Burndown time has come and gone for many in Tennessee. However, for those utilizing cover crops in their production system, many acres have yet to be terminated. Here are a few thoughts and strategies for effectively terminating cover crops as we prepare for Plant 25.
This spring some fields seem to be infested more heavily with wild garlic, grape hyacinth and in a few cases, star-of-Bethlehem. These three weeds, in the Lily family, are often mistaken for each other as they all derive from bulbs and are low-growing perennials. Continue reading
A big question this spring is how does one control Palmer amaranth in Xtend soybean with no dicamba option? The fundamentals of leaning heavily on herbicides that provide good residual control of pigweed is the answer. Starting in about 2019, the most consistent strategy to control Palmer amaranth has been overlaying residuals. That was because POST options started becoming less reliable due to the evolution of dicamba/2,4-D resistance stacked onto pigweed already resistant to glyphosate, PPO and ALS- inhibiting herbicides. Continue reading
Most of the soil nitrogen (N) is present in organic form, especially in the top 6 inches (75 – 95%), which is not readily available for plant uptake. Only about 0.1 – 0.3% is in inorganic or bioavailable forms such as nitrate and ammonium that plants can utilize. So, organic soil N is converted to inorganic forms for plants use, a process referred to as mineralization. The fraction of organic soil N that can be converted to inorganic form is referred to as potentially mineralizable N. Several factors including soil, previous crop, weather, and nitrogen management determine the extent of N mineralized. Nitrogen rate trials (>30) conducted over the past five years in West and Central TN suggested that mineralized soil N can contribute more than 20% of the total crop N requirements. Current N fertilizer recommendation for corn in Tennessee is based on realistic yield goals, which does not account for potentially mineralizable N that is available for the plant. Continue reading
Ryegrass and poa control can become more problematic when horseweed must also be controlled. Simply dropping dicamba in the tank with glyphosate and/or clethodim to control the horseweed will compromise the grass control of those two herbicides. So, is there a herbicide that can be added to glyphosate or glyphosate + clethodim that will provide horseweed control while not sacrificing ryegrass control? There is really only one option that is in good supply that would fit the bill. Continue reading
Ryegrass has become a major issue in many Tennessee fields. For managing GR ryegrass, it is best to do it as early as practical and utilize a clethodim + glyphosate tankmix. This tankmix needs to be applied at least 30 days ahead of corn planting to use a clethodim rate that has any chance of controlling well established ryegrass. Continue reading
Nitrogen management in most row crops can be a significant proportion of the overall production cost and can impact the bottom line. Keeping tabs on factors that can reduce the efficiency of N applications and deploying appropriate management strategies is one of the several ways to ensure a profitable production in this season. Nitrogen loss is one of the several factors that can reduce N application efficiency. The most common loss from broadcast or dribbled, unincorporated urea-containing fertilizers is ammonia volatilization losses, especially in no-till production systems. Ammonia volatilization occurs when ammonium ion from the breakdown of urea or fertilizer is subsequently converted to ammonia gas, which escapes to the atmosphere. The striking thing about ammonia volatilization losses is that nearly 90% of the total losses occurs within 3-5 days after fertilizer application. The potential and extent of ammonia loss is dictated by three key factors including soil properties, fertilizer management practices, and environmental conditions. This article focuses on how soil pH, clay content, soil organic matter, and soil moisture levels can influence ammonia loss from urea ammonium nitrate (UAN) applied onto the surface without incorporation.
More recently, with emphasis on sustainable crop production, there are a number of tests that assess soil health. Some of the soil health tests such as the Haney Soil Health Tool (HSHT), which is adopted by USDA-NRCS, assess soil quality parameters as well as nutrient availability. The HSHT uses the H3A-4 extractant to estimate ‘plant available’ nutrients. The H3A-4 extractant simulates plant root environment by using organic acid plant exudates and has been touted as more representative of phosphorus availability. Some commercial soil testing laboratories offer HSHT and provide corresponding fertilizer recommendations. How does the test values and recommendations from H3A-4 relate to Mehlich-3 extraction? Publicly available information relating H3A-4 to Mehlich-3 extractable nutrients is limited. Continue reading