The Cropwalker - Volume 4 Issue 33
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Weather In general crops are average or a bit ahead. The stage of maturity may not be reflected by CHUs. To establish our CHU system, CHUs were collected and calculated over about a 30-year period. During this time the amount of sunlight was averaged. It takes heat and sunlight to advance corn. This year I believe we have lots of heat and not the average amount of sunlight. This means that corn is not quite as advanced as CHUs suggest. And you need moisture to take full advantage of the sunlight. This year the way the rain came in some areas, fields of both corn and soybeans have a shallow root system. A side comment is that CHUs level out at 30 degrees C. So, days above 30 degrees count for the same amount of CHUs as days at 30. Low night time temperatures give fewer CHUs than higher nighttime temperatures. For instance, a high of 29 and low of 21 collects 31 CHUs. A high of 29 and low of 11 collects 22 CHUs. The corn plant lays down lignin during August. This year with less than normal sunlight means corn plants probably laid down less lignin than normal. Standability may be affected. Corn is moving along rapidly. Expect to see silage start at end of this week or start of next. Don’t let it get too dry. Comments that there are fewer than normal kernels per cob. (Could be sunlight/nitrogen related) I am not worried. Yield is made up of kernel number as well as kernel weight. (Weight of a thousand kernels – TKW) I think we will see heavier TKW this year. Soybeans – more fields are turning colour, at least on the knolls. Bodes well for an early harvest. This will help get wheat planted early. Some of the newer wheat varieties are near sold out. If you want to try some new genetics get your order in. Cover crops Starting to see rust in oats cover crops. We like to delay spraying for rust until you have a lot of leaves. Ideally wait until flag leaf. However, if rust gets really heavy early you will not have much plant by the time flag leaves appear. Check all oats cover crops and spray if you see rust. You may have to spray again in 2 weeks. Summer seeded alfalfa check for volunteer wheat. Picture below shows a field that was not sprayed with glyphosate to control volunteer wheat before alfalfa was planted. It has to be sprayed NOW. If you have volunteer wheat this heavy you must control it even if it means killing the grass. In this case, use Assure (or its generic equivalent) and then reseed grasses. Established alfalfa tremendous yields. The weather this past two weeks is causing alfalfa to lodge. Like in a good first cut. No sun and lots of moisture means alfalfa will go down. Also means it will take longer to dry down once cut. One reader commented that he thinks he had 4 first cuts this year. Great yields. This means the crop removed more nutrients than most years. If you want a good yield next year, put on fertilizer this year.
Top things to do this week
1. If taking them for feed, check oats for rust. While it does not impact feed quality, it does impact palatability and yield.
2. Check cover crops for weeds and control if required.
3. Spray fence lines and other areas for unwanted brush. September is the best time to do it. We used to use diesel fuel and Estaprop/Dichlorprop (this is still a registered tank mix, see label)
4. Check summer seeded forages for volunteer wheat.
5. Call on your neighbours to see how they are doing. There is a lot of stress now.
What should I put on forages in the fall?
We have written about this quite a bit but continue to get questions. And since most are limited on how much $$ they have available, here is a few points; In the absence of a soil test. First few dollars should go to potash. This should likely be in the range of 60 to 120 actual K2O/ac. The next few dollars should go towards phosphorus. This should likely be in the range of 30 to 60 actual P2O5. The final dollars could go towards boron, up to 1 lb. actual B per acre. But the boron recommendation is very much soil type and forage species depended. Don’t wait on getting this applied, as you will need the plant to take it up prior to going dormant. Finally, the preferred option is to make recommendations on soil tests, to ensure you are getting value on your fertilizer dollars.
Boron – Coles Notes
If there is one micronutrient, I feel that I have spent considerable amount of time researching, it is Boron. The Coles notes of what you need to know.
1) It is taken up with mass flow, meaning water, into the plant. For the plant to take it up, it needs to be freely available in soil water. Once in the plant, it is not mobile and is locked into plant material.
2) To be freely available in water, it is mineralized mainly from soil organic matter. When in dry conditions where water is not available in parts of fields with high soil organic matter, it will stop mineralizing. Therefore, you see boron deficiency showing up in dry weather on susceptible crops, plus soil water is being pulled from deeper in the soil profile, where there is little boron to mineralize.
3) Not all crops respond to boron. But because we have not been using it as part of the fertilizer program, we are starting to see it on crops that are usually considered less responsive, like corn and soybeans.
4) In most manure tests I have come across. there is very little boron.
5) Boron availability can be impacted by liming, especially on soils over 6.5 pH, due to complexing with Al (OH)3.
6) In soils with high calcium availability, plants can tolerate high B availability.
7) Sandy soils, especially those with coarse subsoils, are the most responsive to B. Soils with clay textures or clay subsoils, tend to have lower responses to B.
8) Relative to other nutrients, boron can be toxic to plant roots are low application rates, which is typically why broadcast or foliar applications are favored on most crops, and annual applications of low rates should be made.
9) Plant species can have genetic variability in response to boron due to a single recessive gene, for example, in tomato varieties and corn hybrids.
Fertilizer - Actual vs Analysis
When we talk about actual, we are referring to the amount of nutrients being applied, or how much plant food has been applied to the soil. The plant will then take up a percentage of this. What happens to the remainder will depend on the nutrient.
When we talk about analysis, we are referring the how much of the fertilizer or material weight contains each nutrient. This is always written as N-P2O5-K2O, as required by the Fertilizer Act.
The amount of material applied, of a particular analysis or product, determines how much “actual” plant food you have applied.
Why is this important? In some situations, the producer may only have access to set blends. Let’s take 19-19-19 and 6-24-24 for example.
If the soil test suggests they require 60 units of P2O5 and 60 units of K2o per acre. Then they would have to apply 315 lbs./ac of 19-19-19 or 250 lbs./ac of 6-24-24. But the 19-19-19 would also provide you with 60 units of N, whereas the 6-24-24 would have 15 units of N/acre. If the crop didn’t require any nitrogen, then you be applying 45 units of N for no reason. While it is preferable to do custom blends to get the right ratio of nutrients, the crop person making the recs should easily be able to find and recommend a standard blend analysis in situations where they occur.
Winter wheat variety selection – Some thoughts on variety comparisons from the OCC trials. When you compare varieties across the trials, the trials with an “A” indicate intensive management which is two fungicide applications. I think the index from 2-3 years is more meaningful than from 5 years. An index compares a variety to the other varieties. The lower yielding varieties will be removed. In 5 year, trials you would expect a variety to index higher since it is being compared to lower yielding varieties which are not in the 2–3-year comparison. These trials are maybe run under different management than you use (tillage, different soil types, fertility etc.), so your experience will trump these trials. But you really should be trying at least one new variety under your management system.
Corn for Silage – this table shows that corn at early dent is around 75% moisture. Black layer is 55-65% moisture. For some bunk silos you want 65-75%. The exact % depends on size of bunker, speed of fill and how well you can pack it. Main point is it is about 30 days from early dent to black layer. If you are making silage now is a good time to start watching how your corn is maturing. There will be differences in dry down from hybrid to hybrid, so the table is an approximate rule of thumb.
Pre-Harvest on Alfalfa
Some years fields that had been burnt off later in the season do not have proper control due to lack of growing degree days and the size of alfalfa at the time of termination. My preference would be to terminate the alfalfa pre-harvest. This gives a better kill due to more top-growth. This also allows you to spread manure or do some tillage immediately following harvest.
From the Roundup Transorb HC Label;
For forage crops, apply this product at 1.67 to 3.33 liters per hectare (0.67 to 1.33 L/ac) 3 to 7 days prior to the last cut before rotation or forage renovation. Apply only during the period 7 to 14 days (or 3 to 7 days for forage applications) before harvest to ensure best weed control and to maximize harvest management benefits. Earlier application may reduce crop yield and/or quality, and may lead to excess glyphosate residues in the crop.
Majority of fields I have been in are either just coming into R6 or just past R6.
R6 = Full seed at top of the plant
R7 = 1 Brown pod on them stem
R8 = full maturity
Pre-Harvest on Soybeans/Edible Beans
Really only two options. And the end user has the ultimate say. (Check before you spray) Glyphosate at 0.67 L/ac, glyphosate @ 0.67 L/ac plus Eragon at 30 to 60 mL/ac plus Merge @ 400 mL/ac.
Eragon – When, Where and How Much?
Eragon is a desiccant. (Glyphosate is not a desiccant) The Eragon use rate of 1X rate is 29 ml/ac. Use the 1X rate for desiccation. Use the 2X rate before winter wheat for desiccation and to provide residue control of fleabane and chickweed. Always use Merge and glyphosate. The rate of glyphosate is dependent on weeds present. Watch glyphosate rate and days before harvest if spraying pre-harvest. If you have a field mainly with perennial weeds, such as dandelion or sow-thistle, I recommend only using glyphosate and leaving out the Eragon for better translocation.
My soil tests came back with lower pH than expected, should I start applying lime to stay ahead of it?
Based upon my conversation with Mike Folkard @ A&L Labs, I would hold off on backing up the lime truck. Some of what we are seeing is weather/seasonality related and has to do with how much acidity is showing up in the soil at the time of year from the cereal crops we have just pulled off. If you are very concerned with the lab results and have dropped GPS points/coordinates. Go back to the areas in 6-8 weeks and pull another soil test from those points. Just request the most basic package (at a minimum pH and buffer pH), you can then see if it comes back as acidic as the last test. If it is still acidic, you may need to start applying lime on those fields. If you have a lower pH of what was 8.2 on testing 3 years to 7.6 this round, no lime is required. If you see it drop from 6.9 to 6.4 in 3-years, it is maybe time to consider liming.
If you haven’t taken high school chemistry in a while, 7 is a neutral pH, below 7 is acid, and above 7 is basic (alkaline). pH is a logarithmic scale at a factor of 10. Meaning a pH of 6 has 10 times more H+ ions than 7, and a pH of 5 with 100 times more H+ in the soil. The issue with acidic soils, is it can reduce nutrient use efficiency, and cause reduced plant growth in many crop species. Or it can make some nutrients more available to the point they are toxic.
When adjusting soil pH, you are trying to counter act the acidity in the soil. The soil lab estimates the amount of acidity in the soil by running a buffer pH. The pH listed on the soil test is from a water extraction, with the buffer pH completed using buffering agent. The buffer pH is only used to determine the amount of lime you require to reach the target soil pH.
-Evaluating source materials
The only liming materials that can raise soil pH, are those that contain carbonate. The calcium or magnesium in the material is simply along for the ride, with the carbonate portion neutralizing any soil acidity. For this reason, calcium products like Gypsum (calcium sulphate), will not adjust soil pH.
If you have low magnesium levels, you should be using dolomitic lime.
-How much to put on, when
My preference is to apply lime in the fall, to allow the liming material to neutralize soil acidity, and provide time to get the work done without having to worry about soil compaction or holding up planting/seeding. For soils in tough shape with ultra-low pH, you may want to make multiple application over the period of a couple of years.
As far as rates, the chart below is a starting point. This based upon an AgIndex (neutralizing value) of 75. Ideally the material has been tested and you will be able to determine if you need more or less material based upon the materials AgIndex.
Publication 811 - Agronomy Guide to Field Crops
Chapter 9 - Soil Fertility
Had several questions on (Sudden Death syndrome) SDS, if you have pockets of fields that are dying prematurely, check for SDS (and SCN!)
Integrated Weed Management (IWM)
A great tweet this week by Bob Hartzler on IWM. This is an excellent follow up to last week’s article on integrated weed management, and why you need to diversify how you manage weeds.
Largest yield barley crop – ever – in the world!
Was grown this year in the UK by Tim Lamyman, a multiple winner of the Yield Enhancement Network awards for cereals and oilseeds (5 cereal gold medals in 8 years). How has he done it? He treats his barley crop like solar panels. This means selecting barley that allows light into the canopy amongst other factors.
Take a listen below… a few good pointers that are applicable to wheat.
World record barley crop grown in the UK - Victorian Country Hour - ABC Radio
A UK farmer has set a new world record for barley yields after treating his crop like solar panels.
What are these SWAT Maps you are talking about, and when should I be using it?
SWAT maps does not involve the local police force. It is an acronym for Soil, Water and Topography maps. It is a zoning process to group similar response areas in a field together. This is done using pre-defined zones to manage the field and optimal apply inputs. By pre-defining how areas of the field behave, you are able to target soil sampling and specific inputs to those areas to better manage field variability.
When should you use this soil sampling/crop management process? When you have, or will have, the ability to apply and measure inputs using variable rate capabilities in the field. For a YouTube video on the process, please see the one below I completed with Lambton Soil and Crop.
"I like a teacher who gives you something to take home to think about besides homework."
– Lily Tomlin