AgAlerts 2009 From Griggs County
By John Swenson, Griggs County Extension Agent

                                                                                                                        NDSU Crop Pest Reports

Issue #4, May 22, 2009

Fertilizer, Value of Residues

    This past winter, Dave Franzen, NDSU Extension Soils Specialist, gave a video-conference on "Fertilizer Value of Residues".  Some reasons for a renewed interest in residues is fertilizer prices, ethanol production and livestock feeds.  The following is a summary of his presentation.
    Increase in fertilizer prices has caused a greater interest in "what is the amount of nutrients that are in the remaining residues".  A ton of wheat straw yields 13 lb of nitrogen, 3.5 lb of phosphorus and 23 lb of potassium.  A ton of corn stalks yields 22 lb of nitrogen, 6 lb of phosphorus and 32 lb of potassium.  Some factors to consider is the condition, maturity and grain yield in relation to residue will make a difference in nutrients removed.  Residue from corn that does not make grain can contain over 100 lb of nitrogen, 40 lb of phosphorus and 100 lb of potassium.  Potassium in corn residue depends on how long the residue remains in the field.  Potassium can leach out of dead plant tissues.  Nitrogen and phosphorus do not, unless substantial nitrogen is stored in plant cells as nitrate.  Corn residue contains more nitrogen in the lower stalk than the upper stalk.  Cobs contain very low levels of N, P or K.  The nutrient breakdown in a corn plant is as follows:  Corn grain - 1.3% N, 0.26% P and 0.35% K.  Corn stover - 0.5% N, 0.1% P and 0.9% K.  Corn cobs - 0.33% N, 0.03% P and 0.45% K.  In wheat, a ton of non-grain producing residue can contain 80 lb of nitrogen, 30 lb of phosphorus and 45 lb of potassium.  
    The release of nutrients will vary in different production systems.  Fresh residues may release 1/3 of their N the first year in conventional tillage systems.  In No-till systems, nutrient release is slower and perhaps only 20% N is released in the first year.  NDSU soils lab will include residue decomposition into fertilizer recommendations.  Residues with high N such as annual or perennial legumes are the basis of "previous crop N credit.
    Burning residue will remove nitrogen and sulfur in the smoke but phosphorus and potassium will remain.

Weed Seed Production

    Weeds are a constant yield inhibitor in crop production.  The amount of seed produced will vary by the plant population and the amount of seed a weed specie can produce.  Many weed seeds have hard seed coats, do not germinate readily and may remain alive in the soil for many years.  Seeds of wild mustard, curly dock and redroot pigweed have germinated after being buried in the ground for 50 years but grass seeds did not survive so well.  The following table will show the possible seed production of common weeds in Griggs County.

Seed Production of Individual Weeds
Plant Number Seeds per Plant Weight in Grams per 1000 Number in 1 ounce
Foxtail Barley 2420 1.1 25,800
Barnyardgrass 71600 1.4 20,200
Wild Buckwheat 11,900 7.0 4000
Dandelion 15,000 0.5 56,700
Green Foxtail 34,000 1.5 18,900
Yellow Foxtail 6,420 4.2 6,700
Common Lambquarters 72,450 0.7 40,000
Marshelder 82,150 1.2 23,600
Wild Mustard 2,700 1.9 15,000
Wild Oat 250 17.5 1,600
Field Pennycress 7,040 0.8 35,400
Redroot Pigweed 117,400 0.38 74,600
Common Ragweed 3,380 3.9 7,200
Shepherdspurse 38,500 0.1 238,500
Perennial Sowthistle 
(one stem)		 9,750 0..4 70,500
Leafy Spurge
(one stem)		 140 3.5 8,100
Canada Thistle
(one stem)		 680 1.6 17,700
Biennial Wormwood 1,075,000 0.07 375,000
The above table, The Number and Weight of Seeds Produced by Weeds by O. A. Stevens, is compiled form a more detailed report on North Dakota weed seeds in the American Journal of Botany for November, 1932.

Nutrition Facts for Spring Wheat Production

Nitrogen (N)
  • 2.0 to 2.5 lb/bu is needed.  example a 40bu yield estimate will require 80 to 100 lbs of N.
  • About 80% of N uptake occurs before heading.
  • Necessary for photosynthesis.
  • Adequate supplies increase water efficiency.
  • Uptake varies among varieties & environment.
 Phosphate (P2O5)
  • Requires approximately 0.6 to 0.7 lb/bu.
  • As much as 70% of P uptake occurs before heading.
  • Essential for vigorous root and shoot growth.
  • Increases tillering and grain heads per acre.
  • Necessary for energy storage and transfer in plants.
  • Immobile in soil.
  • Advances maturity, lowers grain moisture at harvest.
  • Improves input efficiency, especially N.
Potash (K2O)
  • Requirements for K are approximately equal to N.
  • About 85% of K uptake occurs before heading.
  • More than 2 lb/a taken up each day during peak demand.
  • Helps plants tolerate moisture stress, lowers incidence of disease and lodging.
  • Increases water use efficiency.
 Sulfur (S)
  • A high-yielding crop requires about 0.25 lb/bu.
  • Essential for chlorophyll formation.
  • Can increase N and P use efficiency.
Magnesium (Mg)
  • A high yielding crop will take up 20 lb/a or more.
  • Involved in photosynthesis.
  • A part of chlorophyll.
 Chloride (Cl)
  • Involved in the photosynthetic process.
  • Helps plants retain moisture under stress conditions.
  • Helps lower incidence of foliar and root fungal diseases, especially when shoot Cl concentrations are below 0.15%.
  • Responsiveness to Cl differs among varieties.
Micronutrients
  • Most common deficiencies are from copper (Cu), Maganese (Mn), and zinc (Zn).
  • Deficiencies usually are visible by tillering.
  • Visible deficiency symptoms frequently occur too late for corrective measures.
  • High availablility of P can limit uptake of Cu, Mn and Zn.


    

NDSU is an equal opportunity institution

Please Contact Our Office For Additional Information
E-mail: john.swenson@ndsu.edu
Go to the 2008 AgAlert Index Page