The Shadow KnowsPosted in: Farming By Elston Solberg June 1 2011
Who knows what evil lurks in the leaves of plants?
I apologize for bastardizing the title from the ancient radio show classic, “The Shadow,” but there is no doubt that… “The best thing you can put on your crop is your shadow.”
This statement is as true today as it was nearly 30 years ago when I first heard it AND it can be dramatically improved upon with the use of portable, low cost, easy to use, agronomic tools.
In a previous AgAdvance, we talked extensively about high tech shadows coming from satellites, planes, shoulder launched drones, Veris machines, yield maps and the like. This article will deal mostly with human shadows assisted by some of the warehouse of tools we have at our disposal that very few people are using today.
Most of us are sitting on huge yield potential (if we got the crop seeded) and big prices. Mother Nature has had a prolonged period of bitchy behavior, for many, that has resulted in saturated fields presenting more than a few problems, and lots of questions, this growing season.
Shadow Tools - Finding more yield, quality and understanding in 2011
Questions like . . .
“Can I really believe the goofy N (low and high) numbers in my spring soil tests?”
“Are my fall soil analyses still relevant given the incredibly wet winter/spring?”
“I’m new to Agri-Trend and my Agri-Coach hasn’t been able to sample my fields. How can I confidently grow a big crop without all the required data?”
“What yield potential am I really looking at on each of my fields?”
. . . and many more.
Some Tool-Assisted “Shadow Knows” Opportunities . . .
Scouting – Mother Nature tries many different ways all season long to prevent your crop from achieving full yield potential. Someone who’s properly trained needs to be casting a shadow on your field fairly regularly to watch for weeds, insects, nutrient levels, moisture levels, and weather impact . Whether you have the time and get yourself trained, or whether you work with an Agri-Coach, there are some great tools to amp up the value of the shadow casting.
Weather station(s) – are relatively cheap, and data acquisition and analysis is becoming easy these days. It is becoming more common to see farm based weather stations, and even multiple stations scattered around some farms. The data collected from these installations can greatly assist with in-season crop management decisions, as well as learning what impacts your yield from year to year. Cumulative heat units, wind speed, solar radiation, and precipitation are all factors that can mean the same formula that works great one season may not work very well the next time. Measuring, logging, and studying the data will reveal trends and result in better management decisions over time.
Soil Sampling After Seeding – this may seem strange BUT top corn growers do this all the time at the 6-8 leaf stage (PSNT – Pre-Sidedress Nitrate Test) AND there is extra valuable data obtained when done in conjunction with tissue sampling. For growers that have been sampling for a while, N to depth would be the nutrient to focus on. For new growers, a full analysis would help many in-crop decisions for this and future years, especially when combined with tissue tests.
Moisture probing – but, it’s wet, so what the heck am I talking about? Well there is a huge chunk of real estate out there that isn’t as wet as coffee row (and the media) portrays. There are large areas that have been in a cumulative moisture deficit for years now and have only recently received “normal” precipitation. If you look at the figure for the prairies, you will note that much of the map is yellow to brown which represents less than normal precipitation for the last 180 days. This is great for some areas and not so great for others. (see previous page)
The map is an indicator, but precipitation can be highly variable within very short distances, and even then it can run off or evaporate rather than soak in. What you really are concerned with is how much moisture is really in your field and available to your crop right now. A moisture probe is a very simple tool that tells a lot about how much yield potential a crop truly has, and can also double as “a poor mans penetrometer”.
Penetrometer – variability across a field can be caused by many different things. Compaction, whether naturally occurring or man-made, is a significant one. The penetrometer reveals what your crops root development is coming up against. If you find compaction, search further to determine if there is a pattern that might suggest wheel tracks as the cause, or a pattern related to field elevation, or if it’s general all over. There is at least 20,000,000 acres of ground that could benefit from this shadow-assisted tool. Many of those acres can be fixed once the cause is identified.
Leaf tissue analysis – there are many reasons to take tissue samples. Regular monitoring from soil sample locations gives additional information that is useful for this season’s crop, as well as future crops. Comparative sampling of good and poor areas helps isolate the issues contributing to crop variations. It’s always best to take soil samples from the same good and poor areas as well. A professional soil analysis is a great foundation to build a crop plan around, but a tissue analysis really complements that plan, especially in a year with so much
weather craziness and revenue potential. It can confirm strange results from the soil analysis, like we are seeing this season with N and P levels, or flag new issues to consider. I like to think of the tissue analysis as an annual physical, or a 51 point vehicle inspection. It uncovers things that may need fixing.
SPAD Meter – an optical device that clamps onto a leaf and measures chlorophyll content or “greenness”, which is highly correlated to N content. It’s light and portable, it reports results instantly, and it does not injure plant leaves. It is widely used in higher value crops (what crop is NOT high value this year) where check strips with very low and very high N amounts are used to calibrate the meter. Without calibration strips, a less accurate approach is to use the guideline charts available from some universities.
The SPAD meter does not indicate how much N is required to be optimum, but it does a good job of detecting slight changes or trends in plant health long before they’re visible to the naked eye. For in-season yield topper and protein manipulation, this can be one extremely valuable tool..
NDVI Meters - Normalized Difference Vegetation Index (NDVI) has been used for many years, usually by satellite, to measure crop vigor by correlating the “greenness” of crop growth with yield potential. Similar to SPAD, these units can “see” crop stress long before the human eye and long before irreversible yield losses are experienced. Sprayer mounted units like GreenSeeker are just starting to permeate our market as are hand held units that give accurate, rapid readings while crop scouting.
Portable pH and Salinity meters – trying to determine the cause of crop variability across a field should include the potential for pH and salinity variance, as they can often be the primary factors limiting a crops yield. A properly sampled soil analysis will give an accurate reading for pH and salinity, but it is an average of many sample locations reduced to one number. Handheld portable devices are ideal for trying to get an understanding of how the variances change by depth, and also between different areas of the field. Along with a yield map or satellite photo, this tool can be used as a good indicator of where soil samples should be pulled from.
Refractometer and Brix readings – was technology originally developed more than 100 years ago in the winemaking industry to measure the dissolved solids in a liquid, or more specifically the sugar content of a grape. Although there is enough data for grapes to make it a very reliable scientific tool, the brix reading of plant sap in crops like corn, wheat, barley, alfalfa, soybeans, and canola is not yet a science, it doesn’t replace the need for a good tissue analysis.
Bugs and diseases prey on stressed plants, they tend to avoid healthy plants. Healthy plants tend to have more sugar in their sap, and thus higher brix readings. A plants brix level will drop when it is exposed to stress such as heat, drought, flooding, low light, imbalanced fertility, etc.
The complexity is that there are so many variables in a field crop, and the brix readings can change very rapidly. A low brix reading indicates stress, but it could be as a result of cloud cover, and as soon as the sun appears, the stress is gone. Or it could be from a major potassium deficiency appearing as the surface soil dries and the roots search lower depths. The brix level wont differentiate for you, but if used frequently enough, and with a little experimentation, you will learn what triggers the brix levels and it will become a very valuable tool.
Knowing your plant is stressed before there is a visible symptom, and having the expertise to determine the cause of the stress and the possible solution, will pay off.
Digital GPS camera with macro function –several camera manufacturers have GPS built right in now, and many SmartPhones do as well. A picture is worth 1000 words, and being able to navigate right back to that precise spot again is priceless.
3G Tablet – the iPad and many other similar devices can connect you with the resources of the entire internet while sitting in your field. As well, you can take a photo and some jot notes and attach it right into a specific field record if you are using The Agri-Data Solution. A good visual reminder for later in the season.
These are but a few of the portable, relatively low cost, high tech tools that are shadow-enabled to help growers make better and better decisions.Talk to your Agri-Coach and come to Agri-Trend Agrology Summer Training August 9-11, in Regina, to get your own hands on experience with many of these tools.
I look forward to seeing you there!!
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