Category Archives: Soil

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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The New UTcrops.com !!!

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If you haven’t noticed, our UTcrops.com website has gotten a facelift.  You may not recognize it when you first visit us at  https://utcrops.com/.  However, it’s organized similarly to the old version.  I’m sure there are a few bugs that need to be fixed, but take a look!  This site gives you ready access to essentially all UT resources related to row crop production.

 

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Visual Symptoms: A Handy Tool in Identifying Nutrient Deficiency in Row Crops

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Generally, a nutrient deficiency occurs as a result of low soil nutrient levels. However, prevailing environmental conditions, soil properties, and growth conditions may restrict nutrient uptake and induce deficiencies in crops even if soil nutrient levels are deemed sufficient for optimum yield. For example, low or high soil pH, soil compaction, and excessively wet or dry soil may prevent nutrient uptake. A handy diagnostic tool to identify nutrient deficiency in crops is via visual symptoms. In some instances, this tool may not provide a definite diagnosis of the nutrient status of the plant. Keep in mind that there are other conditions that are cable of inducing symptoms that closely resemble those of nutrient deficiencies. Visual symptoms should be corroborated with tissue and/or soil testing. Adequate knowledge of visual symptoms and tissue testing may help guide corrective actions in-season or preventive action in the following season to avoid yield loss.

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Virtual Milan No-till Field Day … Available Now!

Follow the link below to experience the 2020 Milan No-till Field Day at your own pace! You can watch an entire tour by clicking on its name, or just one presentation by clicking on a specific title.

Please note, all links will open in a new tab. Closed captions are available by clicking the “CC” button on the right side of the video’s play bar.

Research Tours

 

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Soil fertility and nutrient management practices survey

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I am Nutifafa Adotey, University of Tennessee’s Soil and Nutrient Management Extension Specialist. A thriving and productive land for subsequent generation is of uttermost importance to every farmer, rancher, or grower. This survey is designed to gather brief but valuable information on some basic production practices in Tennessee. This information will help with the accurate delivery of innovations or interventions on soil fertility that caters to the needs of producers in Tennessee.

Kindly take a few minutes to fill out this survey if you are a producer or share this information with other producers in Tennessee. The survey can also be taken on mobile devices such as the smartphone or tablet. I have contracted with QuestionPro, an independent research firm, to field your confidential survey responses. I would appreciate your feedback in our online survey. Your survey responses will remain confidential and secure. Data will only be used to help build a robust soil and nutrient management extension and research program.

The survey is available at https://utk.questionpro.com/t/AQQL2ZgzJA

I appreciate your trust and look forward to serving you in the future.

Please contact nadotey@utk.edu with any questions.

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Minimizing Nitrogen Loss in Row Crop Production Using Nitrogen Stabilizers

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Nitrogen (N) fertilization is a costly operation for most row crop producers. Consequently, it is important to implement best management practices (BMP) available for N fertilizer application in order to be profitable. The problem with N fertilizers is their potential to be lost through different N loss pathways: ammonia volatilization, denitrification, and leaching. Spring of 2020 has been generally wet and if this weather pattern continues, farmers should have no problem receiving incorporating rain, minimizing risk for ammonia volatilization from surface-applied at planting N. In TN, most row crop producers split-apply N, with the majority of N fertilizer applied as a sidedress which is closer to the period of high N demand. Since a large portion of N is applied as sidedress, there is the greatest risk for N loss depending on management practice as well as soil and environmental conditions. Continued wet weather might support the use of nitrification inhibitor type products in wetter soils. This blog addresses N stabilizers as a tool to minimize the risk of N loss and ensure that N is available for crops during the period of high demand. Continue reading

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Corn and Cotton Producers’ Prevented Planting Decision

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Federal crop insurance programs have a prevented planting provision that can protect producers from the financial losses and risks associated with not being able to plant the intended crop within the desired planting period. Revenue Protection, Revenue Protection with Harvest Price Exclusion, Yield Protection, and Area Risk Protection insurance policies pay indemnities if producers were unable to plant the insured crop by a designated final planting date or within any applicable late planting period due to natural causes, typically drought or excess moisture. This post highlights several components of those provisions and provides a few examples.  

Kevin Adkins, Graduate Research Assistant, Department of Agricultural and Resource Economics, University of Tennessee

**Christopher N. Boyer, Associate Professor, Department of Agricultural and Resource Economics, University of Tennessee 302-I Morgan Hall Knoxville, TN 37996 Phone: 865-974-7468 Email: cboyer3@utk.edu **Corresponding author Continue reading

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