Recent Updates

2021 Corn Grain Hybrid Tests in TN – Now Available

Results from the 2021 TN corn grain hybrid trials are now available at search.utcrops.com/corn-grains. Seventy-one hybrids were evaluated in small plot replicated trials (REC) at seven locations and fifty-four hybrids were evaluated in ten to twenty locations as non-replicated large strip plots (CST).  A summary of hybrids that were in the “A group” (not statistically different from the top yield within each test) in either the REC or CST trial is given below. Continue reading

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Integrating Cover Crops in Nitrogen Management

Cover crops can supply nitrogen (N) to the soil for the subsequent cash crops and this nitrogen credit may be successfully integrated into N management. The challenging question is how much of the N supplied by cover crops is available for the next cash crop. Unfortunately, there is not a simple answer to this question since several factors influence the N availability from cover crops. There are two primary considerations if the goal of planting cover crops is to contribute N to the soil: the proportion of species in cover stand and the timing of cover crop termination.

The proportion of species in the established cover stand is important because different species have different effects on N. Depending on the species of cover crop planted, soil N may be removed or supplied to the soil. Grass cover crops (e.g. cereal rye, annual rye, wheat, oats), which are referred to as “scavengers” take up nitrates from either residual N fertilizers or organic matter decomposition. So, grasses do not contribute a whole lot to the soil N since not all of the scavenged N is available for the next growing season. An established cover stand comprised of all or mostly grasses will not provide any significant N benefit. Hence, the recommended N rate for the cash crop should not be reduced. In contrast, legumes (e.g. clover, winter pea, hairy vetch) supply additional soil N through biological N fixation. A well-established legume cover crop stand would supply sufficient N to warrant reducing the recommended N rate. UT currently recommends a 60 to 80 lb N credit for a well established legume cover crop that has reached early bloom.

Generally, most growers plant multispecies of cover crops with less than 50% of biomass being a legume. Since legumes supply N, a good percentage of legume in cover stands is required to maximize plant available N for the next cash crop. A study in TN has shown that 30% legume biomass in cover stands can supply up to 43 pounds of N per acre when terminated late. It is critical to evaluate a stand of mixed species cover crops to determine actual legume proportion if some N credit is desired.

The second consideration is the timing of cover crop termination. There is a thin line between growing cover for extended periods to maximize plant available nitrogen (PAN) and yield loss of the cash crop. Generally, if the goal is to maximize PAN from a well-established legume stand, late termination may be a preferred choice. It is worth pointing out that late termination would result in delayed planting and increase the potential for yield loss of cash crops such as corn. If the legume is terminated early, those plants are smaller and have less time to fix N which can be released back into the soil. In contrast, well-established grass stands must be terminated early, especially if growing a cash crop with high N demand (e.g. corn). This strategy will not necessarily supply N but, rather prevent N from being tied up in the soil.

In summary, unique challenges presented by rising N fertilizer costs may present opportunities to rely on cover crops to meet some N need for the next cash crop. However, to integrate cover crops in N management, the cover crop should consist of at least 30% of established legume in the cover crop stand and should be terminated at early bloom. Currently, UT only recommends a N credit of 60-80 pounds per acre of plant available N following a single species well-established legume cover crop that has reached early bloom.

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Dicamba-Resistant Waterhemp Confirmed in Tennessee

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Results from greenhouse experiments and in-field research this summer confirm that our state now has dicamba-resistant (DR) waterhemp. Moreover, our survey of weed escapes this fall sponsored by the Tennessee Soybean Promotion Board has found that waterhemp has spread quickly. Continue reading

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Dr. Seth Byrd: Cotton Outlook after a Freeze Event

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Calls concerning our forecast have been steady.  In order to get some insight into how to handle closed bolls some have remaining in the upper canopy prior to a freeze, I reached out to Dr. Seth Byrd in Oklahoma.  Dr. Byrd has served in both Texas and Oklahoma and has years of experience tackling this issue when an impending freeze event is in the forecast.  His comments are below.  Special thanks to Dr. Byrd for this contribution! Continue reading

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Managing Input Price Risk

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Posted by Tyson Raper on behalf of the author, Dr. Aaron Smith

It’s a challenging time for crop producers to manage input price risk. Input prices for fertilizer, crop protection (chemicals), machinery, fuel, labor, rent, and insurance are up substantially compared to last year at this time. Additionally, availability and timeliness of delivery are a major concern. Fertilizer prices highlight this dramatic increase in the cost of production (graphs above). Most common fertilizers have more than doubled compared to last year. As such, producers are seeking strategies to reduce input costs. Two recommendations, as a starting point, are soil sampling (know what you’ve got) and crop selection (know current relative cost and revenue relationships for commodities produced on your farm). Unfortunately, there is no “silver bullet” to mitigate rising input costs and availability concerns. So, producers will need to be creative in their approach and consider numerous strategies. Continue reading

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A new tool for utilizing Mid-South soybean variety trial data

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Which soybean variety is best suited to my region? State variety testing programs provide critical research to help answer that question by evaluating hundreds of soybean varieties every year across multiple locations within a state. But what if we think beyond the bounds of our state borders when it comes to variety evaluation? While a single state alone provides valuable data, our growing regions often cross state lines. A location in West Tennessee may share more similarities to sites in East Arkansas than it does to East Tennessee. By combining variety testing data across multiple states, we can create a more robust dataset that allows us to better predict which varieties are best suited to specific regions and growing conditions. Continue reading

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