Agronomist Notes

Once again my conversations this week covered the spectrum. I met with AccuFarm to discuss GPS options at the farm. Jim Halford, Conserva-Pak drill inventor, stopped by for a chat about seeding tools and to deliver a gazillion research papers on the topic. Lately, I’ve been having more discussions about growing farm businesses by sourcing outside capital.

In this issue of Beyond Agronomy News, we’ll begin by looking at a variable rate project that showed some impressive maturity results in 2009. Next, Mad Michael Eyers from South Australia will give us some more row loading nutrition examples. We’ll also look at a new way to measure how we maximize the amount of sunlight we capture and then wrap it up with fundamental and technical grain market news. Have a great week.

Agronomy

Tweaking N rates on VRT project improves crop maturity

In 2009, we completed our second year of variable rate fertilizer on a 217 acre field near the Beiseker, AB. This field has a long history of manure, has elevation changes upwards of 40 feet from north to south and sandy pockets that run NW to SE. The goal of using VRT in this field was to help even out maturity, reduce lodging, increase yield, and try to manage inputs better. In 2008, we were able to reduce fertilizer costs by just $4.40 an acre and gained a 14% yield advantage over neighboring fields. The net return in 2008 was $36.40 an acre for a $10.00 acre investment. Not bad! 

In 2009, a very dry, cool year with five inches of rain, we did not experience the same yield advantage with the VRT program but saw a remarkable difference in maturity. Out of six wheat fields totaling 1,900 acres, this VRT field was harvested seven days earlier than the rest! All the wheat acres were seeded within three days, May 14th to 16th, but this farm is over ironed and that’s another story. So, seeding date is not the reason for the difference in maturity. The difference in maturity was in the way we managed nitrogen.

To help explain how we managed nitrogen differently and what I believe caused the early maturity, I’ve included Table 1 that outlines each zone, acres, organic matter, N,P,K,S values and Table 2 that takes you through my nitrogen recommendations for each zone.

The biggest variable we gained control of using VRT and zone soil sampling was estimating nitrogen mineralization from organic matter. The amount of nitrogen being mineralized and made available varied significantly across this field because of the change in organic matter content across the landscape.  As you can see in Table 1, organic matter levels increased from 1.3% in Zone 1, lowest yielding, to 6.1% in Zone 6, highest yielding. Unfortunately, the highest yielding areas were always the last to mature and sometimes the first to fall over. Through zone soil sampling and VRT, we managed to improve our nitrogen recommendations and increase yield in 2008 and increase maturity in 2009.

Now, let me show you how I tweaked nitrogen rates to give the maturity benefits in 2009 and yield increases in 2008. In Table 2, you can see the yield target in bu/ac for each zone. Beside that is the total amount of N uptake required at each yield target. To calculate total nitrogen uptake, I’ve multiplied 2.5 lbs/N by the target yield. Next, I calculate how much nitrogen would be mineralized in each zone based on organic matter percentages. You’ll notice that my N mineralization rates are almost double the industry average at 8 to 15 lbs N per acre for each percentage of organic matter. Remember, this field is in a higher rainfall zone and has a history of manure that has altered the soil biology and nitrogen release rates over time. To get my N recommendation I simply subtract soil N and N mineralization numbers from the total N uptake for each yield target.
 
In the end, a difficult part of my job is trying to generate appropriate nitrogen recommendations when we’re pushing application rates to the upper limit of 90 to 120 lbs of N. A poor understanding of nitrogen mineralization can mean a flat crop and miserable harvest or too little can mean an average crop like the neighbors. Developing a zone map along with zone soil sampling even once on your fields may give you the additional information you need to make better decisions. We’ve managed to generate a 1.8 to 1 return on our VRT investment over the last two years with a 2.6 to 1 return on investment in 2008. I think we’re off to a great start. SL

Capturing solar energy through efficient leaf area index

We often debate about the right amount of seedbed utilization or row spacing in our cropping systems. What we’re really talking about is how to generate enough plants on an acre to harvest sunlight efficiently. The better we become at harvesting sunlight, the more efficient our plants become at producing grain. I believe we’ve been ignoring a way of measuring our crops ability to capture sunlight and thus should put to rest the seedbed utilization and row spacing debate. 

If a crop is going to capture all the sunlight that falls on its field, it must start with an adequate number of leaves arranged in a manner that intercepts as much sunlight as possible. This can be managed in a number of ways like nitrogen rate and timing, fungicides, seeding rates, row spacing and seedbed utilization to name a few. However, if we really want to measure our crops ability or limitation to capturing sunlight, we need to look at measuring leaf area index.

Leaf area index (LAI) is the ratio of leaf area in a crop canopy per unit of ground area. It is typically reported as the amount of leaf area covering 1 m2 of land. The size of that number is a good indication of your crops photosynthetic area, how much of the sun’s energy can be intercepted and absorbed to carry out photosynthesis. LAI is rated on a scale of 0 to 10. Zero being a bare field like you would find prior to emergence and 10 being a heavy barley crop after head emergence. Crop physiologists have agreed that we need enough leaf area to capture roughly 95% of the sun’s light. That level of interception, which allows 5% of sun light to penetrate down to the soil’s surface means that all of the good photons (blue and red) have been captured. That level of interception occurs at an LAI of about 3 in the case of plants like canola which have relatively horizontal leaf orientation. For cereals or plants with more erect leaf structures like wheat or barley, the optimum leaf area index is 5.

The picture to the right is a picture of canola at bolting taken near Okotoks in 2007 with an LAI of approximately 3.8, which is just above optimum. I used the BASF UK online LAI tool http://www.totaloilseedcare.co.uk/canopy-management/GAI/index.html that lets you upload crop photos to help determine LAI. It’s not a precision tool but it will get you close.

Understanding how to attain ideal leaf area indexes will help us avoid overly thick vegetative canopies that lead to inefficient use of sunlight and water, avoid thin canopies that waste sunlight and do not fully utilize available water. It’s not about row spacing or seedbed utilization. It’s about managing a crop canopy to capture sunlight as efficiently as possible. SL

Source: http://www.soils1.cses.vt.edu/djp/4344hp/4344handout/unit2/photocanopy.pdf
Source: http://www.hgca.com/document.aspx?fn=load&media_id=1045&publicationId=680
Source: http://www.sfs.org.au/resources/Hi%20Grain%20-%20canopy.pdf

Row loading calcium to improve sulphur uptake in sodic and low pH soils

By Michael Eyres, Injekta Pty Ltd, South Australia

One really interesting insight into cropping has been our greater understanding of the role of calcium and how it relates to the uptake of other nutrients. Steve highlighted several weeks ago the importance of calcium (even in high calcium soils) for development of plant auxins and thus accelerated early vigour in plants. That is absolutely correct for many soil types. Here in Australia, in more sodic and acidic soils, the effect of calcium in solution has been to sequester the sodium and tie up the soluble aluminum that comes into solution as the soil wets up and acid fertilizer granules are added to the furrow.

An example is canola. Canola loves sulphur and requires it to initiate and complete all stages in its life cycle in effort to build seed numbers and fill them with oil! If you have higher levels of soluble aluminum in your soil it will act to inhibit sulphur uptake as aluminum ties up sulphur to form aluminum sulphate, which is not plant available. However, soluble calcium will alleviate this problem at very low rates and low cost in furrow. We have used a liquid calcium source with approx 12,000ppm per litre as a liquid calcium carboxylate.

A canola trial done two years ago in Esperance, Western Australia on acidic soil proved this point. The chart you see here shows, in Canadian terms, a 2 bu/ac difference each time we added a liquid calcium carboxylate in the furrow at seeding. The average plot yielded 26 bu/ac and the treatment plots yielded 8% higher.  

Steve’s note: The reason aluminum toxicity is rarely discussed in Western Canada is because we tend to have neutral pH’s with moderate to high levels of calcium to buffer out the effects of soluble aluminum. Several fields I manage have soil pH’s touching on 5.5 to 5.8 in the top six inches. The continued application of acidifying fertilizers may bring artificially bring on aluminum toxicity. Thankfully, we have a solution like the addition of calcium or gypsum in the furrow at seeding, but it’s something we should be aware of going forward. SL

Market News

Fundamental Analysis

Technical Analysis

Canola: March futures. Short term trend is up. The long term trend is down.
HRS Wheat: March futures. Short term trend is up. Long term trend is down.
Corn: March futures. Short term trend is up. Long term trend is down.
Soybeans: March futures. Short term trend is choppy. Long term trend is down.
Canadian Dollar: March futures. Long and short term trends are up.
US Dollar Index: March futures. Short and long term trends are up. 
Crude Oil: March futures. Long term trend is up. Short term trend is down.