J.G. Mexal

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Soil Properties Nutrients

• J.G. Mexal
• New Mexico State University
• Las Cruces, NM

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Soils NutrientsLiebigs Law of the Minimum

• Growth and Yield are limited by the nutrient in
  least supply
• Envision a barrel with staves of different
  heights.

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Soils NutrientsEssential Elements/macronutrient
s
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Soils NutrientsEssential Elements/
micronutrients
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Tree Nutrition

• Rules of Thumb
• After water, N is the factor that most limits
  tree growth.
• N 2 of foliage DW
• Foliar fertilization works
• Fall fertilization is not bad!

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Tree Nutrition

• Nitrogen
• mobile, resulting in general chlorosis, shorter
  growth, fewer lateral breaks
• available as ammonium (NH4) or nitrate (NO3-)
• apply 1-2 kg N/100 m2 to soil surface
• apply 1 kg N/100 L to foliage (wet to runoff)

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Soils NutrientsNitrogen Content vs Ps
Net Ps rate (nmol CO2/g/s)
Death Valley annuals
Old field annuals
Deciduous chaparral shrubs
Evergreen shrubs trees
Southern African shrubs
Leaf N (mmol/g)
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Soils NutrientsNitrogen Fertilizer vs Corn
Yield
Yield (kg/ha)
64kg
363kg
576kg
128kg
704kg
832kg
896kg
896kg
1024kg
Nitrogen (kg/ha)
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Soils NutrientsNitrogen Fertilizer vs Corn
Yield
Yield (kg/ha)
Added Return (/ha)
Return
100
Yield
80
60
40
20
0
Nitrogen Applied (kg/ha)
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Soils and FertilizersRules of Thumb

• Nitrogen 2 of dry weight
• Phosphorus 10 of N content
• 0.2 of dry weight

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Tree Nutrition

• Phosphorus
• leaves turn purple
• P 10 of N content
• available as HPO4 or H2PO4-
• incorporate 1-4 kg P/100 m2 into soil

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Tree Nutrition/ nutrient stress vs
cold-hardiness
Winter Injury ()
N /P
Pecan Yield (kg/tree)
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Tree Nutrition

• Potassium
• interveinal chlorosis and margin scorching
• available as K
• rarely limiting
• incorporate 2-15 kg/100 m2 into soil

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Tree Nutrition

• Iron
• immobile in plants, new leaves become chlorotic
  often with green veins
• incorporating iron in calcareous soils is
  ineffective
• spray iron citrate or
• Sequestrene 138 for alkaline soils or
• Sequestrene 330 for acid soils (0.2 g/100L)

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Soil PropertiesSoil pH Estimate/ Lime use (1000
tons/yr)
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Fertilizer Content

• Complete fertilizer contains NPK
• Incomplete fertilizer is missing one of three
• Reading a fertilizer bag
• 101010 contains 10 N, 10 P, 10 K
• 4600 contains 45 N alone
• Mixing 100 45 0 0
• 100 045 0
• 100 0 060
• 300 151520

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Fertilizer Content
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Soils NutrientsSources of Nitrogen

• Inorganic N
• Anhydrous NH3 82
• Urea 46
• NH4NO3 33
• (NH4)2SO4 20
• (NH4)2HPO4 20
• KNO3 14

• Organic N
• Dried blood 12
• Bat guano 12
• Fish meal 10
• Cottonseed meal 7
• Sludge 6
• Cow manure 2

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Soils NutrientsSources of Phosphorus
Potassium

• Phosphorus P1
• (NH4)2HPO4 54
• TSP 45
• Cottonseed meal 3
• 1 P as P2O5

• Potassium K2
• KCl 50-60
• KNO3 46
• Wood ashes 4-10
• Seaweed 4- 5
• 2 K as K2O

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Fertilizer Rules!/ adapted from Vir.Tech

• DONT GUESS -- TEST!
• Virginia pine maintain soil pH between 5.0 and
  6.0
• Eldarica pine maintain soil pH between 6.5 and
  7.5
• Dont waste on expensive fertilizers unless
  soil or tissue analysis shows a need.
• Band fertilize in Years 1 and 2
• Broadcast fertilizer beginning Year 3
• Apply P in the spring
• Apply Ca in the fall
• Maintain soil test calcium at 50-60 saturation
  and Mg at 10-15 saturation. Use lime or gypsum.
• If more than 100 lb K/a is needed, apply muriate
  of potash in two applications or only in fall
  because of potential fertilizer burn.

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Interpreting Soil Test Results--NM
Flynn 2002
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Tree Nutrition/ Hartman et al.2000
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Put the Fertilizer where the Roots Are!
RoT The radius of root extension height of tree
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Nitrogen Rates for Virginia pine- NCSU
Tree age Application Spring Fall (years)
Type -------oz/tree------- 1 Band 0.5
- 2 Band 0.5 - 3
Broadcast 0.5 0.5 4 Broadcast
0.5 0.5
http//www.agr.state.nc.us/agronomi/stnote5.htm
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Nitrogen rates for Virginia pine- NCSU
Tree age Application Spring Fall (years)
Type -------oz/tree------- 1 Band 0.5
- 2 Band 0.5 - 3
Broadcast 0.5 0.5 4 Broadcast
0.5 0.5
http//www.agr.state.nc.us/agronomi/stnote5.htm
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Fertilizer Recommendations/ Vir.Tech

• Preplant or at planting 1 oz/tree
• Year 1 0-46-0 _at_ 500 lb/ac
• Year 2 10-10-10 _at_ 2-3 oz/tree
• Year 3 10-10-10 _at_ 3-4 oz/tree
• Year 4 10-10-10 _at_ 4-5 oz/tree

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Fertilizer Recommendations/ Vir.Tech

• Preplant or at planting 1 oz/tree
• Year 1 0-46-0 _at_ 500 lb/ac
• Year 2 10-10-10 _at_ 2-3 oz/tree
• Year 3 10-10-10 _at_ 3-4 oz/tree
• Year 4 10-10-10 _at_ 4-5 oz/tree

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Fertilizer Recommendations

• NCSU and Virginia Tech recommend 2.2 to 2.5 oz
  N/tree over 4 years
• Is that enough?

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Biomass Growth of Eldarica Pine /Sammis et al.
2002
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Nitrogen Uptake of Eldarica Pine /Sammis et al.
2002
4 g N/tree
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Nitrogen Fertilizer Recommendations/

• Yr-1
• 2-3 applications (late)
• Total N 0.5 oz/tree (15 g)uptake 4 g/tree
• Yr-2
• 3-4 applications (Spring-Fall)
• Total N 2.0 oz/tree (60 g)uptake 20 g/tree
• Yr-34
• 3-4 applications (Spring-Fall)
• Total N 3.0 oz/tree (90 g)uptake 90 g/tree

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Fertilizer Uptake Estimates- Eldarica pine-23 mo
96 g N
72 g N
48 g N
24 g N
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Fertilizer Recommendations/-GroBag
Where do you fertilize Gro-Bag trees?

• Root exploration is restricted
• Fertilize more like a container-grown tree
• You do not want much root development outside the
  bag

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Foliar Sampling

• Collect
• in September
• 5-8 needles of current- season growth
• 15 locations on tree
• 20-30 trees
• analyze for N, P, K, Ca, Fe, Mo, B, S

Sample current- year needles in this area.
Bondi, et al. OSU CES 2000
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Foliar Nutrient Content/ Hartman et al.2000
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Why is foliar testing important?
Bondi, et al. OSU CES 2000
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Fertilizer Recommendations
Bondi, et al. OSU CES 2000