J.G. Mexal New Mexico State University Las Cruces, NM Soil Properties: Nutrients

Soils & Nutrients Liebig’s Law of the Minimum Growth and Yield are limited by the nutrient in least supply Envision a barrel with staves of different heights.

Soils & Nutrients Essential Elements/macronutrients

Soils & Nutrients Essential Elements/ micronutrients

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!

Tree Nutrition Nitrogen –mobile, resulting in general chlorosis, shorter growth, fewer lateral breaks –available as ammonium (NH 4 + ) or nitrate (NO 3 - ) –apply 1-2 kg N/100 m 2 to soil surface –apply 1 kg N/100 L to foliage (wet to runoff)

Soils & Nutrients Nitrogen Content vs Ps Leaf N (mmol/g) Net Ps rate (nmol CO 2 /g/s) Death Valley annuals Old field annuals Deciduous chaparral shrubs Evergreen shrubs & trees Southern African shrubs

Soils & Nutrients Nitrogen Fertilizer vs Corn Yield Nitrogen (kg/ha) Yield (kg/ha) 1024kg 896kg 832kg 704kg 576kg 363kg 128kg 64kg

Soils & Nutrients Nitrogen Fertilizer vs Corn Yield Yield (kg/ha) Nitrogen Applied (kg/ha) Added Return ($/ha) Return Yield

Soils and Fertilizers Rules of Thumb Nitrogen = 2% of dry weight Phosphorus = 10% of N content » 0.2% of dry weight

Tree Nutrition Phosphorus –leaves turn purple –P ~ 10% of N content –available as HPO 4 = or H2PO 4 - –incorporate 1-4 kg P/100 m 2 into soil

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

Tree Nutrition Potassium –interveinal chlorosis and margin scorching –available as K + –rarely limiting –incorporate 2-15 kg/100 m 2 into soil

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)

Soil Properties Soil pH Estimate/ Lime use (1000 tons/yr)

Complete fertilizer contains N:P:K Incomplete fertilizer is missing one of three Reading a fertilizer bag –10:10:10 contains 10% N, 10% P, & 10% K –46:0:0 contains 45% N alone Mixing 100# 45: 0: # 0:45: # 0: 0:60 = 300# 15:15:20 Fertilizer Content

Soils & Nutrients Sources of Nitrogen Inorganic %N –Anhydrous NH 3 82% –Urea 46% –NH 4 NO 3 33% –(NH 4 ) 2 SO 4 20% –(NH 4 ) 2 HPO 4 20% –KNO 3 14% Organic %N –Dried blood 12% –Bat guano 12% –Fish meal 10% –Cottonseed meal 7% –Sludge 6% –Cow manure 2%

Soils & Nutrients Sources of Phosphorus & Potassium Phosphorus %P 1 –(NH 4 ) 2 HPO 4 54% –TSP 45% –Cottonseed meal 3% – 1 %P as P 2 O 5 Potassium%K 2 –KCl 50-60% –KNO 3 46% –Wood ashes4-10% –Seaweed4- 5% – 2 %K as K 2 O

Fertilizer Rules!/ adapted from Vir.Tech DON’T GUESS -- TEST! Virginia pine: maintain soil pH between 5.0 and 6.0 Eldarica pine: maintain soil pH between 6.5 and 7.5 Don’t 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.

Interpreting Soil Test Results--NM Flynn 2002

Tree Nutrition/ Hartman et al.2000

Put the Fertilizer where the Roots Are! RoT: The radius of root extension ~ height of tree

Tree age ApplicationSpringFall (years) Type oz/tree Band Band Broadcast Broadcast Nitrogen Rates for Virginia pine- NCSU

Tree age ApplicationSpringFall (years) Type oz/tree Band Band Broadcast Broadcast Nitrogen rates for Virginia pine- NCSU

Fertilizer Recommendations/ Vir.Tech Preplant or at planting: 1 oz/tree Year 1: 500 lb/ac Year 2: 2-3 oz/tree Year 3: 3-4 oz/tree Year 4: 4-5 oz/tree

Fertilizer Recommendations/ Vir.Tech Preplant or at planting: 1 oz/tree Year 1: 500 lb/ac Year 2: 2-3 oz/tree Year 3: 3-4 oz/tree Year 4: 4-5 oz/tree

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

Biomass Growth of Eldarica Pine / Sammis et al Above Ground Biomass (kg)

Nitrogen Uptake of Eldarica Pine / Sammis et al Above Ground Biomass (kg) 20 g N/tree 90 g N/tree Year-1Year-2Year-3 4 g N/tree

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-3&4 –3-4 applications (Spring-Fall) –Total N ~ 3.0 oz/tree (90 g)[uptake ~ 90 g/tree] Nitrogen Fertilizer Recommendations/

96 g N 72 g N 48 g N 24 g N Fertilizer Uptake Estimates- Eldarica pine-23 mo

Fertilizer Recommendations/-GroBag Root exploration is restricted Fertilize more like a container-grown tree You do not want much root development outside the bag Where do you fertilize Gro-Bag trees?

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

Foliar Nutrient Content/ Hartman et al.2000

Why is foliar testing important? Bondi, et al. OSU CES 2000

Fertilizer Recommendations Bondi, et al. OSU CES 2000