Using the Most of NPK: Manure Applications on Cropland
by: Dr. Mario Villarino, County Ag Extension Agent
This week several concerns related to manure usage on grass pastures came to the Hopkins County Extension Office. Some producers wanted to know the difference between using chicken manure or liquid dairy manure. I took time to talk to Dr. Saqib Mukhtar, Associate Professor & Extension Specialist, Department of Biological & Agricultural Engineering, Texas A&M University, College Station, as he commented- Both manures (chicken and liquid dairy) have NPK and other nutrients plus organic matter. Chicken manure is usually higher in N content than the dairy manure. I would recommend an analysis of the nutrient content for both types of manure and then decide which one will fit the producer’s nutrient plan better from the P standpoint. Also, producers should consider if applying liquid manure on their pasture is also meeting his goal to provide some water to meet the water needs of his pasture also. In any case, producers should have a good idea what amounts of NPK will be put out to the pasture using either manure. One more factor may be odor emissions. Liquid poultry manure may carry more odors than liquid dairy manure, generally due to its higher N content than dairy manure. So, if odors are a concern for producers due to vicinity from neighbors or roads they may decide to go with liquid dairy manure. Like many things in life, for you to be able to know how much to use of a products, you MUST find out how much of the different components are into the mix. This is where testing plays a role into identifying the nutrient value of the manure. So, before you invest money, make sure you test the manure for NPK (testing can be done at Texas A&M University) to determine the quantity of NPK on the mix and then evaluate the cost per unit you are buying. The other part to consider is how much nutrients do you need on your land, and that can be done by soil testing. It usually takes between 1-2 weeks to get the results back with a cost of $10 per sample, depending of the laboratory that you use but is money very well invested.
Moving into another subject, mealybugs were spotted in the North east side of Hopkins County. Plant damage is caused by loss of sap extracted by high numbers of mealybugs, resulting in wilted, distorted and yellowed (chlorotic) leaves, premature leaf drop, stunted growth, and occasionally death of infested plants or plant parts. Ground mealybugs are white and 1/8 to 3/16 inch long. Ground mealybugs are covered with fine wax that can give the soil a bluish appearance. Foliage feeding mealybugs are covered in wooly white fuzz with distinct filaments; they range in size up to á inch in length. The ground mealybug feeds on the roots of anemone, chrysanthemum, gladiolus, iris, and other plant species. Aerial mealybugs aggregate and are common on the undersides of leaves and where a leaf attaches to a stem. Damage is caused by mealybugs feeding, and injecting toxins or plant pathogens into host plants. Mealybugs also secrete honeydew. Mealybug feeding can cause premature leaf drop, dieback, and plant death. Generally, female mealybugs go through 4 developmental instars and may oviposit up to 600 eggs, usually in a cottony-like ovisac beneath her body. The eggs hatch in 6 to 14 days into "crawlers". They can survive only 1 day without feeding, and once they insert their stylets to feed they generally remain anchored permanently. The crawler stage is the most easily controlled stage. Many pesticides are available to consumers wanting to control scale (mealybugs are consiederd scale insects). These can be divided into three general groups based on how they control scales: Some poison the insects; others suffocate them or cause them to dry out and die; and still others, called insect growth regulators or “IGRs,” disrupt molting. The most common group of poisons is the nerve poisons. These insecticides disrupt an insect’s nervous system. They are absorbed through the insect’s exoskeleton “skin” and are considered“contact insecticides.” Common contact insecticides
include carbaryl, diazinon, chlorpyrofos, pyrethrins, and permethrin. Other poisons have “systemic” activity, meaning that when they are applied to the plant’s leaves or
roots, the plant absorbs the insecticide into its tissue, and the scale insect is poisoned when it feeds from the plant. Examples of systemic insecticides are imidacloprid,dimethoate and disulfoton. Some products, such as acephate and dimethoate, are both contact and systemic insecticides. Scale insects are suffocated by oils and dried out by insecticidal soaps. Consumers may buy two kinds of oils for treating scale insects: dormant oils; and summer horticultural
or parafinnic oils. Both types affect immature and adult scale insects. Dormant oils may be applied only to deciduous plants (trees and shrubs that lose their leaves in the fall) when the plants are dormant. Be careful with evergreen plants:
These oils may injure
or discolor some species. Summer oils are lighter than dormant oils and may be applied during the summer on deciduous plants and throughout the year on many evergreen trees and
shrubs. Some horticultural oils may also be mixed with other insecticides to control scale insects more effectively. Insecticidal soaps disrupt the waxy cuticle or “skin” of the insect, which eventually causes the insect to dry out (desiccate) and die. Insect growth regulators interfere with an immature scale insect’s ability to molt (shed its outer skin to allow for growth); in some cases, IGRs suppress egg development. Although these insecticides often act more slowly than contact insecticides, they can effectively control many species of scales. For more information on these or any other agricultural topics please call the Hopkins County Extension Office at 903-885-3443 or e-mail me at mavillarino@ag.tamu.edu.
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