exam (temperate cropping) Flashcards
definition of a cropping system
crops, their sequence + their management. both adapted to a given environment
cropping system equation and meaning of each variable
G x E x M
G = genotype (species and variety)
E = environment (climate/soil)
M = management decisions made by farmers (pesticides, row spacing, rotation,tillage
Norman Borlaug
Nobel prize winner, introduces pest resistance and semi-dwarf varieties of wheat, higher N acceptance
credited for the green revolution
green revolution
G x M
new varieties have higher yield initially, can take more nitrogen before plateauing.
examples of G x E change
n ont cropping systems
the growing season is getting longer and warmer
grain corn and soybean production in N ont increasing
corn heat units growing steadily
corn - corn crop rotations
increased popularity in ont bc of economics, operation type and tech adoption
rootworm an issue, BT reduces footwork risk but resistance is increasing
rootworm
corn pest
typical in corn-corn rotation, needs 2 years for life cycle
adults feed on silks in July/aug, then lay eggs in the soil. larvae eats corn roots next year
BT corn to kill off footwork but resistance is increasing
change in canada cropping systems over time (farm:total)
then - 1 in 3 in 1931, 1 in 50 now # of farms decreased but avg acres increased
Canadian cropping systems “before”
crop-livestock integration is greater, more manure Fert, forages, more diverse rotations on smaller fields. lots more rotations and forages/small fields. required for weed management
Canadian cropping systems now
larger farms and fields,
mechanization, simplified rotations, simplification and separation of livestock and crop farmers, larger % rented land, hay can be used as a cash crop.
main ag regions in Canada
northern corn belt, peace river valley
ont, qc, w canada, Manitoba.
S and SE ont, E qc is main region, northern corn belt.
parries have diversity in the region, dry, short growing season
N. BC, N ab, peace river valley, grows a lot of seed products
4 secular trends in CDN cropping systems
- decline in forage production in e canada
- summer fallow all but eliminated in canada
- wheat and canola big winners in w canada
- domination of corn and soybeans, decline of small grains in E canada
true/false: farmers will always choose to max profit/yield
false, max yield is rarely profitable, also have to manage risk, enviro costs, and personal preferences
plant vs crop performance
performance of one individual does not define the entire field. management that increases yield of individual does not always increase all of the crop. most temperate crops on a per crop basis, tropical plants usually on a per plant
yield equation: meaning, too many characters to make the actual thing an equation
based mostly on light. from planting to harvest, PAR, fraction of PAR intercepted by crop canopy, radiation use efficiency (crop biomass/PAR), harvest index
harvest index meaning and equation
fundamental measurement of temperate crop productivity. biomass always expressed at 0% for HI,
grain yield/total crop biomass
lieges law of the minimum
1843, yield is regulated by the limiting factor, yield can only be increased by correcting the limiting factor.
crop management should focus on correcting the limiting factor one by one until no more limitations
mitscherlichs law of the maximum
1909, only true in high yielding environments, each factor limits yield by only ~10%, final result is greater than the sum of the effects bc each effect multiplies, aim at correcting many factors together to get multiplicative yield effect.
law of conservation of matter
matter is neither created nor destroyed
nutrient balance calculation importance
can be created by calculating inputs and output on the farm, can account for nutrient pollution,.
meaning of a negative nutrient balance in the soil:
more exports than imports, nutrients are being mined from soil resevoir
meaning of positive nutrient balance in the soil
exports < imports, nutrients are being accumulated or lost through pollution/ unmeasured pathway
sustainable definition
possible to continue indefinitely.
implications for nutrient management re: conservation of matter
every part of a nutrient can be accounted for in cropping systems via a nutrient budget, nutrient mining results in unsustainable cropping systems
available vs unavailable nutrients (how to make nutrients more available
only a fraction of nutrients in top 30cm of ont soil is available/yr.
manage to make them more available
- adjusting soil pH to increase nutrient availability, increase rooting depth, allowing crops to explore more soil
traits favoured in agriculture:
- improved cooperation with other plants in species
2. improve competitiveness against weeds
leaf area index (LAI)
meter squared of leaves/meter squared of ground area
maximized LAI for soybeans
3, diff crops require diff LAI for max PAR.
ways to change the LAI
row spacing, seeding rate
importance of even emergence
maximizes yield, early emerging plants will dominate later plants, yield loss from dominated plants is greater than gained yield from dominant plants
decisions for crop management
residue management, manure/fert. application,
importance of residue management
reduces wind and water erosion, decompose or become SOM, decomp releases co2 and nutrients.
leaving residue reduces erosion by 95%.
downside of crop residue
- mulches soil, keeping it wetter and colder
- habitat for insect pests
- prevents seed-soil contact during planting.
suggestions for crop residue management
tillage, or reduce tillage, 30% cover to prevent erosion.
no till, yield drag associated, not a silver bullet.
stubble burning in India, not canada, baling residue, animal feed
does no till increase SOC (sequestration?
yes in w canada most are no till, and no till increases yields consistently, no in e canada, 30% or less are no till.
which are the only Fert appllied in full?
P and K, n will be lost entirely over winter and early spring.
phosphorus runoff and consequences
surface erosion and minimal drainage, ~1% P lost to water, bit more to erosion. adds up and causes algae blooms
fert appliction rate
meet uptake needs not satisfied by the nutrients supplied naturally in the soil.
nutrient demand = function of soil organic matter, prev crop residue, mineralization, pH, weather
how often should you soil test?
best practice every 3 years
winter cropping opportunities as climate warms
winter canola, winter oats
base growing temps for cotton, corn, soybeans, oats, and wheat
cotton- 15, corn - 8, soybean - 10, oats - 2, wheat - 0
wheat protein - soft
lower protein, for pastries, cookies and cake flour. 90% of ont wheat is soft red.
millers will not accept any wheat over 10.5-11% N content
wheat protein - hard
higher protein, bread, crackers, pizza dough, also used for beer. 6% of ont wheat.
diff between red and white wheat
main diff nitrogen content, fraction of storage proteins in the endosperm, water insoluble gluten,
why is planting time important for wheat
allows plant to tiller and build up sufficient nutrient/energy resources to overwinter. yield loss of 1 bu/ac for each day of delayed plantning.
wheat tillers
good! increase yield, target in the fall is 4 tillers. if wheat is planted too early and you have too many tillers it can make problems tho. inc lodging and snow mould.
perennial weed control in the fall
10-26% more effective than the sprint, small time window tho. commonly wheat/oats are more competitive anyways
“past” reasons for crop rotation
n supply
weed, diesease and insect management
integration w livestock
risk mitigation
ont crop rotations
mostly corn and soybean, or continuous of either
“present” reasons for crop rotation
yield improvement system resilience improve fert use efficiency nitrogen supply weed, disease and insect management integration w livestock labour distribution economies of scale risk mitigation soil quality
ont crop trends
livestock have big impact. soybean throughout all of ont. corn common in S and E ont Winter wheat in S ont spring cereals in E/N ont canola in N ont
Ontario crop rotations
continued corn
continued soy
corn/soy rotation
Alfalfa/ alf/alf/ corn/corn - dairy farmers
corn/soy/ ww/ - good all purpose rotation
corn/soy/high value crop
hay as a cash crop
oat/soy/ spring wheat/ canola - common in N ont
rotation effect
rotations increase soil fert, reduce disease, weed, insect pressure
M x E re crop rotation and hot dry summers
rotation effect - 15% greater yield corn and 13% greater soy yield compared to continued corn or corn/soy rotation
SOM changes in soil structure and makes it easier for crops to access water
simple vs diverse crop rotation
subjective but agreed that:
simple - 4 or fewer crops in a 4 yr period on the same field
diverse - 3 or more crops in a 4 yr period on the same field
need for drainage in ont
short growing season, field work mist happen soon as possible
wet soil prevents farmers from driving over fields, otherwise compaction
wet soils stay cooler longer, reducing germination speed, emergence, and early season growth
spring tillage
dry and warm soil, most noticeable in loamy/sand soils
pest control strategies
cultural “systems” approach
biological “native or introduced”
chemical “applied by farmer to kill/control”
ont pest management in field crop production
- variety selection - herbicide tolerant, genetic resistance, will eventually break down
- chemical control - herbicides often applied early I the season
critical weed free period
weeds present during this time dramatically reduces yield
weed presence outside of CWFP doesn’t affect yield much at all
for most crops this period is first 3-4 weeks after planting
ont weed management practicies
herbicide
crop rotatation
tillage
crop management
