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March 1, 2013 – This series focuses on tools and approaches for attaining higher corn grain yields.
In the previous tips this winter, guidance was given for planning and analyzing on-farm research trials. In this tip, guidance is given for testing two different management approaches: i) a higher yield system and ii) current farmer practice.
This experiment should be planned to run at least three to five years. An example layout using six replications is below:
Notice how the two treatments are randomized within each replication, or block.
Each year, the same treatments should be applied to the same locations. In other words, this same plot plan should be used every year in the same field location. This allows the cumulative effects of the different management practices to be tested over time. For instance, in the first year, not much difference may exist between the two treatments, but after five years, the two management practices may produce enough differences in the soil system to create statistically significant results.
See the earlier tip on using the free, online AGSTATS 02 tool (http://pnwsteep.wsu.edu/agstatsweb/index.html) to quickly and easily determine statistical differences.
February 20, 2013 – This series focuses on tools and approaches for attaining higher corn grain yields.
As discussed in the previous tip, many high yield farmers conduct trials on their own fields. However, very few ever analyze their results statistically. Statistical analysis determines whether or not true differences occurred among treatments.
An online tool exists for running statistical analyses for the types of experiments that are often conducted on farmers’ fields. The tool, AGSTATS 02, can be found at: http://pnwsteep.wsu.edu/agstatsweb/index.html. This tool is the result of a collaborative effort by scientists at Oregon State University, Washington State University, and University of Idaho. The following eight steps will get you started:
- Create a new account. It is free.
- Select “Create a new dataset.”
- Enter the number of treatments per block and the number of blocks
- Select “Randomized Complete Block Design”
- Select “5% level of significance”
- Input yield data for each treatment within each block
- Click “Analyze.”
- At the bottom of the window, look at the little table that has two columns: i) Treatment Name and ii) Mean. Look at the letters to the right of the averages (means). These will be “A, B, …..” If two rows share at least one letter, then the averages are not statistically different. If any two rows have completely different letters, then the averages are statistically different.
If you already have yield data for each treatment, this statistical analysis can be done in less than five minutes and you’ll have a real insight into whether or not the differences in the treatments were great enough to overcome the background noise of yield variability in the field.
February 10, 2013 – This series focuses on tools and approaches for attaining higher corn grain yields.
Many high-yield farmers conduct small experiments within fields. These trials help them test new ideas and products. A common experiment is comparing hybrids or varieties.
There are some “rules of the road” when it comes to running experiments on the farm. Some key guidelines are:
- Replicate. Let’s say you’re wanting to test three hybrids. Plant all three in side-by-side strips (Block 1) then move to a new area and plant all three again (Block 2) and so on until you have at least four blocks or replicates. The following diagram illustrates the concept:
- Randomize. In the diagram above, Hybrid A, B, and C are not always planted in that order within each block. Mixing up the order of treatments helps eliminate chances that one hybrid always falls on better or worse areas of the field.
- Keep it simple. Don’t try to compare too many things at once. Compare two to four things at most. It is better to test fewer things and replicate more times than it is to test more things and replicate fewer times.
February 1, 2013 – This series focuses on tools and approaches for attaining higher corn grain yields.
In the previous tip, the Hybrid Maize model was highlighted as a tool that predicts yield potential. Hybrid Maize relies on weather data. The more local the weather data, the more accurately potential yield can be estimated. Hybrid Maize comes with a tool called WeatherAid. It is found under “Utilities” on the main menu. This tool can format weather data from various sources into a format useable by Hybrid Maize. The following are some resources for weather information:
· National Aeronautics and Space Administration (NASA)
http://power.larc.nasa.gov/cgi-bin/cgiwrap/solar/agro.cgi?email=agroclim@larc.nasa.gov
· Midwestern Regional Climate Center
http://mrcc.isws.illinois.edu/
· High Plains Regional Climate Center
http://mrcc.isws.illinois.edu/
January 20, 2013 – This series focuses on tools and approaches for attaining higher corn grain yields.
In the previous tip, yield potential and yield goal were differentiated. Yield potential is determined with crop models that account for weather and crop management variables. A very useable and affordable model for estimating yield potential is Hybrid Maize. It may be purchased at: http://hybridmaize.unl.edu.
January 10, 2013 – This series focuses on tools and approaches for attaining higher corn grain yields.
Many scientists conducting high yield research work with yield potential rather than yield goals. Yield potential is, “…the maximum yield that could be reached by a crop in given environments” (Evans and Fischer. 1999. Crop Sci. 39:1544). It is estimated with crop models that take into account many environmental and management variables. Yield goals are future targets set by looking back at the average yields attained in the past few seasons. They are typically a few percentage points higher than past performance. They don’t reflect what is possible, only what is attainable given historical management.
January 1, 2013 – This series focuses on tools and approaches for attaining higher corn grain yields.
Winter is a good time to examine past yield performance. Comparing yield goals set at the beginning of the season to yields actually attained evaluates the historical accuracy of yield goals and helps improve how they are set in the future.
December 20, 2012 – Drought can change soil tests in several ways
- Reduced grain yield results in lower nutrient removal, damping reductions in soil test P and K;
- Corn planned for grain harvest but instead cut for forage increases nutrient removal, amplifying reductions in soil test P and K;
- Low moisture affects the reactions K has with soil minerals. These reactions impact the amount of K measured by soil tests and create swings in readings that cannot be explained solely by comparing K application rates with nutrient removals. In some cases, soil tests levels may be lower than expected and in some cases they may be higher.
December 10, 2012 – Impacts of drought on nutrient management for next year’s crop
Drought can cause changes in nutrient concentrations of various plant organs. The magnitude of these changes depends upon when the drought occurred and how long it lasted. Measuring nutrient concentrations in harvested crop portions can provide more accurate assessments than average rates.
December 1, 2012 – Impacts of drought on nutrient management for next year’s crop
Lower yields caused by the drought mean less P and K will be removed with grain harvest. If, on the other hand, corn that was intended for grain harvest was instead cut for silage, P and K removal will be greater than planned.
Some average rates of removal by corn and soybean are given in the following Table. Multiplying these rates by harvested yield estimates total removal.
Average P and K nutrient removal by corn and soybean.
November 20, 2012 – Impacts of drought on nutrient management for next year’s crop
On most soils in the Midwest, both P and K form chemical bonds with soil minerals that keep them from moving very far from the point of application. Unlike N, they are not subject to as many losses. Primary pathways for loss are erosion and runoff, and then, only the P and K near the soil surface. In mucks and sandy soils, K can be lost through leaching. So in most situations, P and K not taken up by the crop carry over for use in future years.
Comparing the amount of P and K applied before this season to the amount actually removed by crops this year provides an estimate of the P and K carrying over.
November 10, 2012 – Impacts of drought on nutrient management for next year’s crop
Considering the impact that drought has upon all the various factors that contribute to the soybean N credit, it is hypothesized that some, but perhaps not all, of the credit should be taken if corn is to be grown after this year’s soybean crop. A conservative approach would be to apply a basal amount of N that is reduced by the full credit and then monitor the corn crop and apply additional N if diagnostic tests (tissue tests, chlorophyll meter readings, or active crop reflectance sensors) indicate a deficiency.
November 1, 2012 – Impacts of drought on nutrient management for next year’s crop
If a soybean crop is planned for next year, it will simply scavenge the nitrate left. Higher nitrate levels do not adversely affect soybean yields. Under higher nitrate supplies, soybean derives less of its N from biological fixation, and total N uptake will likely be the same or somewhat higher.
October 20, 2012 – Impacts of drought on nutrient management for next year’s crop
Here are some options for addressing the uncertainty in N rate for next year, caused by residual soil nitrate and unpredictable weather conditions:
- Take soil nitrate tests to assess levels, paying attention to within-field variability.
- Move from fall to spring and in-season applications. This provides better synchrony between N supply and N uptake by the crop.
- Use a chlorophyll meter, such as a SPAD meter, or active crop reflectance sensors, to determine rates of N to side-dress.
October 10, 2012 – Impacts of drought on nutrient management for next year’s crop
Pulses of N can occur any time dry soils are rewetted. As soils dry, the microbial decomposition of organic matter that releases N (mineralization) slows, approaching zero under very dry conditions (less than 10-15% moisture). In addition, some soil microbes are killed. When dry soils are rewetted, a sudden pulse of inorganic N may occur, termed a “flush” or a “hot moment.” This pulse can last for days to weeks. A significant portion of this flush is thought to come from the decomposition of the microbes recently killed during the dry spell. Another contributor to the flush is the release of organic compounds from the reactive sites at clay mineral surfaces.
October 1, 2012 – Impacts of drought on nutrient management for next year’s crop
Where corn was grown, it is likely that nitrate (NO3-) levels in the soil are higher than normal. Higher levels arise from decreased downward movement of soil water and from reduced fertilizer N uptake by the drought-stressed plant.
September 20, 2012 –
Plan now to take a few grain samples when harvesting. Grain nutrient content can be used to help you calculate maintenance fertilizer applications. Consult with your adviser or trusted laboratory for guidance on taking and interpreting grain samples.
September 10, 2012 –
Thinking ahead to spring, many areas have seen recent increases in pre-season precipitation. If you normally applying N in the fall for corn the next year, consider switching to spring applications, either pre-plant or side-dress. Both of these applications are better for avoiding early spring losses of N.
September 1, 2012 –
A good way to increase the efficiency of a N application is to ensure that other needed nutrients are adequately supplied. When other nutrient limitations occur, crop responses to N are reduced. Investing in adequate soil fertility increases the returns on N inputs.
August 20, 2012 –
Soil K tests this year could be below expected levels. Drier weather often results in much lower K tests. Clay mineralogy contributes to this effect, as does the amount of precipitation coming after harvest and before sampling. As rain falls on crop residues, K is leached from the plant tissue and enters the soil surface. The more rain falls, the more K is leached, increasing K soil tests.
August 10, 2012 –
Late season K deficiency is harder to detect in corn, but here are some clues: delayed tassel emergence; dead tissue on leaf margins of older, lower leaves; smaller stalk diameters that lack strength; and ears lower to the ground (reduced internode length).
August 1, 2012 –
Disease and insect problems can be tied to nutritional disorders. For instance, soybean aphid populations tend to be higher where K deficiencies exist. The incidence of northern leaf blight can also be higher on K deficient corn plants. When collecting tissue samples to send to a pest/disease diagnostic laboratory, it would be wise to also collect tissue samples and have them analyzed for nutrient content.
July 20, 2012 –
This summer, plant nutrient status should be monitored. Erratic precipitation patterns have caused nutrient shortages in many areas. Check with your trusted laboratory or crop adviser for guidance on sampling plant tissues and interpreting results.
July 10, 2012 –
Nitrogen and K deficiencies occurred early in the corn-growing season this year. A primary cause is lack of water. Extended periods of dry weather, often lasting weeks, reduced plant uptake of these macronutrients. When dry periods hit, it may not be possible to stave off K and N shortages, even where adequate soil supplies exist. Where K deficiencies occurred, soil tests should be taken this fall to assess soil supplies.
July 1, 2012 –
Many corn plants this year have yellowing on the lower leaves. Two nutrients are likely the problem: N and K. Nitrogen deficiency exhibits yellowing starting from the leaf tip and working its way down the midrib in a “V” pattern (http://bit.ly/MozQkz). Potassium deficiency shows up as yellowing along leaf margins (http://bit.ly/MK9Or7).
June 20, 2012 –
When high yielding soybeans are grown in fields that have received banded applications of P and/or K, it may be important to ensure that soybean rows are placed directly over the bands. Unlike corn, which has a fibrous root system, soybeans have a taproot system that primarily grows downward early in the season. If soybean rows are placed directly over the fertilizer bands, roots have much greater chances of intercepting the nutrients. The advent of high precision GPS guidance systems combined with GIS has created the possibility of creating maps that show where fertilizer has been banded in a field. Empowered with such information, farmers can do a much better job of placing bands in one year a certain distance away from bands made the previous year or even the year before. Over time, networks of bands can be created to match 15 in. or 7.5 in. soybean rows. For instance, if a piece of equipment bands fertilizer on 30 in. centers, this application can be staggered over two years to create bands that are 15 in. apart, where every other band is one that was made the previous year.
June 10, 2012 –
For high yielding soybeans, there may be some improvements that can be made to the timing of P and K fertilization. Many producers calculate the amounts of P and K that are needed for both corn and soybean crops, then apply the combined amounts ahead of the corn crop. Because many soybean varieties are sensitive to chloride, which is a co-ion of potash fertilizers, applying the combined amount of K ahead of the corn crop makes sense. It allows the chloride an entire year to percolate through the soil and get farther down the soil profile, decreasing the concentration in the root zone of soybeans. This is particularly important when heavier applications of K are made. For P however, consider making separate applications of P for each crop, rather than combining them. Spring applications of MAP or DAP, both of which contain ammonium, allow both corn and soybeans to take advantage of an ammonium-phosphate interaction that improves the uptake of P. If P is applied only ahead of the corn, the residual P is still present for the next soybean crop; however, by the second season, the ammonium has converted to nitrate or other forms and is no longer available to provide the interactive benefit to soybeans.
June 1, 2012 –
Fertile ground is a part of a high yielding soybean environment. Spatial variability in soil fertility should be assessed and nutrient applications made to ensure that all parts of a field have adequate nutrients. Roots are the primary organ through which soybean plants take up nutrients. Foliar fertilization can be effective when small quantities of nutrients are needed during a very short period of time during the plant’s growth. But the roots are the workhorses that supply nutrients, so it is essential that they grow in fertile ground.
May 20, 2012 –
Soybeans get their N from three sources: 1) N2 fixation by Bradyrhizobium, 2) nitrate and ammonium in the soil, and 3) fertilizer N. On average, 50 to 60% of the N in soybeans comes from N2 fixation. Normally, the remainder comes from the N in the soil. The maximum amount of N2 that can be fixed is approximately 300 lb N/A. When fertilizer N is applied, it can reduce the amount of N2 fixation. This reduction is exponential. The first 45 lb N/A can reduce maximum N fixation to about 190 lb N/A. Applying 90 lb N/A can reduce it to 125 lb N/A. However, if N is applied below the zone of active nodules, which is below about 7 to 8 in., it doesn’t have nearly the inhibitory effect. For instance, application of 100 lb N/A in a deep band still allowed nodules to fix approximately 200 lb N/A. So deep banding of N may be a good placement for supplemental N in high yielding soybean environments.
May 10, 2012 –
High yielding soybean environments may have a greater chance of responding to fertilizer N, but at lower yields, there are still several situations where responses to N are more likely. These include poor establishment of the nodule system, extremely low soil N supplies at planting, plant water stress, soil pH problems, low soil temperature, or an absence of native Bradyrhizobium resulting from a cropping history with infrequent or no legumes.
May 1, 2012 –
Do nodules produce enough N to feed a high yielding soybean crop? A recent, comprehensive review of the scientific literature revealed that when soybeans yielded more than 67 bu/A, they responded positively to N additions 75% of the time. Therefore, in high yielding environments, fixed N and soil N supplies may not be great enough to meet the N demands of the plant, increasing the probability that soybeans may respond to N fertilization.
April 20, 2012 –
What is a reasonable target for high yield soybean production? There are many producers who belong to “100 bushel” clubs or something similar. The 100 bushel mark seems to be a common target across the Corn Belt, but is it reasonable? Evans and Fischer, in a paper published back in 2009, defined potential yield as the, “maximum yield that could be reached by a crop in given environments, as determined, for example, by simulation models with plausible physiological and agronomic assumptions.” The key here is “given environments.” Potential soybean yields in the southeast U.S. may be very different than in the northern Great Plains. At a much smaller scale, potential yield on a higher organic matter area at the bottom of a slope may be very different than potential yield on an eroded side slope. For those interested in trying soybean simulation models, links to two of them follow:
SoySim from University of Nebraska: http://soysim.unl.edu/
DSSAT from ICASA: http://www.dssat.net/
April 10, 2012 –
What will it take to grow high yielding soybeans? It takes a process of discovery. Farmers who grow significantly higher yielding crops usually dedicate a part of a field to experimentation. This is a “playground” where different combinations of things can be tried. Higher plant populations, closer row spacing, higher soil fertility, and variety selection are typical management practices that are investigated. Farmers often combine all these various practices together into a system that is tested and monitored over time. Such an approach helps identify the best “recipe” for higher yields; however it does not isolate which of the factors contribute the most to the yield increases. To get this kind of information, companion on-farm studies have to be conducted that investigate the effect of each factor in isolation, such as comparing higher fertility strips to business-as-usual fertility strips. Having both “recipe” studies and single factor studies empower farmers to know which factors are most important and how they combine to increase yields.
April 1, 2012 –
What will it take to grow high yielding soybeans? First, it will take a shift in focus. Soybeans are typically grown on soils managed for other crops in the rotation, such as corn and wheat. Very few producers focus on the unique nutritional needs of the soybeans themselves. Growing a high yielding crop, whatever it may be, requires attention to detail and a commitment to the process of discovering what combination of management practices produce the best results under local conditions. So soybeans will have to be seen as just as important as the other crops in rotation if significant yield gains are to be achieved.
March 20, 2012 –
In this series, we examine how plant nutrition helps get the most from the ever-increasing investment in a bag of seed.
A lot is being said about the improved drought tolerance of many new corn hybrids. Such genetic improvements depend on proper soil fertility to manifest themselves. It is well documented that both K and chloride play an important role in water regulation within the plant. A primary effect of these nutrients is in operating the stomata, which are small holes in the plant leaf. These holes are opened and closed by the plant to regulate how much water vapor it loses. When K and chloride are in short supply, the plant can’t regulate these openings properly, and the plant’s control over its water vapor losses is compromised. So to get the most from the premium paid for seed with improved drought tolerance, soil fertility needs to be well managed.
March 10, 2012 –
In this series, we examine how plant nutrition helps get the most from the ever-increasing investment in a bag of seed.
A lot is being said about the improved root systems of many new corn hybrids. Improvements may be coming from better root architecture and/or less root damage through improved resistance to root worms. While genetic improvements may be significant, the interaction of these root systems with their soil environment is equally significant. In this Quick Tip, we examine the influence of soil fertility on root to shoot ratios, explained below.
A root to shoot ratio is a way of describing how much of the plant’s dry matter (the plant material that’s not water) is in the root system compared to how much is in the above-ground portion. Higher root to shoot ratios mean that more of the plant’s dry matter is in the root system. Many feel that a big root system is very desirable – and it is, to a point. But like everything, there’s a healthy amount, and then there’s too much.
Soil fertility has a big influence on root to shoot ratios. When fertility levels are low, a corn plant will allocate more of it energy to root development. It has to. Roots have to explore a larger volume of soil to get the total, required supply of nutrients. Because the plant has only so much energy and resources to expend, the more it puts into the root system, the less is left for the above-ground portion, reducing shoot growth and yield. So lower fertility levels lead to greater root to shoot ratios and lower yield.
When fertility levels are in ample supply, roots do not have to explore as much soil to get their total supply. This means that the plant can allocate more of its energy to grain development. In this favorable soil environment, roots can develop to their intended extent without overdeveloping and taking resources away from the grain.
March 1, 2012 –
In this series, we examine how plant nutrition helps get the most from the ever-increasing investment in a bag of seed.
A lot is being said about the improved root systems of many new corn hybrids. Improvements may be coming from better root architecture and/or improved resistance to root worms. While genetic improvements may be significant, the interaction of these root systems with their soil environment is equally significant. In this Quick Tip, we examine the influence of soil fertility on root distribution in the soil.
It is well known that the distribution of roots in the soil is dependent on the distribution of fertility. Both N and P proliferate roots. When roots encounter soil volumes enriched in either one or both of these nutrients, more root laterals are developed, possibly arising from the plant allocating more photosynthates to the parts of the root system growing through these zones. While both N and P proliferate roots, only P can maintain a more nutrient rich zone over time. Placing P strategically over time can help proliferate roots at desired places in the soil.
February 20, 2012 –
In this series, we examine how plant nutrition helps get the most from the ever-increasing investment in a bag of seed.
Many farmers are observing improved corn yields with new genetics, and these yields are often coming with no changes in N management. Higher yielding corn does require more N, but does this additional N need to come from fertilizer? Three possibilities exist. In this Quick Tip, we examine the possibility that the soil may be supplying more N and the crop is producing more bushels with the additional N supplied.
The implications of this scenario are a combination of the points discussed in the previous two Quick Tips. Greater reliance on soil N supplies to meet the N demands of higher yielding corn endangers the soil’s ability to supply those needs in the future. More bushels per unit of N applied improve economic returns but create greater economic risk if N rates are inadequate.
February 10, 2012 –
In this series, we examine how plant nutrition helps get the most from the ever-increasing investment in a bag of seed.
Many farmers are observing improved corn yields with new genetics, and these yields are often coming with no changes in N management. Higher yielding corn does require more N, but does this additional nitrogen need to come from fertilizer? Three possibilities exist. In this Quick Tip, we examine the possibility that the crop may be producing more bushels with the same amount of N.
Producing more bushels without changing N rate means that the corn crop is using N more effectively. This translates to improved economic returns to N costs. In addition, it means there is a greater risk of yield loss if N rates are inadequate. So while reaping more bushels from the same amount of N improves net returns, it also increases the importance of ensuring that rates are adequate.
February 1, 2012 –
In this series, we examine how plant nutrition helps get the most from the ever-increasing investment in a bag of seed.
Many farmers are observing improved corn yields with new genetics, and these yields are often coming with no changes in N management. Higher yielding corn does require more nitrogen, but does this additional N need to come from fertilizer? Three possibilities exist. In this Quick Tip, we examine the possibility that the soil may be supplying the extra N needed.
Believe it or not, the soil acts like it has a memory. The quantities of nutrients it supplies today depend on the nutrient management practices of the past. Except for coarse, sandy soils, historically higher N rates allow the soil to provide more N to a corn crop. The scientific literature indicates that years producing good corn yields are also years conducive to greater release of N from the soil. So if past N rates have been adequate or above, it is likely that the soil is supplying at least part of the additional N needed by a higher yielding corn crop. While this is good news, we also need to be thinking about the future. If the additional N needs of higher yielding crops are being met by soil supplies, what is the sustainability of those reserves? This is an active area of research, but some studies have shown that soils with a history of lower N rates are not able to supply as much N to corn, creating a greater dependence on the N coming from fertilizer.
January 20, 2012 –
In this series, we examine how plant nutrition helps get the most from the ever-increasing investment in a bag of seed.
Many farmers are observing improved corn yields with new genetics, and these yields are often coming with no changes in N management. Higher yielding corn does require more N, but does this additional N need to come from fertilizer? Three possibilities exist. First, if the soil is a good supplier of N, it may be supplying the extra amount needed, requiring no change in management. Second, if the soil is a poor supplier of N, then the crop may be producing more bushels with the same amount of nitrogen. Third, the soil may be supplying more N and the crop is also producing more bushels with the additional N supplied. In the next Quick Tips, we briefly examine the implications of each possibility.
January 10, 2012 –
In this series, we examine how plant nutrition helps get the most from the ever-increasing investment in a bag of seed.
Many farmers are observing improved yields with new genetics. It‘s important to remember that higher yields result in greater removal of nutrients from the soil. The following table shows how much more K, expressed as K2O, is removed from the soil with yield increases of corn and soybean, rounded to the nearest pound:
Corn yield increase | Increased K removal |  | Soybean yield increase | Increased K removal |
(bushels/acre) | (lbs K2O/acre) | | (bushels/acre) | (lbs K2O/acre) |
10 | 3 | | 5 | 7 |
20 | 6 | | 10 | 14 |
30 | 9 | | 15 | 21 |
40 | 12 | | 20 | 28 |
January 1, 2012 –
In this series, we examine how plant nutrition helps get the most from the ever-increasing investment in a bag of seed.
Many farmers are observing improved yields with new genetics. It‘s important to remember that higher yields result in greater removal of nutrients from the soil. The following table shows how much more P, expressed as P2O5, is removed from the soil with yield increases of corn and soybean, rounded to the nearest pound:
Corn yield increase | Increased P removal | | Soybean yield increase | Increased P removal |
(bushels/acre) | (lbs P2O5/acre) | | (bushels/acre) | (lbs P2O5/acre) |
10 | 4 | | 5 | 4 |
20 | 8 | | 10 | 8 |
30 | 12 | | 15 | 12 |
40 | 16 | | 20 | 16 |
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