WEED DETECTION FOR PRECISION WEED MANAGEMENT Kefyalew Girma SOIL/BAE 4213-2002.
Kefyalew Girma Desta Oklahoma Cooperative Extension Service Plant and Soil Sciences Department.
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Transcript of Kefyalew Girma Desta Oklahoma Cooperative Extension Service Plant and Soil Sciences Department.
IT MEANS A LOT! Improve water infiltration rate/holding capacity Supply free nutrients Decrease pests, pollution from pesticides and
heavy metals Soil pH buffer Improve soil tilth/ structure Reservoir of nutrients and water CEC C sequestration: reduce CO2 and CH4
Improve microbial mass and species diversity
OM level %
WHC, lbs Rain ,in
4-5 165-195 4-6
1.5-2 35-45 0.5-1.5
If OM<2.5%, N,P and K leach away
Water holding capacity
NT vs CT
Prior et al., 2003
Mielniczuk, 1996
pH
Infiltration
. . . IT MEANS A LOT!
Effect on CEC
Soil particle CEC (cmol/kg)
Humus 100-300Smectites (black swelling clays)
60-150
Kaolinite (white clay) 2-15
Fe and Al oxides (from ferrosols)
<1
McLaren and Cameron (1996).
Gardener et al.,2002; composting and compost proceeding
Effect on microbes, dairy manure
First thing first! What is the goal?
o Short-term nutrient supply o Slow nutrient supply
Highly decomposable material vs slow decomposing materials
Nature of the organic enterprise Soil type and problem
Building Soil OM 3-Strategies
1. Decrease losses
2. Add Organic Material/Matter
3. Consider Sustainability
1. Building Soil OM: decrease losses
Reduce tillage Erosion control
Corn, Hussain et al., 1999, SSSAJSchertz et al., 1984, ASAE, proceeding
. . . Decrease lossesMinimize monocropping
Crop Sequence Inches of topsoil remaining
Continuous Corn 7.76-year rotation* 12.2Continuous timothy grass
17.4
* Corn, oats, wheat, clover, timothy, timothy, 100 yrs Gantzer et al. 1991, AJ 83:74-77
1. Cover Crops Spring Annuals
o Oats and Triticale.
Summer Annualso Buckwheat, Cowpea, and Sorghum
Winter Annualso Austrian Winter Pea, Hairy Vetch and Winter Rye
are planted in late summer/early fall, over winter, and resume growing the following spring.
Biennials:o Yellow Blossom Sweet clover and perennials Red
Clover can be grown for longer term soil-building.
. . . Cover CropsCommon C:N ratios of cover crops
Organic Material C:N Ratio Reference
Young rye plants 14:1 (Sarrantonio, 1994)
Rye at flowering 20:1 (Sarrantonio, 1994)
Hairy vetch 10:1 to 15:1 (Sullivan, 1990)
Crimson clover 15:1 (McLeod, 1982)
Corn stalks 60:1 (Sarrantonio, 1994)
Sawdust 250:1 ((McLeod, 1982)
If we return 2.2 tons/ac/yr of residue to the soil, it will maintain soil OM at constant level in continuously cropped soils.
. . . Green ManuresBiomass and N yields of winter annual GM crops
Cover Crop Biomass tons/acre Nitrogen lbs/acre
Sweet Clover 1.75 120
Berseem clover 1.10 70
Crimson Clover 1.40 100
Hairy Vetch 1.75 110
“Green manure crops can supply an OM equivalent of 9 to 13 tons per acre of farmyard manure or 1.8 to 2.2 tons dry matter per acre.” However, the benefit from green manure crops’ soil benefits will be gone in a year or less.
Schmid and Klay, 1984
3. Animal Manure
Type N, lbs/t
P, lbs/t K, lbs/t Solids%
% PAN yr1
B density lbs/cu yard
Dairy solids 5 1 2 20 0-20 1100Beef feedlot 12 3 14 25 20-40 1400Broiler litter 73 28 55 70 40-70 900Laying hen 37 25 39 40 1400Horse 9 3 13 35 0-20 1400Sheep 18 4.0 29 28 1400
Species, feed, and handling dependent
4. Compost Low in nutrient Low availability More of OM buildup Very easy procedures available Any organic material can be composted Materials vary
Compost vs Manure?Compost Manure
slow release form of nutrients usually higher nutrient content
easier to spread sometimes difficult to spread
higher investment of time or money lower investment of time or money
lower potential to degrade water quality
higher potential to degrade water quality
less likely to contain weed seeds more likely to contain weed seeds
reduced pathogen levels potential for higher pathogen levels
more expensive to purchase less expensive to purchase
fewer odors odors sometimes a problem
improves soil tilth improves soil tilth
5. Uncomposted Yard Debris Nutrient rich/poor, depends on
material Better than compost Grass clippings release nutrients
quickly; 20 lbs N/wet ton, 5-20% is available
Wood takes for ever! Leaves and small branches
decompose quickly
6. Packaged Organic Fertilizers Easy to use Less variable More concentrated Expensive! Blended forms
Organic Fert N, (%DW)
P2O5, (%DW) K2O (%DW)
Feather meal 1-2 1-3
Steamed bone meal 7-13 20-30 <1
Dried Kelp 1-2 <1 2-15
Seed meal 6-7 2-3 1-2