Soil Fertility The status of soil with respect

Soil Fertility The status of soil with respect to its ability to supply the nutrients essential to plant growth. Soil Science Society of America

Introduction to Soil Fertility • Factors Affecting Plant Growth – Precision Ag 1. Soil Characteristics 2. Crop Variety 3. Pests 4. Crop Rotation 5. Tillage 6. Compaction 7. p. H 8. Herbicides 9. Subsoil 10. Fertilizer placement 11. General fertility 12. Plant population

Introduction to Soil Fertility • Phenotics – Ultimate limitation - energy source • Photosynthesis – Duration and intensity – Latitude and climate – Establishes the ultimate yield level • Genetics – Improved genetics has increased yield potential • Higher yields due to improved genetics may require more nutrients – Breeding for adaptation to different fertility conditions

Introduction to Soil Fertility • Soil Water – A common growth limiting factor • Water required for life • Source of H and O – Water use efficiency related to plant nutrition – Movement of nutrients in soils and plants • Temperature – Limits of survival -35 to +75 °C • Practical limits 5 to 40 °C (40 - 100°F) – Species and variety differences – Microbial activity – nutrient cycling

Introduction to Soil Fertility • Biotic Factors – Weeds, diseases, insects • Weeds compete with crops for nutrients • Diseases and insects can limit yields and inhibit nutrient uptake • Atmosphere – Source of CO 2, N 2 – Plants respond to higher levels of CO 2 – Acid rain • Soil physical properties (Soil Quality) – – – Texture Water holding capacity Structure Root growth Gas movement

Introduction to Soil Fertility (Homework) • Genetics, Temperature, Moisture, Light Corn Growth Curve May June July Time Aug Sept

Introduction to Soil Fertility • Principle of Limiting Factors – The level of crop production can be no greater than that allowed by the most limiting of the essential plant growth factors.

Introduction to Soil Fertility • General Characteristics of Response Curves Plant Response • Diminishing Returns Curve Growth Factor (Fertilizer)

Introduction to Soil Fertility • General Characteristics of Response Curves Plant Response Yield (bu/A) – Response Data Example Data 150 Fertilizer (lb/A) 100 50 0 30 60 90 120 150 Growth Factor - Fertilizer Applied (lb/A) Yield (bu/A) 0 35 30 90 60 115 90 130 128 150 132

Introduction to Soil Fertility • General Characteristics of Response Curves Plant Response Yield (bu/A) – Experiment repeated over years and locations 150 100 50 0 30 60 90 120 150 Growth Factor - Fertilizer Applied (lb/A)

Introduction to Soil Fertility Plant Response • General Characteristics of Response Curves Growth Factor