Agronomy Hacks 101 Notes

Agronomy Hacks 101

The Right Questions

• Instead of seeking answers, focus on identifying the right questions.

Disclaimer

• Some presentation content may be outside accepted wisdom.
• Use information cautiously, especially in exams.

Scientific Literature and Agricultural Practices

• Most scientific literature applies most of the time, but gains are in the exceptions.
• Benefits from some agricultural practices might not be included in existing trial measurements.
• Create your own data and use well-referenced datasets.
• Keep an open mind, but critically review alternate literature.
• Look for overlooked aspects in scientific conclusions or common practices.
• Paradigm shifts and significant gains come from the fringes.

Sweet Corn Program: CO₂ Impact from Nitrogen Inputs

• The Metagen program demonstrates a lower carbon footprint from nitrogen fertilizer per hectare per crop compared to previous programs.

Broadly Vigilant vs. Narrow-Focused Attention

• Iain McGilchrist is referenced
• There is a need for situational awareness.

Soilborne Plant Pathogens

• Managing diseases with macro- and microelements has been known for over 100 years that amending soil with lime reduces clubroot in turnip.
• Results may be inconsistent, working on some soils but not others.
• A soil chemist with a big-picture perspective is needed on the research team.

William Albert Albrecht

• William Albert Albrecht (1888-1974) was a chairman of the Department of Soils at the University of Missouri.
• He was an authority on the relation of soil fertility to human health.
• He observed a direct link between soil quality, food quality, and human health.
• He connected poor forage crops to ill health in livestock.
• He developed a formula for ideal ratios of cations in the soil: the Base Cation Saturation Ratio (BCSR).

Base Cation Saturation Ratio (BCSR)

• BCSR without Exchangeable Hydrogen at pH 5.5:
  • Ca: 55%
  • Mg: 37%
  • K: 5%
  • Na: 3%
  • Al: 0%
• BCSR with Exchangeable Hydrogen at pH 5.5:
  • Ca: 35%
  • Mg: 24%
  • K: 3%
  • Na: 2%
  • Al: 0%
  • Hydrogen: 36%
• CEC (Cation Exchange Capacity) increases as pH increases.

Calcium and Disease Score

• Calcium Formula 1 plotted against disease score:
  • Equation: y = -0.4264x + 1176.1
  • R^2 = 0.0802
• Calcium Formula 4 plotted against disease score.
• Other nutrient interactions are important.

Mineral Nutrition and Plant Disease

• Reference to the book "Mineral Nutrition and Plant Disease" edited by Lawrence E. Datnoff, Wade H. Elmer, and Don M. Huber.
• It is considered an "Outstanding Academic Title" by Choice magazine.
• Mineral nutrition plays a role during disease development.

Calcium, Boron, and Spotted Plants Interaction

• Figure 3: Calcium percentage formula 4, boron, and PS (percentage spotted plants) interaction.

Soil Solution Calcium and Exchangeable Calcium

• Equation: y = 0.3409x + 1.6474
• R^2 = 0.1048
• Relationship between soil solution calcium and exchangeable calcium.

Soil Solution Calcium and EC

• Equation: y = 5.3823x + 0.4169
• R^2 = 0.9485
• Soil solution calcium and EC (electrical conductivity).

EC and Soil Solution Calcium

• R^2 = 0.9854
• Relationship between EC and soil solution calcium in Grapes, Robinvale.

Soil Solution Calcium and Chloride

• Equation: y = 0.0412x + 2.6872
• R^2 = 0.7565
• A third ion, Chloride, is required for the best outcome.

Calcium, Boron, and Chloride Management

• Know the soil conditions.
• Monitor inputs, irrigation water, and soil test levels.
• Excess boron and/or chloride can harm plants.
• Measure, monitor, and adjust.

Plant Cell Wall Structure

• Reference to "Plant Nutrient Acquisition: New Perspectives" by N. AeJ. Arihara, K. Okada, A. Srinivasan.
• Pectin cross-linking, Glycan, Cellulose Microfibrils
• Boron and Calcium cross-linking at the RG-II region anchors the pectic network into cell walls.

Managing PPM and BCSR Targets

• Factors restricting the ability to manage ppm and BCSR targets for calcium, boron, and chloride:
  • Reward for effort relative to crop budget and problem scale.
  • Size of the CEC (Cation Exchange Capacity).
  • Uncontrollable inputs like Mg and Na in irrigation water.
  • Grower perception of reward from lifting cell wall integrity.
  • Misunderstanding of damaging chloride levels.

PPM Calculation

• Parts per million (ppm) represents one thousandth of a milliliter per liter of water or one milligram per kilogram of soil.
• To add 1 ppm to a hectare:
  • Depth of Impact: 0.25 m
  • SG of soil: 1.28 g/ml
  • 10,000 \, m^2 \times 0.25 \, m = 2500 \, m^3
  • 2500 \, m^3 \times 1.28 \frac{g}{ml} = 3200 \, tonnes
  • \frac{3200 \, tonnes}{1,000,000} = 3.2 \, kg
• 3. 2 kg is needed to change 1 ppm to a depth of 25 cm.

PPM to Meq/100g Conversion

• How PPM of each element translates to meq/100g or Cmole/Kg of charge depends on valency and mass.

Element PPM to Meq/100g or Cmole/Kg

• Calcium: 200
• Potassium: 391
• Magnesium: 121
• Sodium: 230
• Aluminium: 90
• Consider when trace cations are significant in terms of cation %.

Soil and Plant Biology and Disease Suppression (Part 2)

Metagen – Mode of Action

• Digestor contains labile and recalcitrant organic compounds that mimic plant signalling molecules
• Improving soil health can lead to:
  • Improved soil structure and WUE
  • Suppression of soil-borne diseases
  • Improved nutrient-use efficiency and organic matter processing
  • Yield gains
  • Improved stress tolerance

Elders Research Technical Research and Development - Kalyx run Tosari Site 2022 Harvest

• Average Yield Across Plots Kg/Ha
• LSD 421 kg/ha
• Control Yield
• Gain over control

NDVI Disease – Stripe Rust

• How? What was the mechanism?
• Equation: y = -0.003x + 17.899
• R^2 = 0.6927
• Wheat Yield V leaf Rust Rating

Lipoguard – Mode of Action

• Lipoguard is produced through fermentation of Bacillus velezensis LG1.
• It contains lipopeptides and other secondary metabolites.
• It is not an inoculant; active constituents are secondary metabolites.
  • Improved plant health
  • Suppression of plant pathogen growth
  • Induction of plant immune response (ISR)
    *Pending APVMA registration, Lipoguard is branded and marketed as a plant health product not a plant protection product.

Lipopeptides Identified

• Surfactins
• Pumilacidins
• Iturins
  *Fengycins

CROP SIZE AND SUGARCANE NITROGEN FERTILISER REQUIREMENTS: IS THERE A LINK?

• By PJ THORBURN1, JS BIGGS1, D SKOCAJ2, BL SCHROEDER3, J SEXTON4, YL EVERINGHAM4
• Aust Soc Sugar Cane Technol Vol 40 2018

Gross Margin vs. Nitrogen Application

• Sugar Price: $320/t, Interest Rate: 10%, Harvest and Levies: $6.61/t, Urea: $586.30/t
• Lsd(0.05) = 193

Research Articles Mentioned

• Associative nitrogen fixation (ANF) in switchgrass (Panicum virgatum) across a nitrogen input gradient
• Larger fertiliser 15N loss with increasing N rates in an intensive sugarcane system
• Interaction between soil and fertiliser nitrogen drives plant nitrogen uptake and nitrous oxide (NO) emissions in tropical sugarcane systems