Lecture 3 - Tropical Cropping Systems Flashcards
cropping system
refers to growing a combination of crops in space and time
an ideal cropping system should…..
use natural resources efficiently, provide stable and high returns, and does not damage the environment
commonly practiced cropping systems
crop rotation, intercropping, mixed cropping, relay cropping
crop rotations in cool temperate systems (like Canada)
1 crop per season (rotate different crops each year)
occasional double crop/winter crop
winter is part of cropping system as pest management
common example of western Canada cereal based cropping system (4 yrs)
Yr 1: pulses
Yr 2: cereal
Yr 3: cereal
Yr 4: oilseed
benefits of crop rotation
diversification of production
positive effects on next crop
source of N and organic matter
breaks cycle of pests
what needs to be considered abut effects of 1 crop on another
will residual herbicides/chemicals affect subsequent crop
are there shared diseases
is the previous crop greedy/ take up a lot of moisture and nutrients
what does cropping intensity mean
number of crops per year
what is the cropping intensity in cooler and warmer climates
one in cooler temps
2 in warmer temps
3 if it is hot and irrigation is used
how is cropping intensity sometimes expressed
as a decimal meaning average intensity for area
what are some ways 2 or more crops are grown on the same field in a year
sequential cropping
relay intercropping
full intercropping
sequential cropping
one crop after the other
relay intercropping
2nd crop seeded before 1st crop is finished
full intercropping
2 or more crops grown at the same time
methods of intercropping
broadcasting seed of both crops (mixed intercropping)
main crop planted in rows, other crop broadcasted
main crop and intercrop planted in rows (row intercropping)
second crop planted before 1st crop matures (relay intercropping)
economic benefits of intercropping
greater yield
insurance against crop failure or unstable market
financial stability
lower inputs
improvement of forage quality
agronomic benefits of intercropping
organic matter increases
improve soil fertility
reduction of pests/disease
restore biodiversity
environmental benefits of intercropping
promotion of biodiversity
soil conservation through ground cover
carbon sequestration
limitations of intercropping
extra work in planting, crop management, and harvest
complex interactions between intercropped plants
mechanization
what are some of the hypotheses for why there are reduced pests in intercropping
1: disruptive crop hypothesis
2: natural enemies hypothesis
3: trap crop hypothesis
disruptive crop hypothesis
2nd plant disrupts ability of pest to attack host crop efficiently
natural enemies hypthesis
more predators and parasites in intercrop
trap crop hypothesis
2nd plant species attracts pest, keeping it away from more vulnerable crop
alley cropping
crops planted in alleys between hedge rows of woody species
effects of trees on crops
shield smaller, shade-tolerant crops
stabilize temps
permanent reservoirs for parasitoid and predators
decompose organic matter
supply nutrients and mulch via leaf litter
example of alley cropping
rubber trees and rice. Rice is planted in the water ways between trees until the canopy closes
when is there no advantage to plant competition
if both plant species are aggressively pursuing resources in the same niche
what does plant competition or compatibility depend on
crops species or cultivar
density
arrangement
timing of planting each crop
interspecific
between different species
intraspecific
between members of the same species
when is competitive production an advantage
if the interspecific competition is less than the intraspecific competition due to different use of resources
benefits of facilitation in intercrops
one species modifies environment for benefit of second species and improves soil resources and pest management
how would you calculate intercrop advantage
LER (Land Equivalent Ratio)
LER (Land Equivalent Ratio)
amount of monoculture land needed to produce same yield as intercrop (basically if it worth intercropping)
LER equation
I1/M1 + I2/M2
I - grown as intercrop
M - grown as monocrop
what does it mean if LER> 1
intercrop is more efficient
what does it mean if LER < 1
monoculture is more efficient
