Crop science

what’s the difference between agriculture and agronomy

Agriculture is the broad science, art, and business of cultivating soil, producing crops, and raising livestock.

Agronomy is a branch of agriculture that focuses on the management of soil and production of field crops like corn, wheat, etc.

Difference between agronomy and horticulture

Agronomy focuses on the management of soil and production of field crops like corn, wheat, etc. also rather large

Horticulture focuses on special crops like fruits, vegetables, and the growth of ornamentals like house plants also quite small

What was the paradigm shift and what did the different regions grow

(paradigm shift)- transition from nomadic tribes of hunter/gatherers to sedentary agricultural communities

(fertile crescent southwest Asia)- wheat, barley, pea, flax

(Mesoamerica)- corn “maize”, beans, squash

(east Asia)- Rice, foxtail millet, soybean

Traits of domestication

Artificial selection for non-shattering seed heads, longer seed size, and loss of seed dormancy

what happened during the industrial revolution

• mechanization (steel plow, mechanical reaper, tractor power)

• Less physical labor

• drastically reduced manual labor hours

What happened during the green revolution

Dr. Norman Borlaug developed high yielding, semi dwarf wheat and rice varieties.

What else did Dr. Norman Borlaug make

• Paired genetics with synthetic nitrogen fertilizers, chemical pesticides, and expanded irrigation systems.

• Saved an estimated 1 billion people from starvation

How much must global food production increase by

%60-%70

Why is increasing global food production hard

We must do it with roughly the same amount of land while conserving water/soil resources

How much of the U.S population is involved in farming

less than 1%

What are the 4 pillars of food security, and what do they mean

Availability- enough food is produced consistently

Access- Having sufficient income or resources to obtain food

Utilization- proper biological processing of food

Stability- uninterrupted access to food, resilient against economic and weather changes

Definition of the 4 pillars of food security

When all people at all times have social/physical and economic access to safe and nutritious food

What is the definition of classification

The organization of organisms into groups based on shared characteristics

How can crops be classified “hint (6 ways)”

1. taxonomy

2. plant family

3. agronomic use

4. life cycle

5. growing season

6. growth habit

What does plant classification help with

• scientific research

• identification

• effective communication

• crop management

• crop rotation

• pest & disease management

• economic planning

How can crops be classifies by use

1. cereal grain

2. oil

3. fiber

4. forage

5. root/tuber

6. sugar

7. specialty

What are the major crop families (scientific and basic names)

• poaceae — grass family

• fabaceae — Legume family

• brassicaceae — Mustard family

• asteraceae — sunflower family

What are some crop examples in the Poaceae (grass) family

• wheat

• corn

• barley

• oats

• sorghum

What are some crop examples in the fabaceae (legume) family

• soybean

• alfalfa

• pea

• beans

What are some crop examples in the Brassicaceae (mustard) family

• Canola

• cabbage

• turnup

• radish

What are some crop examples in the Asteraceae (sunflower) family

• sunflower

• lettuce

• artichoke

What are some common characteristics of the Poaceae (grass) family

1. Monocots

2. Grain/Caryopsis fruit

3. Major food and feed crops

What are the different classifications by life cycle

• annual (one growing season)

• biannual (two growing seasons)

• perennial (multiple growing seasons)

What are some crops with an annual life cycle

• Corn

• Soybean

• Wheat

What are some crops with an biannual life cycle

• Sugar beet

• Carrot

• Onion

What are some crops with a perennial life cycle

• Alfalfa

• Orchard grass

• Apple

What are the two seasons of classification

Cool and warm season

What’s it mean for something to be a cool season crop

Performs better during cooler portions of the growing season and may have some tolerance to frost

What’s it mean for something to be a warm season crop

Performs better with warmer soil and air temp for optimal growth

What are some cool season crops

• Wheat

• Oats

• Barley

• Canola

• Peas

What are some warm season crops

• Corn

• Soybean

• Sorghum

• Cotton

• Sunflower

What are the rules of botanical nomenclature and how do you write something in it

1. Genus is capitalized

2. specific plant is lowercase

3. both italicized

Genus specific plant

Definition of species

Taxonomic unit identifying a group of organisms

Definition of cultivar

A cultivated plant selected for specific characteristics

Definition of hybrid

Offspring resulting from crossing two genetically different parents

How do plants contribute to human nutrition?

Plant directly supply most human calories and provide dietary protein worldwide

What are the primary crops

• Cereal grains (wheat, corn, rice)

• Grain legumes (soybean, pulse crops)

• Root/tuber crops

What nutritional components are supplied by crops

1. Carbohydrates (starches & sugars “primary energy source”)

2. Protein & amino acids

3. Lipids/fats (fatty acid, energy density, cell membrane health)

4. vitamins & minerals (vitamin A, iron, zinc, preventing deficiency diseases)

What are the current trends in U.S diet

• Increase in caloric intake per capita over the last 50 years

• Surges in refined grains, added fats/oils, and high fructose corn syrup (HFCS)

Factors causing current U.S trends

• Socioeconomics & cost — affordability of processed calories vs fresh produce

• Convenience & processing — value added crop processing and shelf stable foods

• Cultural & health preferences — shifts towards plant diets, organic options, and non-GMO markets

• Agronomic impact of consumer demand — market demand dictates crop rotations, acreage allocation and grain quality traits

What's an example of Agronomic impact of consumer demand

• (high-oleic soybean oil)

What are some 1st generation biofuels

• Starch ethanol — Grain corn fermented into ethanol

• Biodiesel — Transesterification of plant oils (ex. soybean, canola, palm)

How is a 2nd generation biofuel made

By converting plant cell walls (cellulose/hemicellulose) from perennial grasses like (switchgrass, miscanthus) or crop residues (corn stover)

What is the meaning of the acronym (EROI)

Energy return on investment

What does (EROI) energy return on investment mean

Net energy output versus fossil fuel inputs required to cultivate, harvest, and process the crop

What is the difference between morphology and anatomy

• Morphology (external form and structure)

• Anatomy (internal structures)

What are the morphological forms and structures

1. Shapes

2. Size

3. Arrangement

4. Appearance

What is plant physiology

The study of the processes that keep a plant alive and growing

What does plant pyhsiology connect

Stem→leaves→reproductive structure

If you thought of a plant like a system what does each part do

• roots (acquire resources)

• leaves (capture carbon and light)

• vascular tissue (moves materials)

• Cells (use energy to grow, maintain, and reproduce

What are the resources needed and what are they for

• Light (energy)

• CO2 (carbon for sugars)

• Water (reactant & transports)

• Minerals (builds tissue & enzymes)

• O2 (needed for respiration)

• Temperature (controls reaction rates)

How does photosynthesis work

Light + CO2 + H2O = Glucose + H2O

Where does photosynthesis take place?

Mainly occurs in the chloroplast of plant tissue

What does the stomata do

It allows CO2 and O2 to enter and exit the plant

What does the sugar from photosysthesis become

Fuel and building materials for growth

What is the first reaction in photosynthesis

photochemical (light)

What happens during photochemical reactions

Light, water is then split into hydrogen, oxygen, ATP, NADPH

What is the second reaction in photosynthesis

Carbon fixation (dark)

What happens during carbon fixation

CO2 is reduced to simple sugars

What are the 3 categories of CO2 capture

1. C3

2. C4

3. Cam

C3 traits

• most common

• efficient in cool/moderate conditions

• 3 carbons made

• Rubisco fixes CO2 directly to calvin cycle

C3 crop examples

Wheat and soybean

C4 traits

• Adapted to high light & heat

• better water use efficiency

• 4 carbons made

C4 crop examples

Corn and sorghum

Cam traits

• Extreme water conservation

• stomata open at night closes during day

• Calvin cycle uses CO2 while water loss stays low

Cam crop examples

Cactus and pineapple

How’s respiration work

Glucose + O2 → CO2 + H2O + energy

Whats respiration needed for

Cell maintenance and growth

Photosynthesis vs respiration

Photosynthesis — (stores energy in sugars and needs light)

Respiration — (releases usable energy from sugars, doesn’t need light, and “growing roots, seeds, and young tissue” rely heavily on it)

What’s transpiration

Water loss cools plant and causes an uptake in movement of nutrients

What’s the rate of transpiration depend on

• stomata count/size

• soil moisture

• temperature

• humidity

• wind/air movement

Where do light dependent reactions occur and what’s is make

Thylakoid membranes and they produce ATP and NADPH

Where does the Calvin Cycle occur and what’s is make

Chloroplast stroma and produces carbon compounds needed for sugars

Factors that limit growth

• (light) — low light limits energy capture

• (CO2) — low internal CO2 limits carbon fixation

• (Water) — deficit promotes stomata closure

• (Temperature) — changes enzyme activity and photorespiration

How soil forms “hint (clorpt)”

• (Cl) — climate “temperature & precipitation

• (O) — organisms “plants, microbes, and animals”

• (R) — relief “slope & landscape position”

• (P) — parent material “rock or deposited sediment”

• (T) — time “how long processes act”

what are some examples of physical weathering and whats it do

Freeze/thaw, abrasion, and roots break rocks into smaller pieces changing size more that chemistry

what are some examples of chemical weathering and whats it do

Hydrolysis, oxidation, and dissolution changes mineral chemically. Often accelerated by water and warmth

What does parent material influence

Initial mineral particle sizes and mineralogy

What do organism do

they add organic matter and help form aggregates

What’s relief and climate influence

erosion, drainage, and horizon development

What are the minerals traits

• Sand — (biggest “2-.05mm” with fast drainage and low water/nutrient holding

• Silt — (medium size “.05-.002mm” with smooth feel and moderate holding

• Clay — (smallest size “<.002mm) sticky when wet and high water/nutrient holding

Soil structures

• Granular — crumb like, topsoil, good infiltration

• Blocky — block shaped, common in subsoil

• Prismatic — vertical columns, subsoil, may slow movement

• Platy — thin horizontal plates, often compaction related

• Massive/single grain — no visible peds, clay mass/loose sand

What builds soil

• roots

• fungal hyphae

• organic matter

• biological activity

• reduced disturbance

What damages soil

• excessive tillage

• low organic matter

• compaction

• working soil when wet

What helps create aggregates

• organic & microbial byproducts

• roots & fungal hyphae

• wetting/drying & freezing/thawing

• calcium

Physical benefits of organic matter

• Improves aggregation

• Can increase infiltration

• increases water holding capacity

• reduces crusting and erosion risk

Chemical benefits of organic matter

• Stores/releases nutrients

• provides energy for microbes

• adds exchange sites and increases CEC

• helps buffer chemical changes

How’s CO2 enter the soil

• Plants — capture CO2 through photosynthesis and carbon enters soil through roots, residues, and organic amendments

• Microbes — decompose organic matter and release carbon into soil

Whats decomposition and erosion do

• decomposition (removes organic matter as microbes use carbon)

• erosion (removes organic matter rich topsoil)

Soil PH

• 1-5 acidic

• 6-7 neutral

• 8-10 in-between

• 11-14 basic

What Ph does most crops prefer

6-7.5

Whats Ph influence

• nutrient availability

• microbial activity

• potential toxicities

Why does Ph matter

• Low Ph increases (Al) and (Mn) solubility to harmful levels

• (P) can become less available at low and high Ph

• Micronutrient availability increases as Ph decreases

• Microbial activity and nutrient cycling are reduced in very acidic soils

• Ph affects fertilizer efficiency and crop suitability

What buffering capacity and what’s clay/high OM and Sand/low OM do

Buffering capacity is the soils resistance to change in Ph

• Clay/high OM — increase buffering

• Sand/low OM — decrease buffering

How to raise Ph

1. add AG lime when recommended (neutralizes acidity and rate depends on Ph and buffering capacity)

2. Incorporation speeds reaction when practical

How to lower Ph

• add elemental (S)

• Add acid forming fertilizers

• High Ph calcareous soil can be difficult to broadly change, and management often targets root zone or crop choice

What CEC stand for

cation exchange capacity

What is CEC influenced strongly by

Clay amount/type and organic matter which usually carry negative charges which attracts cations

Important Cations

• Ca 2+

• Mg 2+

• K +

• NH4 +

• H +

• Al 3+

What does a high CEC soil have

lots of negatively charged exchange sight attracting more cations