Soil Nutrient Sources and NutrientUptake - Agronomy

61 Pages·2006·3.16 MB·English

by  Dale Leikam

Soil Nutrient Sources
and NutrientUptake
Photosynthesis
Plants use light energy and chlorophyll to make sugars for
plant growth from water and carbon dioxide.
Light and
Chlorophyll
6 CO + 12 H O C H O + 6O + 6H O
2 2 6 12 6 2 2
Carbon dioxide Water Glucose Oxygen Water
Functions of Nutrients in Plants
• Carbon, Hydrogen and Oxygen make up 95% of the dry
matter weight of plants.
– Carbon dioxide from air is converted in the plant to sugars, starches,
proteins, enzymes, and a multitude of other organic compounds.
– Oxygen is a component of most organic compounds, must be present
for plant roots to function.
– Hydrogen and oxygen form water which makes up most of the weight
of living plants. Hydrogen is a constituent of most organic compounds
and is involved in many of the chemical reactions in the plant.
17 Essential Plant Nutrients
Source of Plant Nutrients
From Water
From Air
Hydrogen (H)
Carbon (C)
Oxygen (O)
Oxygen (O)
From Soil
Nitrogen (N) Calcium (Ca) Boron (B)
Phosphorus (P) Magnesium (Mg) Chlorine (Cl)
Potassium (K) Sulfur (S) Copper (Cu)
Iron (Fe)
Manganese (Mn)
Molybdenum (Mo)
Zinc (Zn)
Nickel (Ni)
SOIL ORGANIC MATTER
Partially decomposed residue of plants, animals,
etc. Humus is the more stable residue 1-3%
decomposes annually
Soil Organic Matter
-
• Improves soil structure, water holding capacity, etc.
• Provides for good soil tilth
• Provides CEC
• Source of essential plant nutrients
(cid:57) 90-98% of N abd S
(cid:57) 30-50% of P;
(cid:57) Micronutrients
Soil Microbes Mineralize and
Immobilize Plant Nutrients.
Inorganic nutrients
Organic nutrients
Mineralization
Plant Unavailable Plant Available
Form Form
Immobilization
Factors Affecting Organic Matter Levels
(cid:137) Temperature
(cid:137) Precipitation
(cid:137) Drainage
(cid:137) Vegetation
(cid:137) Tillage
Erosion
(cid:137)
Effect of Temp and Moisture on Soil Organic Matter
Soil Organic Matter Content
Changes Since Cultivation
Estimated Residue Production by
Various Crops ??
lb per bu yield
Wheat 100
Corn 60
Sorghum 60
Soybean 45
Sunflower 36
NRCS – calculation factor