In this issue: Drought monitor, Harvest Celebration, Precision Soil Sampling, Prussic acid, Feeding Cottonseed to bulls.
It has been another exciting few weeks in Colquitt County agriculture. The cotton harvest is in the short rows, and folks are looking forward to the end of the year. Below is the latest drought monitor that was released on November 22, 2022.
Information regarding the drought monitor is also available at the county level. Colquitt County is still in moderate drought, or D1, according to this data, and it hasn’t altered from the previous week. These figures from the drought monitor are listed below.
Precision Soil Sampling: Grid Size Efficacy Vs. Cost Considerations
Variable-rate application of lime and fertilizer is a common practice to address soil nutrient variability within the agricultural fields. When it comes to precision soil sampling to determine site-specific nutrient requirements, grid sampling still remains one of the most widely used methods due to its ease of implementation and not requiring any additional data layers. In a grid sampling strategy, the field is divided into grids of a pre-defined size and soil samples are collected from each grid to determine the spatial soil pH and nutrient variability within the field. The size of the sampling grids can range from 1.0 to 5.0 acres (or larger) but a smaller grid size is generally recommended to accurately capture the difference in nutrient levels. However, smaller grid size also means more samples and greater sampling costs. While soil sampling on larger grid sizes (≥5 ac) may help cut down on sampling costs, it also presents an argument about the effectiveness of larger grids in accurately depicting the spatial variability within the field. Therefore, one of the most common questions being asked every year is related to the size of the sampling grid. This is an important question as growers want to make better data-driven nutrient management decisions while also being cost-effective with their soil sampling strategy.
To answer this question, we conducted soil sampling using grid sizes of 1.0, 2.5, 5.0, 7.5 and 10.0 ac in nine different fields ranging from 20 to 93 acres in South Georgia in 2022. The actual spatial nutrient variability within each field was also determined using high intensity sampling (2-3 samples/ac). Spatial nutrient maps and the corresponding variable-rate prescription maps were created using each grid size. From that, the application accuracy, total fertilizer applied and the application cost were calculated for each strategy. Figure 1 below shows the spatial K maps for soil sampling using 2.5 (left), 5.0 (center) and 10.0 (right) ac grid size for one of the fields. The difference among the maps depicting soil K variability is pretty obvious and was expected. A similar trend was noticed for soil pH and P in all fields. READ MORE
Watch Out for Prussic Acid !!
This is the time of year cattle producers need to be careful of Prussic acid. Prussic acid poisoning may occur when livestock consume certain forages and wild plants. Prussic acid is also called hydrocyanic acid or HCN. HCN can build up to toxic levels in leaves of plants such as Johnsongrass, sorgum, sudangrass, sorghum-sudan hybrids and wild cherries.
There have been many questions about grazing sorghum. Grazing susceptible forages may be very dangerous. This is because cattle prefer grazing young leaves and shoots which could be high in HCN or Prussic acid. Also this time of year producers have to be careful. The reason for this is that any condition that alters normal plant growth including drought of frost will usually cause higher levels of HCN.
Here are some other things to keep in mind.
1. Higher nitrogen rates will increase HCN potential.
2. There is more HCN in the leaves than in the stems. The topmost younger leaves contain more HCN than do the lower leaves.
3. Younger plants contain more concentration of HCN than older plants.
Here are some guidelines for avoiding Prussic acid poisoning.
1. Do not turn in hungry cattle. Feed some hay first then turn in cattle in late afternoon.
2. Follow fertilizer recommendations to assure adequate soil phosphorus. Avoid high levels of nitrogen.
3. Forage sorghums may not be safe for grazing until headed out.
4. Allow plants to reach at least 18 to 24 inches in height before grazing. HCN is present in large amounts only in the rapidly growing portion of the plant.
5. Use EXTREME CATION when allowing animals to graze after frost. A light frost may only kill the tops of plants. New shoots may develop which are high in HCN and these new shoots are preferred by livestock.
6. Plants that is safe to graze before the frost (above 18 inches or headed sorghum) can be safely grazed 7 to 10 days following a killing frost.
7. Plants that were too short for safe grazing before a killing frost should not be grazed for at least two weeks.
8. If you are not sure call someone who knows.
How much nitrogen to apply to my winter grazing? If you have cool season annual forages, apply 40 to 50 lbs. of nitrogen (N) per acre at planting or soon after the plants emerge to increase growth, tillering (thickening of the stand), and provide earlier grazing. A second application of 40 to 50 lbs. of N per acre should be applied in mid-winter to increase winter and spring forage production. If you have ryegrass in your forage program then a third application of 40 to 50 lbs. of N per acre may be needed in early spring.
When can I start to graze my winter forages? Grazing is one of the best uses for cool season annual grasses; however, the species differ somewhat in their tolerance of grazing. Ryegrass and rye are generally very tolerant of repeated grazing, while triticale generally does not regrow quickly. Barley, wheat, and oats have poor grazing tolerance.
Grazing can begin as soon as the plants are well-established and have accumulated four inches (or more) of growth. Begin with a light stocking rate and gradually increase as the growing conditions improve and forage growth rate increases. Consider the forage quality, nutritional needs of the animals, amount of forage present, availability, and the cost of other feed items when deciding how many animals to graze. Restricting the animal’s time on the paddock, rotating animals between paddocks, or using strip grazing techniques will improve utilization and reduce damage to the stand. Grazing when the soil is too wet (when animals’ hooves can bog in the soil) can severely damage winter annuals and will decrease potential production.
I receive the question about feeding cotton seed several times a year from producers. Hopefully this article from Dr. Lawton Stewart and Dylan Davis can shed some light on this.
Answering the age-old question: Is cottonseed going to make my bulls infertile?
Nov 15, 2022
Dylan Davis and Lawton Stewart
As winter slowly approaches and producers are planning their winter supplementation, the question comes in each year; can I feed whole cottonseed to my bulls or will it make them infertile? This article will go over the impacts of cottonseed on bull fertility and describe how to safely take advantage of cottonseed without negatively impacting fertility. READ MORE
We have also been very busy over the last couple weeks with cotton research plots. Information from this on farm research will be out very soon. The on-farm research conducted in Colquitt County could not be possible without the help of local cotton gins, producers, and industry.
If you have questions please contact me at the Colquitt County Extension office and have a safe Thanksgiving Weekend.
Jeremy M. Kichler
Colquitt County Extension Coordinator