Untitled Quiz

Study Notes

Improving agricultural production leads to increased soil nutrient removal, decreasing soil fertility.
Efficient nutrient management is critical for sustainable crop production.
Soil degradation affects agricultural productivity, including physical, chemical, and biological processes.
Onsite degradation includes erosion, crusting, compaction, and fertility depletion.
Offsite degradation includes sediment deposition, water contamination, and atmospheric emissions.
Soil fertility is the ability of soil to hold plant nutrients.

Soil fertility refers to soil's ability to hold and make plant nutrients available for growth.
Two types of soil fertility exist: native fertility and managed fertility.
Native fertility is the natural capacity of soil to hold and supply nutrients due to parent material and organic matter content.
Managed fertility refers to added plant nutrients and amendments.

Essential for plant growth.
16 essential nutrients, three categories:
- Macronutrients: Primary and intermediate nutrients are required in greater quantities. (N, P, K, S, Mg, Ca).
- Intermediate nutrients: Sulfur, magnesium, and calcium.
- Micronutrients: Required in smaller quantities. These include elements like iron, zinc, manganese, etc.
Deficiency of any nutrient can limit crop yield (Law of the Minimum).

Three methods:
- Root interception: Physical contact between roots and nutrients. Increased root surface area = increased interception.
- Mass flow: Nutrients transported to roots with water movement.
- Diffusion : Nutrients move from higher to lower concentrations.

Plant cells have barriers that regulate nutrient and water movement.
Passive transport: No energy required, movement with concentration gradient.
Active transport: Energy required, movement against concentration gradient.
Certain nutrients are mobile in plants and can relocate to new growth.
- Mobile nutrients: Nitrogen, phosphorus, potassium, magnesium.
- Immobile nutrients: Calcium, sulfur, boron, copper, iron, etc.

Elements that stimulate the growth of certain plants, but not all.
- Silicon, sodium, selenium.
Not required for plant growth

Nitrogen, phosphorus, and sulfur cycles are vital.
Nutrient losses through runoff, erosion, leaching, and crop removal are important.

Biological and geochemical processes involve phosphorus cycling.
Organic phosphorus compounds are hydrolyzed by phosphatase enzymes, from plant roots and microorganisms.
Weathering and dissolution of primary minerals can release phosphorus.

Sulfur can originate from weathering of parent material, atmospheric deposition, and organic matter.
Sulfur oxidation reactions occur most rapidly in warmer soils.

Plant analysis is a method to check for nutrient deficiencies, in conjunction with soil testing.
Plant tissues, like leaves and petioles, are sampled at specific growth stages.
Plant deficiencies may not be immediately visible and could be a late-season problem.

Managing soil fertility is important, and the 4R principles (right source, right rate, right time, and right place) should be followed
The Law of the Minimum: Crop yields are limited by the most deficient nutrient
Critical nutrient levels: Nutrient levels needed to support sufficient plant growth. Deficiency range, critical range, and sufficiency range.

Measuring residual soil nitrate helps determine how efficiently nitrogen is managed.
This is important for adjusting nitrogen fertilizer for the next season.