Lecture 12 Flashcards
clay soils have a ________ buffering capacity than sandy soils
higher
soils with higher organic matter have a ________buffering capacity
higher
what are 3 ways to lower the soil pH?
add S compounds (e.g. elemental sulphur, ferrous sulphate, ammonium sulphate)
N fertilizers
add acidic organic matter (e.g. peat,
sewage sludge)
how do you raise the soil pH?
liming (adding calcium carbonate)
how do you improve soil fertility? (5)
fallow
add organic matter - green or animal manures
compost
organic fertilizers
inorganic fertilizers
fallow
Leave land uncultivated for one or more years to allow for nutrient release through natural mineralization and to replenish soil moisture
how does fallowing improve soil fertility?
allows mineralization of nutrients & water storage to improve the fertility of the land in the following year
what 2 methods of improving soil fertility are restricted by limited land?
fallow
adding organic matter
what are the 4 components of a healthy soil?
nutrients
proper structure
proper aeration
proper ability to hold water
what are the probs with fallow? (2)
small land base
Deterious soil quality (unsustainable)
what are the ways that fallow is deterious to the soil quality? (4)
Reduces organic matter
Interrupts soil microbial activity
Mobile elements subject to leaching
Vulnerable to erosion
GREEN manure
A crop that is grown and incorporated back into the soil
what are the benefits of green manure? (7)
adds organic matter
Improve soil structure, aeration, aggregation
makes nutrients available (or returns them)
Protect the soil from erosion & leaching
improves soil microbial activity
weed control
Provides habitat for beneficial organisms
what is a challenge with green manure & why?
limited space
planted after early season crops (e.g. radish, lettuce, spinach)
Planted in areas that are set aside
what are the factors necessary to consider prior to applying green manure?
How much time will it have to grow?
soil moisture conditions
how it will be “terminated” & integrated into the soil
what type of plant should be used in an urban setting to grow green manure? & what are some exs?
annual
legumes - soybean, peas, vetches, lentil
non-legumes - oat, rye, barley, buckwheat, canola, mustard
or a mix
why are legumes beneficial to use as green manure?
fix nitrogen & adds them into the soil with a symbiotic rhizobium
what needs to be added when growing legumes? & why?
appropriate inoculant to facilitate N fixation
Important to maintain appropriate C:N ratio (10:1)
when selecting a green manure plant, the biomass production should match the _______ ________-
moisture conditions
what legumes are planted in higher moisture conditions?
Soybean/peas
what legumes are planted in lower moisture conditions?
Vetches/lentil
when do you terminate green manure & incorporate it into the soil? (3)
10-12” high and/or before seed set
Before freeze up in heavy soils
early spring in lighter soils
how do you terminate green manure? (3)
Cut with scythe
winterkill
Use blade roller or crimp roller
how do you incorporate green manure into the soil?
rotor-filling
by hand with spade
Leave on surface as a mulch
what is the purpose of animal manure? (3)
Provide essential plant nutrients
add organic matter
Improve soil microbial activity
what factors cause animal manure nutrient content to vary? (5)
animal type
what the animal was fed
Percentage and type of litter or bedding
age and degree of decomposition
degree of processing (the amount of nutrients released by microbes from the manure material)
animal manure should always be used as a soil ________ not as a ______
amendment
mulch
why should raw manure not be applied directly? (3)
May contain pathogens that can infect
humans
high levels of N & ammonia may burn young plants
May contribute weed seeds
what is the best way to apply animal manure?
incorporate the manure into the soil
how do you reduce the risk of disease transmission from animal manure? (5)
use only well-composted manure
don’t include pet or meat eating animal waste
Do not apply raw manure as a top dressing on growing vegetables
wash hands carefully
Wash and peel vegetables
