Soils

1
Soils Nutrient Management

• Feed the soil
• Not the plants

2
Characteristics of Organic Production

• Reliance on on-farm nutrient sources, fewer
  purchased inputs
• Holistic- emphasis on soil building, soil health,
  crop rotation, nutrient recycling
• Requires natural rather than manufactured
  nutrient sources
• Essentially all manufactured or synthetic
  fertilizers and pesticides are prohibited

3
Soil Fertility Practices for Organic Farming

• Crop Rotation Specifically Required 205.205
• Cover Crops Green Manures
• Composts and Manures
• Monitor Provide Adequate Minerals
• Supplementary Organic Fertilizers

4
What is Soil Structure?

• Arrangement of soil particles (sand, silt, clay)
  into groups (aggregates)
• Binding agents
• Microbial gums, fine roots, organic matter,
  fungal hyphae, iron oxides, and clay bind soil
  particles together

5
What is Soil Structure? (contd)

• Unlike soil texture, soil structure can be
  improved by management
• Soil structure also can be degraded by poor
  management
• Compaction results in a loss of structure

6
Structure - Granular

• Granular structure consists of soil particles
  held in loose, rounded aggregates

• Most often found
• At the soil surface
• In grassland soils
• In soils high in organic matter

7
Essential Plant Nutrients

• Macronutrients
• Primary
• N - Nitrogen
• P Phosphorus
• K Potassium
• Secondary
• S Sulfur
• Mg Magnesium
• Ca Calcium

Nutrients derived from the soil and/or fertilizer

• Micronutrients
• Fe Iron
• Mn Manganese
• Cu Copper
• Zn Zinc
• B Boron
• Mo Molybdenum
• Cl Chlorine
• Ni Nickel

8
DETERMINING NUTRIENT NEEDS

• Soil testing
• Nutrient deficiency symptoms
• Plant analysis

9
Importance of SOM in soil fertility

• Improves soil fertility
• Source of nutrients
• Increases ability of soil to hold and release
  nutrients gradually
• Drives soil biology
• Feeds microbes and earthworms

10
To increase organic matter

• Use different types / sources
• Cover crops/green manures
• Mulch or compost or manure
• Minimize tillage intensity
• Avoid moldboard plowing when possible

11
CarbonNitrogen Ratios of Organic Materials
12
Relative Nutrient Mobility

• Nitrogen moves much faster than phosphorus and
  potassium in the soil
• Phosphorus has very limited mobility in the soil

13
Nitrogen Pollution

• Nitrogen leaching
• Nitrate form of N
• Impairs drinking water quality
• Blue baby syndrome
• Contributes to eutrophication
• of rivers and lakes

14
Trap crops

• Amount of biomass produced is key to nutrient
  uptakegood stand, rapid growth
• Age/stage of plant when killed, determines N,
  CN, plant composition, and therefore
  decomposition rate (along with weather!) Huge
  challenge!
• Cereal rye, annual ryegrass, wheat, oats, barley

15
ATTRA, 2003
16
Residue Addition and N Availability
High carbon residues added
Avail. Soil N
Time
Mineralization(release of N)
Immobilization (tie-up)
17
Residue Addition and N Availability
Low carbon residues added
No Immobilization (tie-up)
Avail. Soil N
Time
Mineralization(release of N)
18
Onion interseeded with Red Clover
19
Red Clover seededinto corn just prior to canopy
closing in mid-June. It provides a cover crop
protecting soil and capturing nutrients over the
winter.
20
Legume Green Manure Crops

• Produce 40-200 lbs.N/acre, depending on species,
  biomass produced, N in plant
• Approx. 40-60 of N available to subsequent crop
• Incorporation of green manure into soil results
  in increased N for 4-6 weeks after this
  supplemental N may be required

21
ATTRA, 2003
22

• Organic Fertilizer
• N P2O5 K2O
• Manure (fresh)
• bat 6.0 9.0 3.0
• cattle 0.55 0.55 0.45
• hog 0.50 0.35 0.45
• horse 0.65 0.25 0.50
• poultry 1.00 0.85 0.45
• rabbit 2.4 1.4 0.6
• sheep 0.9 0.5 0.8
• Alfalfa hay 2.5 0.5 2.1
• Bone meal (steamed) 1.0 15.0 0.0
• Fish scraps 9.0 7.0 0.0
• Lawn clippings 1.2 0.3 2.0
• Leaves (sugar maple) 0.7 0.1 0.8
• Straw (wheat) 0.6 0.2 1.0
• Grain straw 0.6 0.2 2.1
• Sawdust 0.2 0.1 0.2
• Wood ashes 0.0 2.0 6.0

23
Nitrogen Recommendations

• For vegetable gardens
• N to Apply
• Organic Matter () (lb N/100 sq ft)
• _________________________________________________
  __________________________________________________
  _______
• Low (lt3.1) 0.20
• Medium to High (3.1 19) 0.15
• Organic Soil (gt19) 0.10
• __________________________________________________
  __________________________________________________
  ______
• Sweet corn, tomatoes, cole crops, and vine crops
  may need additional nitrogen at midseason (1/6 lb
  N/100 sq ft)

24
Application Methods

• Broadcast prior to planting
• Band placement
• Sidedressing
• Starter solutions
• Foliar fertilizers

25
Band Placement

• Fertilizer placed near row at time of planting
• Can get fertilizer burn if placed too close
• Place fertilizer
• 2-3 below seed
• 2-3 to the side
• of seed

26
Sidedressing

• Fertilizer placed beside plant after emergence
• Primarily used for nitrogen
• High rates may cause burn

27
Foliar Fertilizers

• Not satisfactory for N, P, K
• Cant apply large amounts without burning foliage
• Use as supplement only
• If needed, can be used for micronutrients
• Chelated iron

28
N deficiency Corn
29
N deficiency Radish
30
N deficiency Cauliflower
60 lb N/A
31
K deficiency Corn
32
Fe Chlorosis - Navy Bean