Soil Fertility and Productivity

Soil fertility

• The capacity/ability of the soil to supply the plant nutrients required by the plants for growth.

Soil fertility

• The capacity of soil to produce crops of economic value to man and maintain the health of the soil for future use.

• Fertile Soil

• it contains all the required nutrients in the right proportion for plant growth.

Soil productivity

• The capacity of a soil to support plant growth.

• 14

• Number of mineral nutrients that have been found to be essential for the growth of most plants.

Nitrogen (N)

Phosphorous (P)

Potassium (K)

Macronutrients:

• Roles:  Often limiting for plant growth.

Calcium (C)

Magnesium (Mg)

Sulfur (S)

Secondary Macronutrients:

• Roles: Usually not limiting for plant growth.

• Chlorine, Boron, Iron, Manganese, Zinc, Molybdenum, Copper

• Micronutrients:

• Roles: Essential for various metabolic processes and plant development.

Nitrogen (N)

• Importance:  Essential component of nucleic acids, proteins, and chlorophyll.

• Functions: Stimulates root growth and development, contributes to lush foliage growth.

Phosphorous (P)

• Importance:  Critical to energy storage and transfer, cell division, and early root growth.

• Functions:  Contributes to healthy flower, fruit, and seed formation.

• Sources:  Mainly from the decomposition of organic matter.

Potassium (K)

• Importance:  For ion balance, enzyme activation, carbohydrate metabolism, and photosynthesis.

• Functions:  Regulates uptake of nitrogen, sodium, and calcium.

• Benefits:  Helps plants develop strong root systems and disease resistance.

• Calcium (Ca)

• Importance:  For cell wall development, cell division and elongation, nitrate uptake and metabolism, and protein synthesis.

• Magnesium (Mg)

• Importance: Essential for plant photosynthesis and involved in enzyme activation.

• Sulfur (S):

• Importance:  Important component of proteins, fats, and some defensive compounds in plants.

Dark-colored soils

Loamy texture soils

General Assumptions in Determining Fertility Status of a Soil:

Dark-colored soils

Assumed to be fertile and high in soil organic matter.

• Loamy texture soils

• Assumed to be more fertile than sandy soils.

• Nitrogen Deficiency

• Symptoms:  Develop chlorosis (yellowing foliage), stems become thin and spindly.

• Phosphorous Deficiency

• Symptoms:  Interrupted or delayed flowering and fruit set, purplish cast on stems and leaves.

• Conditions:  Common in strongly acidic or alkaline soils and soils with high levels of aluminum.

• Potassium Deficiency

• Symptoms:  Stunting, irregular yellow leaf splotches, scorched-looking leaf margins.

• Conditions:  Also found in soils with excess calcium or magnesium.

• Calcium Deficiency

• Symptoms:  Deformity of new leaves, curling and yellowing of leaf edges, stubby brown roots, hardening of stems.

• Conditions:  Due to high acidity, excessive amounts of potassium, drought.

• Magnesium Deficiency

• Symptoms:  Yellowing of older leaves, especially between leaf veins, thin, curling foliage, brown spotting on leaf stalks.

• Conditions: Usually associated with acidic, sandy soils or with excess potassium or calcium.

• Sulfur Deficiency

• Symptoms:  Yellowing of leaves, plants will be spindly and small.

• Organic Fertilizer

• Definition:  Materials derived from plant and animal droppings, such as weed residues, tree pruning, urine, green manure, farmyard manure, crop residues, and others.

• Functions:  Used to fertilize the soil.

• Grazing Livestock:  Play an important role in nutrient flow to cropland.

Nitrogen, Phenols, Lignin

• Plant Quality:  Plants contain three substances that define their quality as organic fertilizer:

• Nitrogen

• Essential for plant growth.

• Phenols

• Substances in plants that make them rot slowly, reducing fertilizer quality.

  • Identification:  Astringent taste indicates high ______ content.

• Lignin

• Plants that are woody contain a lot of lignin, which slows down decomposition and fertilizer quality.

  • Identification:  Difficult to tear apart indicates high _____ content.

Earthworms

• Role:  Play a key role in the recycling of soil nutrients and improve their availability to plants.

• Feeding Habits:  Feed on dead and decaying materials.

• Nutrient-Rich Dung: Excrete nutrient-rich dung.

Promotion:  Promoted by the abundance of good compost.

• Vermiculture

• Growth of earthworms in organic wastes.

Vermicomposting

Processing of wastes using earthworms.

Liming

• Importance:  For soils to be productive, they must be in the optimum pH range (5.5 to 6.5 for most crops).

• Function:  To neutralize soil acidity.

• Cover Cropping

• Definition:  Planting alongside or interspersed with other crops to cut soil-eroding wind, prevent overexposure to the sun, and stimulate a healthy soil system.

• Using Wastewater for Irrigation:

• Benefits:  Wastewater contains most of the essential elements of fertilizer in the proper amounts.

• Potential:  Could dually contribute to healthier urban areas and provide vital, organic fertilizer to rural areas.

• Reintegrating Livestock

• Importance:  Many farmers rely on farm animals for their livelihoods.

• Benefit:  Animal manure can be an effective and inexpensive way to boost the health of organic topsoil.