Category Archives: Fertility

Sidedressing Corn

We are very thankful for timely rains without significant storms. We’ve had atleast 1.5″ of rain in the last 7 days. This has helped get our pre-emergent herbicides activiated. This is also good for dryland corn, as it approaches the critical V6 growth stage where much of its yield is determined.

Ground Equipment

It’s not time to sidedress. We want 1.2 lb of total N per bushel goal. UGA Extension Fertility Specialist Dr. Glen Harris recommends sidedressing at 12″ to 16″ height. If we’re using ground equipment, we’re putting out 50 to 75 lbs of N per at at / before planting on irrigated land and 20 to 50 lbs of N per acre in dryland. We put out the rest of the N at sidedressing.

Fertigation

You put out 40 – 60 lbs of N at or before planting and start ground or injected applications of 30 – 60 lbs of N per acre when corn is 8″ to 12″ tall. Keep this going every other week until the total required N is finished. You’ll need 3 to 5 applications during the growing season.

Sulfur

Corn requires about 20 to 30 lbs of Sulfur and we sometimes see sulfur deficiency. It looks similar to N deficiency except we see an overall yellowing of the corn plants. (N deficiency shows up in the lower part of the plant since it is plant movile.) To be sure of which deficiency, we need to take a plant tissue analysis. I talked about the proper way to do this for corn in this blog post.

Only on sandy soils do we split our S applications. Whatever we don’t put out at planting needs to be put out now. Research has shown that we want to correct our S deficiencies between 21 and 30 days old to not hurt yield.

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Fertilizing Late Winter Forage

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We were months late getting our winter forage planted this year. We didn’t have many options because of this, so most winter forage is ryegrass. Most of it is looking good now and very green. We haven’t had too much rain to leach nutrients, and weather has been similar to a normal October/November. We typically put 50 lbs of N at planting, in winter, and again in spring. We will still be able to get in another few fertilizers if need, but probably one less than normal. At this time, we need to check small grains for deficiency and put on another 50 lbs when we see the lower leaves yellowing.

N deficiency in triticale

N deficiency in small grain

Last season, winter rains leached our nitrogen from the soil, and timeliness with winter fertilization was critical. UGA Forage Agronomist Dr. Dennis Hancock sent out information on ryegrass last year to address issues with heavy rains:

Ryegrass

Standard soil test recommendations are that one should put out 50 lbs of N/acre on ryegrass and small grains in late winter (late January – February) and another 50 lbs of N/acre on ryegrass in early spring (mid-March – mid-April). Applications of N at these rates are likely to result in more than 15-20 lbs of DM per lb of added N for the late winter application and more than 20-25 lbs of DM per lb of added N.  As a general rule of thumb, N response rates greater than 15-20 lbs of DM per lb of added N will result in an economical response.

The response to N (lbs of DM gained per lb of added N) has to be considered in context. To illustrate this, let us consider three scenarios:

Scenario 1) Ryegrass or small grains that have been slow to grow, either because of bad weather or N deficiency (and, sometimes, a late planting). These winter annual forage crops will often respond very aggressively to a winter application (20-30 lbs of DM per lb of added N assuming N rates are 40 – 60+ lbs of N/acre).  It is analogous to compensatory gains in growing livestock. It is the same basic principle: an organism that has had growth limitations will often grow at extraordinary rates whenever those factors are no longer limiting.

Scenario 2) Ryegrass or small grain plantings that have been growing strong. Winter annual forage crops in this scenario are unlikely to respond as aggressively to N at this time. For example, they may barely provide 15 lbs of DM per lb of added N during the few weeks following N application. However, this N is still crucial, as it keeps the plant growing at least at a healthy rate. Therefore, it is important to fertilize them at the same or nearly the same rates because they will need the fertility during the remainder of the season.

Scenario 3) Winter annual forages that have been moderate to severely damaged by disease (Helminthsporium leaf spot, grey leaf spot/blast, leaf rust, or barley yellow dwarf virus, etc.). These forage crops are unlikely to respond to N application. For example, tillers that are exhibiting physical symptoms of barley yellow dwarf (BYD) infection will die quickly, especially following a hard freeze. Therefore, if more than 30% of the tillers in a stand of oats have been damaged by barley yellow dwarf, those plants are unlikely to respond well to N. Each producer will have to determine if they are willing to take the risk, but if it were my oats, I doubt I would put any more N into those areas/fields.

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Good Time To Lime Ponds

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We talk about weed issues in ponds, but another aspect of pond management is fertilization and liming. Haphazard fertilization programs are not recommended in ponds. However, liming every few years has cultural benefits to a pond and keeps the water alkalinity above 50 parts per million (ppm) which is better for certain herbicides.

When the soils become more acid, important pond nutrients like phosphorus (P) is not available to algal production. Phytoplankton are important for fish ponds for the production of oxygen. They also convert nutrients like ammonia, which can be toxic to fish, into a non-toxic form.

We spend a lot of time looking at pond weeds during the summer. When we have filamentous algae, we use compounds with copper. Copper that is toxic to plants and parasites in pond water is also toxic to catfish when the water is very soft. Copper sulfate is an example of these herbicides that is more likely to cause fish toxicity. Alkalinity needs to remain above 50ppm.

Testing Water

If there is no water in the pond, you can do a routine pH test on the soil. But it is not recommended to do a pH test of the water, because pH in water changes during the day. It is better to calculate the hardness of the water. UGA Extension Aquatic Specialist Dr. Gary Burtle has worked with the UGA Water lab in developing a pond water test. In my experience, if the pond has not been limed in a few years, it’s going to need lime. I’ve never seen a test come back that said no lime needed.

Sources of Lime

The real issue is solubility and particle size. Dr. Burtle says most of the lime should pass through a screen size of 200 meshes per inch. Lime larger than 60 mesh is too large; it dissolves too slow. Hydrated lime is a good lime for ponds, because it is more soluble in water than calcium carbonate.

Dr. Burtle recommends apply only 50 lbs of hydrated lime per acre in a single application in order to avoid creating ‘hot spots.’

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Lime that passes through a 200 mesh, such as hydrated lime, is recommended for ponds.

Method of Application

If no water is in the pond, agriculture lime can be applied on dry pond bottom. Soil test of pH can determine the need.

With water, the worst thing we can do is dump lime in the pond from the edge. It is also not recommended to lime the perimeter of the pond. You need a boat to do it properly. Specialized equipment is also needed to calibrate correctly. Here In the top photo is Alan Dennard and Ken McKinis liming a pond a few weeks ago. They would make several passes over to not create hot spots.

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Bermudagrass Leaf Rust

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It’s not unusual for us to be dry in October. But it is unusual to go into October already dry. Many folks have not seen one measurable rain in the month of October. As we walked through this Alicia hay field, our boots were covered in rust spores. Clouds of rust were seen with each step. Leaf rust this time of year is pretty typical in Alicia. We may not see it exactly this bad with Coastal.

Identification

Will rust, you will see red to orange lesions on the leaf and stem. Look for a raised area or blister which is the rust postules like we see in wheat and corn. Rubbing your finger over the leaf will leave a rusty color.

Leaf Rust

Leaf Rust

Leaf Rust

Postules of rust are raised

Management

We cannot use fungicides on our hay fields, so management is strictly avoidance. Coastal, Tift 44, and Tift 85 have some level of resistance while Alicia is extremely susceptible. But even less susceptible varieties are infected with leaf spot when POTASSIUM is low. Most reported leaf spot cases are directly related to low soil potash. Nutrients are removed from bermuda hay fields in about a 4-1-3 ratio of N, P2O5, and K2O with harvest. We need 75 percent as much potash as nitrogen  applied each season. Split applications of K are better in sandy soils. In these cases, nearing the end of the season, we need to go out with another shot of straight potassium.

Visit Leafspot Diagnosis and Management in Bermudagrass Forages for more information.

Leaf rust on boots

Leaf rust on boots

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Filed under Disease, Fertility, Forages

Soil Health & Cover Crop Workshop – November 3rd

soilhealthcovercropworkshot

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October 28, 2016 · 6:56 PM

Herbicide, Fungicide, Foliar Fertilizer Combinations In Peanut

We have been fortunate in our county with adequate rainfall – in most areas anyway. Peanut crop is looking good, we have set pods and kernels are developing in our oldest peanuts. With many questions concerning mixing chemicals, and foliar fertilizers, here is an update on current peanut condition from UGA Extension Agronomist Dr. Scott Monfort:

We tend to think July is the half way mark for the season but the truth is we have a long season ahead of us due to the late plantings throughout the state. There are many acres that are lapped and are setting pods while others are barely 8 to 10 inches wide and are struggling to grow. The good news is a majority of the crop looks good with a large part of the area receiving some rains over the last couple of weeks. However, there are many dry areas that need rain. In some of these areas, a few peanuts have stopped growing and blooming as well as showing signs of elevated leaf burn (with some leaf scorch) as a result of applications of different combinations of adjuvants, herbicides, fungicides, and foliar fertilizers being made in extremely hot and dry conditions (mid to upper 90’s and bright sunny days). A few of these fields have lost more than a third of their leaves. Growers should use caution regarding potential burn as a result of these applications but it’s not something you can eliminate due to weeds and diseases need to be addressed.

Foliar Fertilizer?

I have noticed foliar fertilizers being recommended in these situations to turn the dry land field around. The problem is, the peanuts have shut down due to lack of moisture and are not going to recover until they receive rain. The use of the foliar fertilizer is only costing the growers money and adding to the excessive foliar burn. The best thing to do is to not add these products to their fungicide or herbicide applications under these conditions. Growers can also limit burn by not spraying during the middle of the day (again this might not be an option as growers have a lot of acres to cover).

Leaf Scorch - Dr. Scott Monfort

Leaf Scorch – Dr. Scott Monfort

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Filed under Fertility, Peanuts

Soil Testing Pecan Herbicide Strips

Pecan-Background (7)

This is pecan leaf sample time – July 7 through August 7. In addition to leaf samples, UGA Extension Horticulturalist Dr. Lenny Wells has information on soil testing, particularly in row middles.

Many have found that pH in the herbicide strip is lower than that found in the middles. When we were doing the work on fertilizer placement and comparing broadcast band applications of dry N fertilizers with broadcasting over the whole orchard area, herbicide sprayer application of N, and injecting N through the irrigation system, we observed that soil pH is always lower in the herbicide strip regardless of the fertilization method you use (Pecan Response to Nitrogen Fertilizer Placement). We do have the potential to drop the pH faster in some situations where you concentrate fertilizer N in the strip, but its always lower in the strip. This is because the vegetation growing in the middles keeps the organic matter levels up, which helps to buffer soil pH, allowing it to remain a little more stable than areas free of vegetation.

Managing soil chemistry in the herbicide strip is vitally important because that is where the tree’s feeder roots are located around irrigation emitters. After their transformation to nitrate-N, both ammonium and urea fertilizers have an acidifying effect on the soil to which they area applied. In order to manage this, growers should take their soil samples within the herbicide strip and lime based on this reading. Because the vegetation in the middles helps to buffer the pH, you probably won’t need as much lime in those locations. It would be wise to check pH in the middles every few years and make an additional lime application to the middles when pH drops below 6.0.

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