Dr. Bob Lyons is an Extension Range Specialist based in Uvalde. He has done a lot of research into grazing habits and stocking rates. In a recent program Dr. Lyons showed some really neat information about a research project he conducted on a South Texas ranch. Basically what they did was to put Global Positioning Satellite collars on a herd of cattle at a 2000 acre ranch. These collars signaled back to the researchers exactly where all the cattle were at all times and even plotted if they were grazing (moving) or resting. All of this information could then be plotted out on aerial photos to determine where cattle were spending their time and consequently where they were grazing. This tracking information was then followed up with visual on the ground investigations of what was in an area that was grazed or not grazed.
For instance they found that there was an area of the ranch that the cattle just would not go into but from the aerial photos the ground looked like good grass. When they went to look they found that there was lots of grass, good grass, but there was also a lot of rock. In fact they found that with as little as 30% rock cover cattle will not go into a pasture. They will only use an area about 35% of the time if there is as little as 10% rock cover.
They also took soil survey information and laid it over the aerial photos to plot out grazing patterns by soil type. In this ranch they looked at two soil types, Rumple-Comfort and Comfort-Rock. Cattle consistently preferred Rumple-Comfort to Comfort Rock about 2.5 to 1. This means that cattle were in these areas 2.5 times more because the better soil grew better grass.
In another example a pasture section had no cattle grazing, in fact it showed up as a big hole in a pasture on their photos. When they went to investigate, this particular area was ringed in cedar. Now a cow could certainly get into this pasture area but she wasn’t going to simply because it was “walled” off with cedar.
In another example they found that no cattle had been in a pasture that looked like a “sea of grass.” Even from their pickups they couldn’t figure out why the cattle wouldn’t graze the grass until they got out and started walking. This particular pasture was almost solid threeawn grass species. This is a beautiful looking grass but unfortunately not at all palatable or nutritious and the cattle showed them it wasn’t by not eating it.
It doesn’t take long to understand that even though this ranch was 2000 acres, only a limited amount of it was available for grazing. In Williamson County there is lots of pasture and rangeland but of the over 300,000 acres that could be grazed how much really can be grazed. Use your livestock to show you any barriers to grazing and either fix them or subtract them from your grazing plans.
Thursday, August 27, 2009
Monday, August 24, 2009
Pond Weeds
This is certainly the time of year that pond weeds are most visible. I usually get a number of calls about all this “junk” on or in our tanks and ponds with the question, “what can I do about it?” Unfortunately there isn’t much we can do about it this time of year but maybe an explanation about the categories of pond weeds and some control measures might be helpful.
The first group of pond weeds are algae including plankton which makes the green color in water, filamentous algae or pond scum, and branched algae which includes chara or muskgrass that looks like underwater hay. This is probably the number one problem in tanks and causes the most aggravation. Pond scum usually begins growing near the bottom or edges of a pond and later floats to the surface where it then looks like a mass of wet, green wool. This type algae is best controlled by pond fertilization back in February. Since it starts at the bottom we can encourage the growth of plankton, which is a good algae, it will shade out the pond scum and keep it from growing. There is nothing worse than a clear pond because plankton is part of the food chain which eventually feeds fish. Chemically we control algae easily with copper or copper complex chemicals.
A second group of weeds are the floating plants. Duckweed is one that we have in abundance in our area and it is a small, floating plant, green in color and about ½ inch across with usually 3 leaves and below the leaves you can see a root. Diquat is a good, relatively inexpensive chemical control or you can rake this plant off the surface.
The third group is submersed plants. These plants are rooted to the bottom but generally don’t have plant parts above the water surface. The most common submersed weed is bushy pondweed which resembles coastal hay growing underwater. Another similar weed is coontail and it too can fill up a pond in short order. Diquat, endothall and floridone are all chemical controls or you may want to check into stocking your tank with triploid grass carp which do an excellent job of long term control of these problem weeds and do not cause a problem with other fish.
The last category includes our emersed weeds which includes all shoreline, marginal and shallow water plants with plant parts that extending above the water line. These include many species but most commonly we are dealing with cattails, willow, rushes, buttonbush, water primrose and frogbit. Most of the emersed weeds are easily controlled with glyphosate products which we commonly call Roundup although Roundup itself is not labeled for aquatic weed control. There are several name brand products that do contain glyphosate and are labeled for aquatics. Another excellent product for emersed weeds is 2,4-D.
Now the last question I usually get when talking about weed control in ponds is, “will it hurt my fish?” The chemicals themselves are harmless to fish but the dead vegetation they leave behind may not be. A lot of decaying vegetation will suck a lot of oxygen from the water and could leave your fish starving for a breath. It is best to control pond weeds a little at a time so that you don’t set yourself up for a problem one morning watching all your fish floating on the surface.
How Many Animals Can I Raise On My Place?
I can’t count the number of times I have been asked this question or better yet, “can you come to my place and tell me how many animals I can raise?” The question I have to ask is how much grass do you have? Of course no one knows or has even asked themselves this important question so let’s look at where we can go to begin the process.
On pages 114 and 115 of the Soil Survey of Williamson County (http://soildatamart.nrcs.usda.gov/Manuscripts/TX491/0/williamson.pdf) there is Table 6 Rangeland Productivity. This table lists every soil type for the county and the potential for annual production depending on the growing conditions. This would assume only range type plants and typical plant compositions are listed in the description of each soil series at the front of the book. A natural question arises, “what about coastal bermudagrass?” Since this assumes that the range plants are not fertilized we would also say that unfertilized coastal bermudagrass would respond similarly or slightly better. If the coastal is fertilized then we can increase the productivity of the plant, generally producing two times as much forage as without fertilizer.
Looking at Table 6 in the Soil Survey we can see for example that a Branyon (BrA or BrB) Blackland soil can produce 7,000 lbs of dry matter in a favorable year, 5,500 in a normal year and 4,000 in an unfavorable year. This would be the amount of forage produced if all the forage was cut and then dried and weighed. So it represents a total harvest for the year. You can find your soil type in the Soil Survey Maps!
Next, according to Range Scientists and Conservationists we can only expect to effectively use or consume 25% of the forage produced commonly known as “harvest efficiency.” 25% is consumed by the animal, 25% is lost to natural disappearance, and 50% is necessary for soil protection and future forage production.
So taking our previous example a Branyon Blackland soil in a normal year at 5,500 pounds of forage and only using 25% then we have 1,375 lbs of forage to consume per acre per year. A standard animal unit is considered to be a mature cow (1,000 lbs.) with or without calf consuming 26 pounds of forage per day (6 goats equals one mature cow). One acre produces 1,375 lbs divided by 26 lbs equals 52.88 days of grazing. 365 days divided by 52.88 equals 6.9 acres per animal unit per year in a normal year on a Branyon Blackland soil.
An Eckrant soil (EaD or EeB) produces only 1400 lbs of forage in a normal year. 25% yields 350 lbs of forage to consume divided by 26 lbs per day equals 13.46 days. 365 divided by 13.46 equals 27.11 acres per animal unit per year.
On pages 114 and 115 of the Soil Survey of Williamson County (http://soildatamart.nrcs.usda.gov/Manuscripts/TX491/0/williamson.pdf) there is Table 6 Rangeland Productivity. This table lists every soil type for the county and the potential for annual production depending on the growing conditions. This would assume only range type plants and typical plant compositions are listed in the description of each soil series at the front of the book. A natural question arises, “what about coastal bermudagrass?” Since this assumes that the range plants are not fertilized we would also say that unfertilized coastal bermudagrass would respond similarly or slightly better. If the coastal is fertilized then we can increase the productivity of the plant, generally producing two times as much forage as without fertilizer.
Looking at Table 6 in the Soil Survey we can see for example that a Branyon (BrA or BrB) Blackland soil can produce 7,000 lbs of dry matter in a favorable year, 5,500 in a normal year and 4,000 in an unfavorable year. This would be the amount of forage produced if all the forage was cut and then dried and weighed. So it represents a total harvest for the year. You can find your soil type in the Soil Survey Maps!
Next, according to Range Scientists and Conservationists we can only expect to effectively use or consume 25% of the forage produced commonly known as “harvest efficiency.” 25% is consumed by the animal, 25% is lost to natural disappearance, and 50% is necessary for soil protection and future forage production.
So taking our previous example a Branyon Blackland soil in a normal year at 5,500 pounds of forage and only using 25% then we have 1,375 lbs of forage to consume per acre per year. A standard animal unit is considered to be a mature cow (1,000 lbs.) with or without calf consuming 26 pounds of forage per day (6 goats equals one mature cow). One acre produces 1,375 lbs divided by 26 lbs equals 52.88 days of grazing. 365 days divided by 52.88 equals 6.9 acres per animal unit per year in a normal year on a Branyon Blackland soil.
An Eckrant soil (EaD or EeB) produces only 1400 lbs of forage in a normal year. 25% yields 350 lbs of forage to consume divided by 26 lbs per day equals 13.46 days. 365 divided by 13.46 equals 27.11 acres per animal unit per year.
Extension Weather Station
We have a new weather station at the Williamson County Extension Office in Georgetown. This new addition will serve as a valuable tool for us in Extension and also for farmers and homeowners in the area. An even more valuable tool is the website texaset.tamu.edu, which collects data from this weather station and other stations across the state. By selecting Williamson County on the map and then clicking on Georgetown, the site will give you daily evapotranspiration (inches of water lost from evaporation from the soil and from transpiration from plants), daily maximum and minimum temperatures, relative humidity, solar radiation, rainfall, and wind speeds at 4 am and 4 pm. The website also includes handy tools for calculating irrigation requirements for home lawns, turf and landscapes, and for crops. With each tool, you enter a few factors such as sunlight exposure, turfgrass type, type of crop, etc... and it will give you the water requirements and then you can enter information about your sprinkler system (watering rate in inches/hr) and it will calculate how long and how many times per week to run your sprinkler system.
The website also provides several useful links to other weather, hydrological, and irrigation websites. Again, the website is texaset.tamu.edu
The website also provides several useful links to other weather, hydrological, and irrigation websites. Again, the website is texaset.tamu.edu
Sunday, August 9, 2009
Nitrates in Forages, Should We Worry?
There has been a lot of worry on the part of livestock producers afraid that their forages may be high in nitrates. A few people have actually tested their hay but most just go on what their neighbor is saying and before you know it everybody has a nitrate problem when maybe only a few really do.
Warm-season annual grasses, such as forage sorghums, sorghum-sudan hybrids (haygrazer types), and the various millets can also accumulate nitrates to a level that is toxic to cattle during periods of dry weather. This list can also include weeds such as careless weed, lambsquarter, nightshades, and johnsongrass but really does not include bermudagrasses. Bermudagrasses are different because the nitrate accumulation would happen in the roots not the stems or leaves. I have never seen bermudagrasses with high nitrate problems. We can possibly also add rolled up corn and sorghum stalks that didn’t produce grain to the list this year.
Dr. Larry Redmon, Extension Forage Specialist sent me this article that I thought might help understand what is going on. Typical nitrate accumulation occurs with excessive N fertilization followed by a period of drought, although toxic levels of nitrates have been observed in warm-season annual grasses with as little as 50 lbs of N/ac under drought conditions. While aboveground plant growth is reduced, nitrate uptake continues to occur and concentrates in the forage tissue. Ruminants are affected because microbes in the rumen are able to convert nitrate to nitrite. Nitrite is then absorbed into the bloodstream where it converts hemoglobin, which carries oxygen throughout the bloodstream, into methemoglobin, which does not carry oxygen. Cattle death is due to asphyxiation.
The total level of nitrate in forage will determine whether or not the forage is safe to feed. Remember: Nitrate levels in hay do not diminish with time! Nitrate levels in silage may be reduced by 50% or more by the ensiling process but may still be excessive for safe feeding. Only a forage analysis for NITRATE (currently $5.00 at the Texas A&M University Soil Testing Lab) will determine whether or not the fresh forage, hay, or silage is safe to feed to livestock. Nitrate levels of 0.5% or 5000 ppm or greater may be dangerous to feed to animals and greater than 1.5% or 15,000 ppm are toxic to most classes of livestock. The official Texas A&M University advisory is to not feed forages that contain greater than 1% or 10,000 ppm nitrate. The more conservative number of 5,000 ppm, however, may be a much safer number to use in actual practice.
Producers using warm-season annual forages or johnsongrass should have their hay crops tested prior to harvesting. Look at the forages carefully. If the forage to be harvested for hay has been under drought stress, there is a good likelihood that it is high in nitrates. If a good precipitation event occurs and plant growth is reinitiated (good green color, no droopy leaves), then the forage may be safe to feed, but a forage analysis for nitrate would still be advisable. DO NOT HARVEST the forage and then test! To do so could wind up costing you time, effort, and money and result in a hay crop that you will not be able to feed. Likewise, cattle should not be pastured on warm-season annual grasses or johnsongrass if conditions are such that nitrate levels could be elevated to a toxic level. Again, only a forage analysis can determine if the forage is safe to graze.
Prussic Acid Can Be A Problem As Well
Certainly prussic acid can be a problem in our sorghum type plants but with the severity of the drought I haven’t really worried about prussic acid causing much of a problem. Most of the sorghums and johnsongrass were basically dead and without moisture they don’t produce prussic acid. After any rains produce new growth then this new growth will be the lushest of the plant and will contain the highest concentrations of prussic acid. I would caution producers to be careful of fields with a lot of johnsongrass or sudan in them after any rains. These will probably contain too much prussic acid to graze but after growing a couple of weeks the doses should come down and be fine.
Warm-season annual grasses, such as forage sorghums, sorghum-sudan hybrids (haygrazer types), and the various millets can also accumulate nitrates to a level that is toxic to cattle during periods of dry weather. This list can also include weeds such as careless weed, lambsquarter, nightshades, and johnsongrass but really does not include bermudagrasses. Bermudagrasses are different because the nitrate accumulation would happen in the roots not the stems or leaves. I have never seen bermudagrasses with high nitrate problems. We can possibly also add rolled up corn and sorghum stalks that didn’t produce grain to the list this year.
Dr. Larry Redmon, Extension Forage Specialist sent me this article that I thought might help understand what is going on. Typical nitrate accumulation occurs with excessive N fertilization followed by a period of drought, although toxic levels of nitrates have been observed in warm-season annual grasses with as little as 50 lbs of N/ac under drought conditions. While aboveground plant growth is reduced, nitrate uptake continues to occur and concentrates in the forage tissue. Ruminants are affected because microbes in the rumen are able to convert nitrate to nitrite. Nitrite is then absorbed into the bloodstream where it converts hemoglobin, which carries oxygen throughout the bloodstream, into methemoglobin, which does not carry oxygen. Cattle death is due to asphyxiation.
The total level of nitrate in forage will determine whether or not the forage is safe to feed. Remember: Nitrate levels in hay do not diminish with time! Nitrate levels in silage may be reduced by 50% or more by the ensiling process but may still be excessive for safe feeding. Only a forage analysis for NITRATE (currently $5.00 at the Texas A&M University Soil Testing Lab) will determine whether or not the fresh forage, hay, or silage is safe to feed to livestock. Nitrate levels of 0.5% or 5000 ppm or greater may be dangerous to feed to animals and greater than 1.5% or 15,000 ppm are toxic to most classes of livestock. The official Texas A&M University advisory is to not feed forages that contain greater than 1% or 10,000 ppm nitrate. The more conservative number of 5,000 ppm, however, may be a much safer number to use in actual practice.
Producers using warm-season annual forages or johnsongrass should have their hay crops tested prior to harvesting. Look at the forages carefully. If the forage to be harvested for hay has been under drought stress, there is a good likelihood that it is high in nitrates. If a good precipitation event occurs and plant growth is reinitiated (good green color, no droopy leaves), then the forage may be safe to feed, but a forage analysis for nitrate would still be advisable. DO NOT HARVEST the forage and then test! To do so could wind up costing you time, effort, and money and result in a hay crop that you will not be able to feed. Likewise, cattle should not be pastured on warm-season annual grasses or johnsongrass if conditions are such that nitrate levels could be elevated to a toxic level. Again, only a forage analysis can determine if the forage is safe to graze.
Prussic Acid Can Be A Problem As Well
Certainly prussic acid can be a problem in our sorghum type plants but with the severity of the drought I haven’t really worried about prussic acid causing much of a problem. Most of the sorghums and johnsongrass were basically dead and without moisture they don’t produce prussic acid. After any rains produce new growth then this new growth will be the lushest of the plant and will contain the highest concentrations of prussic acid. I would caution producers to be careful of fields with a lot of johnsongrass or sudan in them after any rains. These will probably contain too much prussic acid to graze but after growing a couple of weeks the doses should come down and be fine.
Pecan Weevil Time Again
It seems like such a very short time ago that we were dealing with pecan weevil problems and here we are again. Pecan producers are always concerned about pecan nut casebearer and rightfully so but for those producers that have pecan weevil problems in their orchard no other insect is as destructive.
The pecan weevil lives in the ground for at least two years before it emerges as an adult. The adult can fly but prefers to walk up the tree from the ground and begins finding nuts. The weevil has a long snout that it uses to puncture the pecan and either feed or lay an egg in the hole. This egg hatches out and the grub or larva feeds inside the nut before boring a hole in the shell and dropping to the ground. The hole you see in so many pecans is the result of the weevil leaving the pecan. The female weevil can feed in a pecan in the water stage but she cannot lay an egg in the pecan until the nut has the gel like substance inside. We are currently going from the water stage to the gel stage in many pecans.
Several things have to be together in order for the weevil to be a problem. First the soil has to be loose enough for the adult pecan weevil to leave the ground. We have had nothing but drought so soils are hard but weevils can emerge through ground cracks. Second be sure and check the pecans to make sure they are in the right stage of development. If the ground is loose or cracked and the pecans are right then lastly make sure you have the pecan weevil. Put out a white cloth under some limbs and then shake the limbs to knock out the weevils. Look for them on the sheet, if you find some then it is time to spray.
There are many sprays for pecan weevil but unfortunately there are no organic sprays. To minimize insecticide use small growers may want to try a trunk spray. Carbaryl commonly known as Sevin is an excellent material since it has a very low toxicity and is easily found. Since most yard trees are very big it is really easier for a homeowner to apply Sevin to the trunk instead of the entire tree. Soak the trunk from the ground to breast high and the weevils will walk up the tree and of course contact the poison. The largest portion of weevils do walk up the trunk so this makes for an easy homeowner or small orchard treatment that is generally quite effective.
Pecan Weevil Facts You May Not Know
The pecan weevil is one of the most destructive pests of pecans. Most people have more problems with it simply because this insect infests nuts we have already taken through the season. There is nothing worse than spending money on a pecan and then seeing an insect eat it and we are right at the time for pecan weevil to be a problem.
Here are just a few facts about pecan weevil you may not know. The death rate in a 2 year cycle for weevil is 66.9-96 percent and for 3 years is 99.6 percent. We lose a lot of pecan weevils before they ever get out of the ground! Males feed on an average of 0.29 nuts per day while females feed on 0.23 nuts per day. We always worry about the number of pecans damaged from feeding but that is very small compared to egg lay in the pecan. Males live on average 21 days while females live 23.8 days. It takes 5 days from ground emergence for a female to start laying eggs. Females lay eggs in an average of 22.7 nuts per female. It doesn’t take too many weevils to mean a lot of damage. For many commercial growers even one weevil is too many. These early emerging weevils can be costly but the late weevils can end up in a sack of saleable pecans which is a real problem.
The pecan weevil lives in the ground for at least two years before it emerges as an adult. The adult can fly but prefers to walk up the tree from the ground and begins finding nuts. The weevil has a long snout that it uses to puncture the pecan and either feed or lay an egg in the hole. This egg hatches out and the grub or larva feeds inside the nut before boring a hole in the shell and dropping to the ground. The hole you see in so many pecans is the result of the weevil leaving the pecan. The female weevil can feed in a pecan in the water stage but she cannot lay an egg in the pecan until the nut has the gel like substance inside. We are currently going from the water stage to the gel stage in many pecans.
Several things have to be together in order for the weevil to be a problem. First the soil has to be loose enough for the adult pecan weevil to leave the ground. We have had nothing but drought so soils are hard but weevils can emerge through ground cracks. Second be sure and check the pecans to make sure they are in the right stage of development. If the ground is loose or cracked and the pecans are right then lastly make sure you have the pecan weevil. Put out a white cloth under some limbs and then shake the limbs to knock out the weevils. Look for them on the sheet, if you find some then it is time to spray.
There are many sprays for pecan weevil but unfortunately there are no organic sprays. To minimize insecticide use small growers may want to try a trunk spray. Carbaryl commonly known as Sevin is an excellent material since it has a very low toxicity and is easily found. Since most yard trees are very big it is really easier for a homeowner to apply Sevin to the trunk instead of the entire tree. Soak the trunk from the ground to breast high and the weevils will walk up the tree and of course contact the poison. The largest portion of weevils do walk up the trunk so this makes for an easy homeowner or small orchard treatment that is generally quite effective.
Pecan Weevil Facts You May Not Know
The pecan weevil is one of the most destructive pests of pecans. Most people have more problems with it simply because this insect infests nuts we have already taken through the season. There is nothing worse than spending money on a pecan and then seeing an insect eat it and we are right at the time for pecan weevil to be a problem.
Here are just a few facts about pecan weevil you may not know. The death rate in a 2 year cycle for weevil is 66.9-96 percent and for 3 years is 99.6 percent. We lose a lot of pecan weevils before they ever get out of the ground! Males feed on an average of 0.29 nuts per day while females feed on 0.23 nuts per day. We always worry about the number of pecans damaged from feeding but that is very small compared to egg lay in the pecan. Males live on average 21 days while females live 23.8 days. It takes 5 days from ground emergence for a female to start laying eggs. Females lay eggs in an average of 22.7 nuts per female. It doesn’t take too many weevils to mean a lot of damage. For many commercial growers even one weevil is too many. These early emerging weevils can be costly but the late weevils can end up in a sack of saleable pecans which is a real problem.
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