Category Archives: Fertility

Fertilizing Late Winter Forage

forage-3

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.

Leave a comment

Filed under Fertility, Forages

Good Time To Lime Ponds

limingpond-020

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.’

limingpond-016

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.

Leave a comment

Filed under Aquatic Environments, Fertility

Bermudagrass Leaf Rust

aliciabermuda-leafrust-010

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

Leave a comment

Filed under Disease, Fertility, Forages

Soil Health & Cover Crop Workshop – November 3rd

soilhealthcovercropworkshot

Leave a comment

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

Leave a comment

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.

Leave a comment

Filed under Fertility, Pecans

Pecan Leaf Sampling

Pecans 002

It is time for us to take leaf tissue samples in pecans.  UGA Extension Pecan Specialist Dr. Lenny Wells has this information:

The general recommended period for leaf sampling is July 7-August 7.

Why does it matter when you sample?

Concentrations of N, P, and Zn on a leaf dry weight basis start off relatively high early in the season, decline rapidly, reach a fairly steady state after mid-June, and then decline near leaf fall.  K tends to start high, then decreases and plateaus at about the same time as N, P, and Zn. Most of the P and Zn that accumulates in the leaves have done so by the time the leaves reach full size. Calcium (Ca) accumulates in the leaves as the season progresses, peaking in August-September. Magnesium (Mg) Manganese (Mn), and Boron (B) also tend to increase as the season progresses, but to a lesser extent than Ca.

PecanLeafSampling

Collect middle-pair leafleats

How do we sample?

  1. Collect 50- 100 middle-pair of leaflets from the middle leaf of this year’s growth (right). Use terminal shoots exposed to the sun. Avoid twigs from the interior of the tree. Collect leaflets from all sides of the tree. Avoid leaflets damaged by insects and diseases.
  2. Abnormal trees or trees not representative of the area should be sampled separately. A complete and accurate description of abnormalities should accompany these samples.
  3. Sample trees of the predominant variety in a given block. If Schley is the main variety, sample Schley; etc.
  4. Immediately upon collection, wipe leaves (entire surface, both top and bottom) with a damp cellulose sponge or cheese cloth to remove dust and spray residue.  Do not allow the leaves to come into contact with rubber or galvanized containers. Partially air dry and place in the large envelope of the mailing kit.
  5. If recent soil test data is not available, it would be advisable to collect a soil sample and have it sent to a soil testing laboratory.  By sampling the same trees each year, growers can more readily see the results of any changes to their nutritional programs.

**Some growers have taken leaf samples throughout the growing season to determine the fertility needs of the tree. This is really unnecessary. Leaf analysis does not necessarily reflect the actual use pattern of mineral nutrients, but instead indicates concentrations of those elements in the leaf at the time of sampling. The tree knows what it needs and when it needs it.

Concentrations of mineral nutrients in the leaves change as leaves emerge, expand, and finally senesce in the fall. For many elements, the least change in concentration occurs from early July-early August.

Leave a comment

Filed under Fertility, Pecans