January 15, 2013

Agronomists Notes

Hello Reader,

For the last week I’ve been buried in yield maps, grid sample maps, zone maps and statistical correlation tables while trying to uncover the lost arc in the world of nutrients and yield. I’ve contemplated using a tensor bandage to hold my head together to avoid explosion. Had I been wearing a hat, it may have caught on fire a few times but I digress.

I’ve also been busy getting presentations prepared for February when I’ll be speaking in South Australia at a no-till conference and then in Queensland at the inaugural International Controlled Traffic Farming conference. I’m also making a few mental notes for my presentation at the Contemporary Scholars Conference in Niagara Falls for the 2013 group of international Nuffield Scholars. The best $7.00 I ever spent was today when I found a website for unlocking cell phones!

Things are quiet on the farm front with most fertilizer deals done and the rest waiting it out. Farm-grown seed is being tested and cleaned, canola seed is bought and land rental deals are being renegotiated after two months of coffee shop talk and landlords wanting their fair share, whatever that may be.

This week we’ll review how statistics has opened my eyes to an underutilized measure of potassium availability called the K/Mg ratio. Next, Ray Garnett from Agro-Climatic Consulting predicts shorter growing seasons for the Canadian Prairies until 2020. Buckle up! Last, we’ll look into sulphur strategies that improve availability and efficiency. We’ll end with technical grain market news.

Have a great week!

Statistics uncovers K/Mg as a significant driver in yield potential

K/Mg ratio: the under utilized potassium fertility measure

I’ve been working on a research project that uses statistical analysis to measure spatial data. Our purpose is to establish what nutrients and soil quality parameters drive or drag yield in each field. We do this by overlaying 1-5 acre grid soil sample data on top of yield data and running correlations. So far, the correlations have uncovered some surprising results, one being potassium to magnesium (K/Mg) ratios.

K/Mg is the ratio of potassium to magnesium in the soil and can be measured by dividing the K% by Mg% on a base saturation level. The reason this ratio is important is because it determines the amount of potassium and magnesium available to the plant. An imbalance either way can create a potassium or magnesium deficiency, even when soil tests suggest optimum levels in the soil. What’s surprising is that potassium and magnesium individually did not correlate to yield very often yet the yet K/Mg ratio did.

For the stats geeks out there, we did a Pearson’s Correlation Coefficient with three fields equaling 400 acres with soil samples taken on 1-acre grids. The yield maps were cleaned up to remove the outliers and correlations run.
The R-values for K/Mg ratio were 0.23, -0.24, 0.19 respectively with p values of .02, .01 and .03 suggesting a 95% significance level.

The image you see above is a yield map of barley zoomed into a 20-acre area with K/Mg ratios overlaid on top, each one representing 1ac. The yield in the dark blue areas ranged from 115-120 bu/ac versus the red and pink areas, which ranged from 75-80 and 80-85 bu/ac, respectively. You can see the dark blue highest yielding areas have a K/Mg range of 0.43 to 0.50 where the lowest yielding red and pink areas are below 0.20 or above 0.81. Looking across the field, all the highest yielding areas have a sweet spot between 0.43 and 0.54.

The only soil lab calculating K/Mg ratios for Western Canada is A & L Labs. A & L suggests an optimum K/Mg ratio of 0.25 to 0.35 for Western Canadian crops except for potatoes, which recommends a range between 0.30 to 0.40. There is very little research on the proper ratio and, as I just pointed out, there may be a wider range or one that is different for each field. I did manage to find some information on the International Plant Nutrition Institute (IPNI) website that found the K/Mg ratio significant in tomato production and a better measure of potassium uptake than just potassium alone.

In the end, a combination of the sufficiency approach to potassium fertilizer along with an indicator like K/Mg ratio may improve your chances of uncovering a potassium deficiency. Perhaps those high potassium soils you thought were sufficient may improve with the addition of potassium fertilizer. I know it has me rethinking the way I produce potassium recommendations. SL

For information on the potassium sufficiency approach go here.

For information on K/Mg ratios go here.

To see the IPNI research go here.

Shorter growing seasons predicted for Prairie producers

A few years ago Beyond Agronomy sponsored leading edge climate prediction research for the Canadian Prairies by Ray Garnett of Agro Climatic Consulting. Ray has now published the results of his study and the model predicts shorter growing seasons for Prairie producers out to 2020. The model uses a number of unique indices including sun spot activity.

“Solar activity between now and September of 2013 will be of considerable interest as well as significance as there is increasing evidence that a Dalton Minimum is shaping up which brought cooler than average global temperatures between 1790 and 1830. The deepest solar minimum in 95 years occurred in 2009. Had it not been for a miraculously warm, dry September that year it is doubtful the wheat and canola crops would have been harvested. Solheim et al 2012 are forecasting a .9 C. cooling in Northern Hemisphere temperatures during solar cycle 24 between 2010 and 2020 further suggesting shorter growing seasons for prairie grain producers.”

[To view his research on powerpoint, go here.]

Shorter growing seasons. I’d day it’s time to focus on all the little things that we ignore that hinder maturity, such as sloppy seeding techniques, poor residue management, poor plant densities, wheel tracks, the list goes on. Don’t get caught out in the frost. SL

The Ray Garnett Climate and Crop Letter will help you track key drivers of prairie and global climate. It’s published 23 times a year at a cost of $195. A three-month subscription is available $65. To subscribe, email admin@canadagrain.com with your email address, visit their website or telephone 1-204-942-1459.

Sulphur strategies to maximize availability & efficiency

Sulphur is an essential nutrient required for plant growth and survival. It is a structural component of proteins and enzymes and aids in the production of chlorophyll. Plants also use sulphur to convert inorganic nitrogen to protein and for nodule formation in legumes. Sulphur has also been linked to greater nitrogen recovery when nitrogen is applied at high rates.

Sulphur is typically required in the crops early lifecycle, so having the correct form of sulphur available is important. The release from organic matter is quite small (2-3 lbs/ % organic matter) and typically happens later in the growing season. Without adequate fertilization, sulphur-demanding crops could become deficient especially on sandy and low organic matter soils.

Sulphate versus elemental sulphur

There are benefits of incorporating an elemental form into a fertility program because of high analysis or homogenous products also containing phosphate and nitrogen sources. A fertility program strictly using elemental sulphur requires forward planning and perhaps an additional application to ensure that adequate plant available sulphur is present at early growth stages. Elemental sulphur is not plant available until it’s oxidized and broken down by bacteria into sulphate form. Using ammonium sulphate provides plant available sulphate but is bulky and can increase fertilizer blend rates. It can also create storage concerns with bridging and lumping.

Strategies for sulphur fertilization

Match sulphur additions to uptake and removal calculations.
Consider a “supply and build” strategy based on uptake, texture, and organic matter content of the soil.
Apply higher rates in years that higher demanding crops are grown and apply a maintenance level in other years to keep the sulphur supply charged.
Apply a high application rate of elemental sulphur once every 3-4 years. Since elemental sulphur releases sulphate over time, it is a way of improving soil supply and lower risk of loss.
Increase soil organic matter with applications of manure, compost, or avoid baling straw.

How much sulphur does a 4-year rotation require?
Crop Canola Barley Peas Wheat Total Uptake (Removal)

Yield bu/ac 50 80 60 60

Sulphur uptake 25 12 13 12 62 (35)

In the table above, the uptake of sulphur over 4 years is approximately 62 pounds of actual sulphate and a removal of 35 pounds providing the straw and trash are left on the land.

Products on the market

Ammonium Sulfate (21-0-0-24) contains 24% sulphate
Mono-Ammonium Phosphate Sulphate (16-20-0-13) www.simplot.com contains 13% sulphate
Tiger 90 Sulphur (0-0-0-90) www.tigersul.com contains 90% elemental sulphur
Tiger 50 Sulphur/Sulphate (0-0-0-50) www.tigersul.com contains 28.57% sulphate and 71.43% elemental sulphur
MicroEssential S15 (13-33-0-15) www.microessentials.com contains 50% sulphate and 50% elemental sulphur

Here are a few scenarios to help guide you through the product and rate selection process:

Scenario 1: Ammonium Sulphate (21-0-0-24) based on 100-25-0-25 blend
Application rate: 311 lbs/ac
Cost: $77.00 acre

Scenario 2: MicoEssential S15 (13-33-0-25) with additional AMS based on 100-25-0-25 blend
Application rate: 303 lbs/ac
Cost: $80.00 acre

Scenario 3: Mono-Ammonium Phosphate Sulphate (16-20-0-13) with additional AMS based on 100-25-0-25 blend
Application rate: 319 lbs/ac
Cost: $85.00 acre

Scenario 4: Tiger 50 (0-0-0-50) based on 100-25-0-20 blend
Application Rate: 304 lbs/ac
Cost: $79.00 acre

From the above scenarios, we can see that application rates and costs are not that much different. However, S15 with a blend of AMS for tanks that are 400 bu and larger, you could increase the number of acres per fill by 10 acres or more.

Sulphur fertilization shouldn’t be overlooked. There are several application strategies to consider for maximizing crop availability and minimizing losses. Choosing the right form for the situation is important for efficiency of application and uptake. Daryl Chubb

International Controlled Traffic Farming Conference

Toowoomba, QLD, Australia, Feb 25-27, 2013

If you’re looking to travel to a warm place, see the latest in controlled traffic farming research and write the cost off as an educational expense, I suggest you consider attending this conference in Toowoomba, Queensland, Australia.

There are three action-packed days of research and farm visits planned, exploring the benefits, challenges and progress made in CTF over the last decade. Yours truly will be presenting which is another good reason to book now so we can have a visit 7,848 miles down under.

For conference details, go here