Crop Production Exam 2

Characteristics of a natural ecosystem

More diverse, system stability during environmental distress, greater use of resources,

Characteristics of an Agroecosystem

manmade, used to produce food, feed, fuel, and fiber, simplified system that relies on technology and inputs (pesticides, herbicides, fertilizers, irrigation), features improved crops and livestock, increased productivity, more soil erosion, more vulnerable to pests, disease, oversimplification of food chain, and high reliance on inputs. 

how do people influence agroecosystems

fertilizer, pesticides, herbicides, breeding, monoculture, tillage, irrigation, soil erosion

allelopathy 

one plant releases toxins to inhibit the growth of another species (ex: Rye and Walnut)

monoculture

planting one cash crop in the field

continuous cropping

same crop 2+ years in a row(Corn-Corn-Corn)

crop rotation

crop is varied from year to year, can have same crop back-to-back like (corn-corn-soybean)

polyculture/intercropping

planting multiple cash crops in the same field during the same season

double cropping

utilizing the environment to produce 2 crops in one growing season

Conservation options in agroecosystems

Riparian buffer, grass waterway, shelterbelt, and CRP land

Benefits of crop rotation include

break pest/disease cycles, spread economic risk, improve soil fertility

five soil forming factors

CLORPT: CLimate, Organisms(vegetation), Relief (topography), Parente material, Time

water boundaries in soil

Wilting point- soil holds water so strongly plants can’t get it. Field capacity- amount of water the soil holds before runoff occurs. Plant availability- amount of water between WP and FC

bulk density’s role in compaction

Bd is measure of compaction, high bulk density indicates high compaction, problem with root restriction, water restriction, depleted oxygen/gas exchange, and lower soil biology

Cation Exchange Capacity

clays are negatively charged, so positive cations stick to clays, roots can alter soil chem through root exudates (mixture if sugars, amino acids, and proteins (microbe food)) to pop cations off the soil colloid. Soil organic matter can increase CEC

what particle size is responsible for CEC

clay

C:N effect on decomposition and nitrogen cycle

microbes love carbon, and need nitrogen. Low C:N = fast decomposition, High C:N = slow decomposition

how do different textures effect water storage, nutrient holding, planting depth?

Loam= happy mix of all particle sizes. Sand has bad water storage and nutrient holding clay has good; sand warms up sooner in spring, clay stays colder longer.

potassium (potash) deficiency in corn

phosphorus deficiency in corn

nitrogen deficiency in corn

Mass Flow

nutrient assimilation pathway, nutrientrs desorb from soil colloid into soil-water solution, plants pull soil water into roots through transpiration, accounts fro much of nutrient uptake

diffusion

nutrient assimilation pathway, nutrients move from high to low concentration

root interception

roots comingle with soil colloid and extract nutrients

four R’s

Right source, Right Rate, Right Time, Right price

pH’s effect on nutrients

pH below 5.5 phosphorus becomes ties to aluminum and is not plant available, exceeds 7 phosphorous becomes tied to calcium and is not plant available. ideal range is 6-7

GDD formula

GDD= ((daily max temp-Daily min temp)/2)-base min

corn GDD critical range

50 degrees low and 86 degrees high

requirements of seed germination

water, oxygen, heat

how does soil texture impact planting depth

clay and loam need shallower planting depth, sand can be planted deeper.

equipment best for precise spacing requiremnets

planters

no till

no tillage, use specialized planters, minimizes soil erosion and maximizes soil organic matter and soil water conservation

strip till

specialized equipment creates tilled narrow seedbed for row crop planting

good soil conditions for uniform germination

good soil conditions include right moisture level, good aeration, adequate soil temperature, and good seed to soil contact.

mounded rows

no primary tillage, used for row crops, about 6-inch-high mounds, crop is planted in ridge, the mound warms up faster than the surrounding ground. 

conservation tillage

leaves more than 30% of crop residue. ex: ridge-till, strip-till, no-till

herbicide resistance

tolerance of weed species that were once suceptible

weed seed bank

the reserve of viable weed seeds present on throughout the soil profile. all old and new seeds, as well as any rhizomes, tubers, bulbs, or other vegetative structurees. 

why are weeds competitive in agroecosystems

They compete for the same resources as other crops such as light, water, nutrients, and space. They establish faster in the disturbed soil, use resources more efficiently, and can outcompete crops. 

application timing for herbicides

Pre-plant, pre-emergent, post-emergent, post-harvest

historic plant diseases

Phytophthora infestans (late blight of potatoes), Claviceps purpurea (Ergot of Rye), Puccinia graminis (Wheat Stem Rust) all are fungal diseases

disease prevention methods

have good soil health, crop rotation, remove residue/till under

role of vectors in spreading diseases

they create a wound for viruses and some bacteria to enter through

parts of the disease triangle and how to manipulate

Susceptible host (rotate crops, resistant varieties), Pathogen (fungicides, kill vector), Conducive environment (increase air circulation, do not overwater, focus on soil health, tillage, planting date (establishes outside the pathogen growth window), planting population)

what soil conditions create a susceptible environment for fungal diseases

compaction, saturated soil (inadequate drainage), poor nutrients, low pH

Wheat Stem Rust

Management: resistant varieties, eliminate barberry bushes, fungicide

Damping off in Soybeans

later planting date, seed treatments

Sudden death syndrome

common in poor soil conditions resistant varieties, seed treatments, eliminate nematodes, crop rotation, fix yuh soil

Scab/Fusarium Head blight

till residue, rotate away from grass crops, fungicides at flower time

ergot of rye

resistant varieties, planting date, and fungicides

powdery mildew

resistant varieties, planting date fungicides

white mold

disease resistant varieties, chem, bio control, crop rotation, reduce planting population

soybean cyst nematode

can complete life cycle in 4 weeks and live in soil for 10 years, feed on roots of soybeans, can adapt to resistant varieties

types of metamorphosis

complete metamorphosis (example a butterfly) and incomplete metamorphosis (example a grasshopper)

lifecycle management for corn rootworm

adult version is a beetle, should be scouting during the silk stage to evaluate population and risk levels, should spray in egg stage which is late summer and fall. 

life cycle management for aphids

based on population threshold, decide when to take action. they reproduce most rapidly in the late spring/early summer, so this is the most critical time to spray.