
Detailed Lecture 1 Outline for Students 9
Instructor’s Lecture 2 Outline: Sustainable Agriculture Practices 15
Detailed Lecture 2 Outline for Students 19
Assessment Questions and Key 23
Resources 25
2 | Unit 1.1
Managing Soil Fertility
Introduction: Soil Fertility Management
UNIT OVERVIEW MODES OF INSTRUCTION
“Feed the soil to feed the plant” is a > LECTURE (2 LECTURES, 3 HOURS TOTAL)
Lecture 1 presents the concepts, objectives, and compo-
basic principle of organic farming
nents of sound soil fertility management programs for
and gardening. This unit introduces
certified organic production systems. Lecture 2 describes
students to the ways that farmers the sustainable agriculture practices (e.g., tillage, cover
crops, composts, soil amendments) that go into organic
and gardeners develop and maintain
fertility management.
soil fertility in certified organic
> ASSESSMENT QUESTIONS (0.5 HOUR)
farming systems. Lectures describe
Assessment questions reinforce key unit concepts and
the objectives and components of
skills.
soil fertility management and the
various practices used to develop LEARNING OBJECTIVES
and maintain fertile soil. It should be CONCEPTS
emphasized throughout the lectures • Certified organic agriculture as defined by the U.S. federal
that the overall goal of a fertility government’s National Organic Program
management program is to balance • Sustainable agriculture
nutrient inputs and outputs and • Soil fertility in organic and sustainable farming systems
ensure a good balance of nutrients
• Soil quality
for the crop. This balance requires a
• The relationship amongst soil fertility, plant health, and
complex mix of soil management the resistance and resilience of crop plants to pests and
activities including proper tillage, pathogens
irrigation, crop residue management, • Goals of a sustainable fertility/soil management program
weed management, and crop • Components of a soil fertility management program
rotation planning. Neglecting any of
• The role and impacts of tillage
these components can compromise
• The role of cover crops in the organic management of soil
soil quality, affect crop performance, fertility
and create potential pollution
• The use of composts, manures, and other organic
problems due to nutrient runoff or amendments
leaching. • Management and the concept of nutrient budgets
• Considerations in the design of crop rotations
Unit 1.1 | 3
Introduction Managing Soil Fertility
4 | Unit 1.1
Managing Soil Fertility
Lecture Outline 1: Soil Fertility Management—
Concepts, Goals, and Components
for the instructor
A. Pre-Assessment Questions
1. What are some of the environmental concerns associated with the use of agricultural chemicals?
2. What are some of the human health concerns associated with exposure to agricultural chemicals?
3. What is organic farming?
4. What would be the goals of an organic and sustainable soil fertility management program?
5. What would be the major components of a soil fertility management program?
6. How would you define soil quality?
7. How would you define soil fertility for an organic farming system?
B. Organic Agriculture
1. “Certified Organic” agriculture as defined by The National Organic Program (NOP;
www.ams.usda.gov/nop/)
2. Requirements for organic certification under the NOP
a) Organic System Plan
b) Necessary components of an Organic System Plan
i. Practices and procedures used
ii. Characterize each substance used as a production input
iii. Identify the monitoring techniques that will be used to verify that the organic
plan is being implemented
iv. The record-keeping system used to preserve the identity of organic products
v. Management practices and physical barriers established to prevent commingling
of organic and non-organic products
vi. Information deemed necessary by the certifying agent to evaluate site-specific
conditions relevant to compliance with program regulations
3. “Sustainable agriculture” defined: A broader, more inclusive definition (see www.sarep.ucdavis.edu)
C. Soil Fertility and Soil Quality in Sustainable Farming Systems
1. Soil fertility and soil quality defined
a) Soil quality (see soils.usda.gov/sqi/)
b) Soil quality indicators
i. Accepts, holds, releases, and mineralizes nutrients and other chemical constituents
ii. Accepts, holds, and releases water to plants, streams, and groundwater
iii. Promotes good root growth and maintains good habitat for soil organisms
iv. Resists degradation
v. Maintains good soil structure to provide adequate aeration and tilth
vi. Good soil structure allows for rapid water infiltration
vii. Moderate pH (6.0–7.5)
viii. Low salinity levels
ix. Low levels of potentially toxic elements
x. Balanced fertility
Unit 1.1 | 5
Instructor’s Lecture 1 Outline Managing Soil Fertility
c) Soil fertility: The capacity of a soil to provide nutrients required by plants for
growth; one component of soil quality
2. Soil fertility, plant health, and the resistance and resilience of crop plants to pest and pathogens
D. Goals of a Sustainable Soil Fertility Management Program
1. To sustain high crop productivity and crop quality in food and fiber production
a) Crop productivity, crop quality, and the success of a given operation
2. To minimize risks to environmental quality and human health associated with
agricultural production
a) Important steps in minimizing human health risks, and on and off-farm impacts
i. Avoid the use of all synthetically compounded materials; balance inputs of
organic matter and mineral inputs to avoid exceeding crop needs
ii. Avoid creating nonpoint source pollution through surface runoff and leaching
iii. Prevent soil erosion and sedimentation of waterways
iv. Close nutrient cycles as much as possible within the field and farm
v. Close nutrient cycles at multiple scales: watershed, regional and national scales
E. Components of a Sustainable Soil Fertility Management Program: The Means to Achieving the
Above Goals
1. Improve and maintain physical and biological properties of soil
a) Sustainable agricultural practices used to improve and sustain soil physical and
biological properties
i. Maintaining or building soil organic matter (SOM) levels through inputs of
compost and cover cropping
ii. Properly timed tillage
iii. Irrigation
iv. Sound crop rotations, soil amending, and fertilizing techniques all serve to improve the quality of
agricultural soils, which in turn affects soil quality and crop performance
2. Improve and maintain chemical properties of soil
a) Benchmarks of optimal soil chemistry
i. Balanced levels of available plant nutrients (see Unit 1.11, Reading and Interpreting
Soil Test Reports)
ii. Soil pH ~6.0–7.0
iii. Low salinity levels
b) Sustainable agricultural practices used to develop and maintain optimal soil chemical properties
i. Provide a balanced nutrient supply for the crop
ii. Conduct soil sampling and periodic monitoring
iii. Conduct plant tissue testing
iv. Time seasonal nutrient release from organic amendments to correspond with crop requirements
• The quality of the organic matter input
• Environmental factors such as soil temperature and moisture
v. Avoid leaving fields bare to avoid wind and water erosion and nutrient leaching
vi. Manage irrigation carefully to avoid runoff, erosion, and leaching of soluble nutrients
vii. Supply major nutrients primarily through organic matter and mineral soil amendments
viii. Allow sufficient time for fresh residue to break down before planting crops
ix. Use in-season supplemental fertilizers when necessary
6 | Unit 1.1
Managing Soil Fertility Instructor’s Lecture 1 Outline
3. Minimize disease/pest susceptibility
a) Sustainable agriculture practices used to minimize disease/pest susceptibility in
organic farming systems
i. Maintain soil nutrient levels and soil pH within optimal range
ii. Build and maintain soil organic matter to promote desirable soil physical
properties and supply essential plant nutrients
iii. Maintain soil moisture within optimal ranges for plant growth and the
avoidance of compaction and erosion
iv. Design appropriate rotations to break pest cycles
v. Plant polycultures
vi. Use appropriate preventative and active biocontrol practices
4. Summary
The sustainable farming practices described above, including crop rotations, soil amending
and fertilizing, tillage, and irrigation techniques, must be used in concert to improve and
maintain the quality of agricultural soils. Soil quality in turn affects crop performance
(yield) and the resistance and resilience of crop plants to pest and pathogens.
Unit 1.1 | 7
Instructor’s Lecture 1 Outline Managing Soil Fertility
8 | Unit 1.1
Managing Soil Fertility
Detailed Lecture Outline 1:
Soil Fertility Management—
Concepts, Goals, and Components
for students
A. Pre-Assessment Questions
1. What are some of the environmental concerns associated with the use of agricultural chemicals?
2. What are some of the human health concerns associated with exposure to agricultural chemicals?
3. What is organic farming?
4. What would be the goals of an organic and sustainable soil fertility management
program?
5. What would be the major components of a soil fertility management program?
6. How would you define soil quality?
7. How would you define soil fertility for an organic farming system?
B. Organic Agriculture
1. “Certified Organic” agriculture as defined by The National Organic Program (NOP;
www.ams.usda.gov/nop/)
Organic production: “A production system that is managed in accordance with the Act
(The Organic Foods Production Act [OFPA] of 1990, as amended in the NOP) to respond to
site-specific conditions by integrating cultural, biological, and mechanical practices that
foster cycling of resources, promote ecological balance, and conserve biodiversity.”
Further, it is a system of agriculture that encourages healthy soil and crops through such
practices as nutrient and organic matter recycling, crop rotations, proper tillage, and the
strict avoidance of synthetic fertilizers and pesticides for at least three years prior to
certification.
2. Requirements for organic certification under the National Organic Program
a) Organic System Plan: The NOP requires that all crop, wild crop, livestock, and handling
operations requiring certification submit an organic system plan to their certifying
agent and, where applicable, the State organic program (SOP). The organic system plan
is a detailed description of how an operation will achieve, document, and sustain
compliance with all applicable provisions in the OFPA/NOP. The certifying agent must
concur that the proposed organic system plan fulfills the requirements. The organic
system plan is the forum through which the producer or handler and certifying agent
collaborate to define, on a site-specific basis, how to achieve and document
compliance with the requirements of organic certification.
b) Necessary components of an Organic System Plan
i. The organic system plan must describe the practices and procedures used, including
the frequency, in the certified operation
ii. Second, it must list and characterize each substance used as a production input
iii. Third, it must identify the monitoring techniques that will be used to verify that the
organic plan is being implemented
iv. Fourth, it must explain the record keeping system used to preserve the identity of organic products
Unit 1.1 | 9
Students’ Lecture 1 Outline Managing Soil Fertility
v. Fifth, the organic system plan must describe the management practices and physical barriers
established to prevent commingling of organic and non-organic products
vi. Finally, the organic system plan must contain the additional information deemed
necessary by the certifying agent to evaluate site-specific conditions relevant to
compliance with these or applicable State program regulations.
3. “Sustainable agriculture” defined (see www.sarep.ucdavis.edu)
Sustainable agriculture can be defined as an approach to agriculture where the aim is to
create environmentally sound, economically viable, and socially just food and agricultural
systems. Maximum reliance is placed on locally or farm-derived renewable resources and
the management of self-regulating ecological and biological processes and interactions in
order to provide acceptable levels of crop, livestock, and human nutrition, protection from
pests and diseases, and an appropriate return to the human and other resources
employed. Reliance on external inputs, whether chemical or organic, is reduced as far as
possible. The objective of long-term sustainability lies at the heart of organic farming and
is one of the major factors determining the acceptability of specific production practices.
Sustainable agriculture is not just the conservation of non-renewable resources (soil,
energy, minerals) used to produce food and fiber. Sustainable agriculture also
encompasses maintenance or restoration of the environmental quality of surrounding
landscapes; the economic viability for all involved in agricultural production; and more
equitable distribution of agricultural products to assure that basic human needs are met
(see Unit 3.4, Sustainable Agriculture and Food Systems).
C. Soil Fertility and Soil Quality in Sustainable Farming Systems
1. Soil fertility and soil quality defined (see soils.usda.gov/sqi/)
a) Soil quality: The capacity of a soil to function, within land use and ecosystem boundaries, to sustain
biological productivity, maintain environmental quality, and promote plant, animal, and human health
b) Soil quality indicators
i. Soil accepts, holds, releases, and mineralizes nutrients and other chemical constituents
ii. Soil accepts, holds, and releases water to plants, streams, and groundwater
iii. Soil promotes good root growth and maintains good biotic habitat for soil organisms
iv. Soil resists degradation (e.g., erosion, compaction)
v. Soil maintains good soil structure to provide adequate aeration
vi. Good soil structure allows for rapid water infiltration
vii. Soil has a moderate pH (~6.0–7.0) at which most essential soil nutrients are available
viii. Soil has low salinity levels
ix. Soil has low levels of potentially toxic elements (e.g., boron, manganese, and aluminum)
x. Balanced fertility that provides adequate levels of macro- and micronutrients that
plants and soil microbes require
c) Soil fertility: The capacity of a soil to provide nutrients required by plants for growth.
This capacity to provide nutrients to crop plants is in part influenced by the physical
properties of soils and is one component of soil fertility. Desirable soil physical
properties and the capacity of the soil to provide nutrients for growing crops are both
soil quality indicators.
2. Soil fertility, plant health, and the resistance and resilience of crop plants to pest and pathogens
Soil fertility requires a balance of critical plant nutrients and either deficiency or excess of
nutrients can adversely affect plant growth, susceptibility to pests, and post-harvest
quality
10 | Unit 1.1
Managing Soil Fertility Students’ Lecture 1 Outline