Plants need at least eighteen essential nutrients to grow and develop. Deficiencies of any of these essential elements can cause reduced crop yield and quality. For instance, we know that a high protein content in bread flour is essential for quality bread baking while low protein contents in flour is critical for quality cake baking. Aside from genetics, soil fertility management has a big impact on protein content and types of protein in the wheat we use for baking bread or cakes as well as all other crops. Plant proteins contain, among other elements, nitrogen and sulfur. So having adequate supplies of nitrogen and sulfur in the soil for the crop being grown will affect the development of protein in plants. Sufficient amounts of these two elements will guarantee high grain protein content and bread baking quality, while low nitrogen and sulfur availability in soil can lead to low grain protein content and cause poor bread baking quality. Often plants exhibiting nitrogen deficiencies develop yellowing on their lower leaves.

Bottom leaves of tomato turning yellow often indicate nitrogen deficiency. Photo by dmp, UConn

A common problem that we often see in our vegetable gardens is blossom end rot in tomatoes, peppers and summer squash. When conditions are right, the fruits of these plants develop quickly and each new cell that is formed requires calcium. When not enough calcium is available to plants either because there is not enough in the soil or there is not enough moisture to move the calcium from the soil into the plant roots, a calcium deficiency develops and expresses itself as blossom end rot. Also, if you have seen internal brown spot in the potatoes growing in your garden, you may also want to check the calcium level in your soil. Typically, you would do this by checking the soil pH. Since limestone (calcium carbonate) is used to raise the pH as well as supply calcium, if your soil pH is in the 6s, there should be sufficient calcium present in the soil so if you are seeing blossom end rot, it would most likely be due to insufficient watering.

Blossom end rot on tomato. Photo by dmp, UConn

Potassium is another nutrient that crops like potatoes need in high quantity. Potassium not only influences potato tuber yield and size but also potato sugar concentration, hollow heart disorder, even coloring after cooking. Sufficient availability of micronutrients, such as zinc and iron, are important for plants growth and nutrition values. These micronutrients are also essential for human health, and you can often find them in supplements.

Tomato with possible potassium deficiency. Poor locules and thick, mealy walls. Photo by dmp, UConn.

How do we know if our soil is sufficient in these nutrients? Soil testing can give you an idea of your nutrient sufficiency levels in the soil and plant tissue testing can tell you if your plant is accessing these nutrients. Some potential issues that could impact nutrient uptake by your plants include low pH, excessive amounts of another nutrient, poor soil structure and drainage, compaction, and improper watering. For macronutrients, such as phosphorus, potassium, calcium and magnesium, soil testing is sufficient while for micronutrients, such as zinc, copper, boron, manganese and iron, we recommend testing both your soil and plants if a nutrient deficiency is suspected. If you observe poor plant growth and good plant growth in the same garden or field, it’s best that you take soil and plant samples from both areas and get the samples analyzed separately so that you can compare nutrient levels in these areas. Keep in mind that many diseases have symptoms that mimic nutrient problems so it is always a good idea to send photos of the problems you are seeing to the horticulturists at the UConn Home & Garden Education Center (ladybug@uconn.edu).   

Is this a disease on cucumber or nutrient deficiency? Photo by dmp, UConn

For soil testing for garden crops, you can take soil samples at any time of the year, but fall is best. While taking samples before seeding, transplanting of annuals, and greening up of perennials is important to ensure timely application of fertilizer and soil amendment to provide your crops with sufficient nutrients during the whole growing season, keep in mind, that samples submitted in the spring take longer to process because of the higher volume. If samples are submitted in late fall rather than in early spring, recommendations are likely to be identical and if amendments such as limestone, which takes 6 to 18 months to work, are needed, they can be added in the fall so they can start working. Any fertilizer would be added in the spring before planting.

If you notice deficiency symptoms in your plants, it is important to take quick action to try and diagnose the problem and apply fertilizers, soil amendments, or change your cultural practices to deal with nutrient deficiency issues. Although your plant’s health may have declined because of nutrient deficiencies, a rescue application of nutrients can alleviate symptoms and put it on the path to good growth.

Plant tissue testing is primarily recommended for commercial growers because at the UConn Soil Nutrient Analysis Lab, there are no recommendations for home gardeners, only commercial vegetable and fruit growers. For commercial growers submitting samples, it is critical to sample the correct plant part at the right growth stage. This is because the tissue test sufficiency ranges that are use to compare your samples are established for that specific plant part and growth stage for a given crop. For example, ten uppermost recent fully developed trifoliate leaves should be sampled from green beans in summer, fifteen compound leaves adjacent to the inflorescences should be sampled during midbloom for field tomatoes, and twenty-five mature leaves from new growth should be sampled during flowering – fruiting should be sampled for peppers. Prior taking your soil and plant samples, please visit University of Connecticut Soil Nutrient Analysis Laboratory https://soiltest.uconn.edu/ for guidance on when and how the samples should be taken. Feel free to call the lab at (860) 486-4274 if you are considering submitting samples for plant analysis. UConn also has a Plant Diagnostic Lab that can culture plants for diseases.   

Another important thing to remember regarding soil and plant tissue analysis is that it is important to send your samples to your local labs. This is because different labs use different testing procedures that are calibrated for soil types specific in their region and the plants grown in these specific environments. The standard sufficiency levels established are therefore different by state and by region. For example, there are many different soil test procedures being used in the US for soil phosphorus test, however, only modified Morgan testing procedure is used for CT soils due to specific characteristics of our soils in CT.

The bottom line for home gardeners and growers is to do your best to ensure your plants receive the correct amounts of nutrients as well as water to be able to supply the nutrients to our plants. Routinely monitor your plants for insects, disease problems as well as nutrient issues. We are here to help you so feel free to contact the UConn Home & Garden Education Center (www.ladybug.uconn.edu) or UConn Soil Nutrient Analysis Lab (www.soiltest.uconn.ed) if you need help or have questions.

Haiying Tao, Ph. D. Dept of Plant Science LA, UConn

The last few years certainly have been a challenge for many of us.  One unexpected consequence of the pandemic? Many who were quarantined at home decided to become gardeners.  Seed companies reported a boom in sales during the pandemic and, unlike other trends, (zoom cocktails, sourdough starters or dress shirts with pajama bottoms), it looks like gardening is here to stay.  To those new to gardening and to those more seasoned gardeners, we are here to help you every step of the way.  

We are the UConn Home and Garden Education Center, which is made up of three branches; the education center; the soil nutrient analysis laboratory; and the plant diagnostic laboratory. The education center is your first point of contact, where you will be greeted by horticultural consultants Dennis Tsui, Pamm Cooper and Marie Woodward.  Our mission is to answer your questions about anything related to home gardens and landscapes.  Our goal is to give you the best science-based response. In addition, we often rely on our other two branches for information, but that’s just the start of the services they provide. 

Dawn Pettinelli

Good gardening begins with knowing all you can about your soil, and The UConn Soil Nutrient Analysis Laboratory, headed by Dawn Pettinelli, Associate Cooperative Extension Educator, provides home gardeners a means to test the fertility of their soil and, through a comprehensive report, receive environmentally sound fertilizer and lime recommendations. 

Dr. Nick Goltz

Identifying the cause and nature of plant problems is often the key to maintaining healthy gardens and landscapes, and that’s where Dr. Nick Goltz, plant pathologist, comes in. He heads the Uconn Plant Diagnostic Laboratory and is an expert in diagnosing plant problems including diseases, insect pests and abiotic causes.  Dr. Goltz has a passion for plant health and integrated pest management, (IPM).  He especially enjoys working with homeowners to find holistic and comprehensive solutions for any plant problem they may have.

The three branches of the center are available to gardeners year-round.  To access our services, you can reach us by phone, (860-877-6271), by email, (ladybug@uconn.edu), or you can visit the center the Radcliffe Hicks Arena, 1380 Storrs Road, unit 4115, Storrs, CT. Our hours are Monday- Friday 8:30am -4:30pm.

Collecting and Submitting Samples

One of the most common questions we are asked is how to collect samples that are of good diagnostic quality.  Each laboratory website has detailed instructions on how to do so.  For the Soil Nutrient Analysis lab, there is a page with instructions on how to submit a soil sample at:

Soil Sampling Instructions

The plant diagnosis laboratory has a form with instructions on how to collect plant sample at the bottom of the submission page: 

Plant Submission Form

Samples can be mailed in or brought into our center during our office hours, (see above).

Emailing us with a question?

If you’re emailing us with a question or problem, it can be helpful, (but not necessary), to include a few photos with it.  This can help us determine our response. 

To learn more, you can visit our website: http://www.ladybug.uconn.edu/ where you will find the latest news, blogs and fact sheets about all things for your home garden.  We are ready to help make your home garden a success year after year. 

This year is going to be different! I say that every year. It always seems that as I sit inside in the early evening (it gets so dark so quickly at this time of year), next year’s gardening seems so easy. I envision a thriving, beautiful garden in the summer with a bountiful harvest in the fall.  Then, reality happens.  It never seems to work out as we thought it would. Last year was a disaster, in many respects, due to the never ending rainfall. Connecticut recorded it’s third wettest summer on record. There were some crops, however, that seemed to do well.  Anyway, we cannot control nature, but we can manage our time and efforts. This is a list of my New Year’s resolutions for the garden. See how many can help you as well.

I have to say I am off to a good start. The warm weather, defined by me as non-frozen ground, has really inspired me. I started a big tool reorganization project in my garden shed and hung a board that will hold all my tool holding hooks. This should make it easier to find what I need right away, saving a lot of time, and less frustration when I go in that shed, as I will no longer trip over the tools! Daylight is limited, so I will have to finish this project another day.

The New Year’s Resolutions are off to a good start as the author planted all his garlic, even if it was in January. Photo by mrl2022.

Another thing we frequently overlook is a soil test. This is really the simplest thing a gardener can do to ensure success, but we so frequently do not think about it (at least until April). We also need to give the lab time to do the tests, and then get the results back to us (usually a week except during spring rush when it might take 3). In a warm January where the ground is not yet frozen (may be by the time you read this), this may be the perfect time to gather our soil samples. The second most important part to a soil test is following the recommendations for soil improvement. If you are deficient in some nutrients but do not add them, anticipate plants may struggle. Give yourself the time needed to source and purchase the proper amendments. 

A portion of my soil test results from three years ago showing nutrient levels and liming recommendations. It may be much different for your yard, but the only way to know is to test. Photo by mrl2022.

My next resolution is to open more ground. I always wonder where my limit will be. There is more space to garden left untapped. If I am careful with my time, I can open up more ground to plant. Now is actually a great time to start prepping the soil and mapping out new gardening areas. Remember, the ground is not frozen and the snow has not fallen (yet). It does look like we will be getting really cold though. This unseasonably warm time cannot last forever. At the very least we can plan out where the new plots will go and measure the square footage of our new patch. This information can help us know how much of something we need to purchase/ add based on the recommendations from our soil test. 

Probably the most important resolution is to weed when the weeds and plants are small.  Weeding when the ground has not frozen is easy, compared to later in the year when the weeds are tall and the roots are deep. If you do not weed until your plants are overgrown, the weeds have already competed with your plants for nutrients, and may have even shaded them out, and/or stunted their growth. If this situation is left unchecked, we may lose our plants. 

Mulching can significantly reduce and almost eliminate weeds.  Mulching should be done right after planting.  Leaving that ground uncovered will only encourage weed seed germination.  If not done, you will only have to pull all the weeds out by hand, and then mulch later on.  Why make all that extra hard work for yourself?  In the mean time, your plants will have their growth negatively impacted.  Do yourself, and your plants, a favor and weed in the early spring or even during winter thaws.

My next resolution is also off to a good start – planning. Over this past weekend, I did a complete inventory of the seeds I have, the seeds I need, and updated my list by what performed well in the garden (or not). I also tried to save some money by cutting out the species that did not seem to perform well. This also saves some time, because why plant some varieties that just do not seem to do well in the garden?  Right now, I am in the process of figuring out my ground preparation and planting schedule. This should save me some time in the long run and help ensure successful crops. 

One example of poor planning last year was my sweet potato crop. I did not have the soil ready and when they came in, they sat for too long before planting. To make matters worse, they seemed to not have come in that good so they were already stressed. Whether it was the excess rain or too long of a holding time before planting, I experienced a total crop failure. This will not happen again this year.

The other thing that can happen, and even more so to the experienced gardener, is that you acquire your plants too quickly, and there is a build up of plants waiting for placement in the ground. I had this happen once a few years ago with my tomatoes. They so needed to go into the ground, were suffering nutritional deficiencies, and were highly stressed. Now, I knew how to fix this situation, but growth and production certainly were impacted. Try and pace yourself, and plant what you get as soon as possible.

A small fraction of the seeds ordered by the author for the 2022 gardening season. Seeds do not last forever so be careful of using old seed. Photo by mrl2021.

I think some additional time and attention is due after the crops are planted. I really want to make sure that I water at correct intervals. Last year, I think I only had too water twice at the beginning of the season.  After that, it started raining and never stopped. Many times, I have people ask me about how much or how often they should water. That is a difficult question to answer because it will depend on soil structure and composition. Fine-textured silty or clayey soils tend to hold moisture while sandy soils tend to dry out. One inch per week is a general guideline, but you really might want to poke your figure into the soil to see how wet it is below the surface. I am always surprised at how a dusty, dry surface can be nice and moist a half inch down. There are also moisture meters you can buy to help with this task and provide a numerical value if you prefer.

In general, plants benefit from some drying between waterings. In addition to the one inch of water per week, it is better to put a lot of water down at once, rather than short, frequent waterings. The thought is that the roots will go deeper if watered less frequently, and therefore the plant will be better able to tolerate dry periods. A rain gauge can assess how much water your garden received. This is a great way to measure how much water your sprinkler puts out during a given period of watering time as well.    

Watering and precipitation can affect soil nutrient levels. Too much water can leach nutrients from the garden. This may mean you would need to fertilize more frequently. Organic fertilizers are often more resistant to leaching than conventional ones. Once again, your soil test will dictate how much fertilizer to put down. You cannot just take a guess and hope for the best. The manufacturer of your choice of fertilizer will make some recommendations for how often to put it down. Without a soil test, follow the application suggestions on the fertilizer package.

While plants may grow without additional fertilizer, they are typically more productive, show better disease resistance, and are less susceptible to insect pressure when they have proper nutrients. I have found that many times I get busy during the growing season and either forget to fertilize at the proper interval, or I knew I should, but did not. This seems counterproductive as the whole reason for planting crops is to enjoy the harvest. A few missed fertilizer applications can severely impact your harvest. Adding soil amendments, such as compost, can supply plants with many of the nutrients they need. Do keep in mind that the nutrients present in a compost depend on the materials used to make it, so not all composts are created equal. Soils amended with compost can be tested every 2 to 3 years and if nutrients are lacking, they can be added before planting. Unfortunately, because of its complexity, UConn does not offer compost testing. However, once compost is incorporated into the soil, a composite sample of the mixture can be sent to the lab to determine pH and nutrient levels. I resolve to be more diligent this year in my application of fertilizers (if needed).      

A portion of my soil test results discussing fertilizer amendments. Photo by mrl2022.

The last two resolutions go hand-in-hand. I resolve to harvest my crops at the right time. This is another “easier said than done” situation. It is better to harvest cherry tomatoes right before a big rain to avoid cracking. Green beans are best harvested young, or they can get tough and stringy.  Zucchini is really a wonderful vegetable when small, but gets a tough skin and is really seedy when they gets large. Get it while the picking is good or you might need to compost the crop.

Many times, the rains affect our ability to harvest. Keep an eye on the forecast and try and build some time to harvest into your week.

The second side of this coin is food preservation. There is nothing better than being in the middle of a long, cold winter (they always feel like they will never end – except for this year when it just is starting), and having a nice dinner made with vegetables harvested from your garden. The down side is that it takes a lot of time to prep and preserve the literal fruits of our labor. When it is warm and sunny, who wants to stay inside and can, blanch, freeze, etc.? Maybe set up an outdoor workstation? 

This year I am really going to try and stick to my New Year’s resolutions. If I do, I should have the most amazing garden, and plenty of food to eat and share. We all know that life happens and not everything will get done perfectly. I think the most important part of this story is that not everything will go perfect, not everything will get done on time, but most things will. If the occasional watering does not get done on time, a fertilizer application goes down a little late, that is not a very big deal. If waterings are missed repeatedly, or fertilizer applications (based on soil test results) are regularly missed, the plants will not grow very well and production will be severely impacted. Try to not miss the same things all the time.

 Do your best. Enjoy your gardens and the fruits of your labor!

Raise a glass of that canned tomato juice or peach shrub to the New Year! 

Matt Lisy

The days are getting visibly shorter. I cannot seem to get most of what I have to do done before it is too dark to see. Too bad I did not have time to install those new yard lights… Although the cold weather has not really hit yet, most people are not really thinking about gardening anymore.  I have been thinking a lot about gardening lately. This is probably one of the best times to get some projects done in the garden. Many of the items I discuss are actually for next year’s garden!

Although most people complain about the leaves in the yard, I just smile (then complain under my breath when I lose a whole day to leaf duty). Leaves make the most wonderful compost, especially if given a little attention along the way. It is best to chop the leaves into small pieces, if possible, otherwise they tend to mat when they get wet. I would also recommend placing them in an active compost site where the microbe populations are at their strongest. Mixing in a little mature compost into the pile will help as well. It is best to turn the compost pile often. I will do this every few weeks. You would be surprised how the heat of decomposition keeps the pile warm even in when the ground is frozen! I love to see the steam come off a freshly turned pile.  Not only does the turning process help aerate the pile and therefore aide in decomposition, it also helps more thoroughly mix the ingredients. There is a whole science to composting, but I always recommend to use what you have, and add as much to it as possible. Kitchen scrapes, including egg shells, can go a long way to enriching that rotting leaf pile.

The author’s large leaf pile half way through the yard leaf clean up day. This will be turned multiple times during the fall, early winter, and spring. Photo by mrl2021.

Another thing people generally do not think about this time of year is a soil test. Soil analysis labs are inundated with soil tests each spring. In reality, you might be better off testing in the fall.  You will probably get your results back sooner. In addition, you will have more time to make any amendments, and to plan out the ideal crops for that plot. The one amendment that comes to mind first is limestone. Connecticut soils, in general, are low in pH. Many gardeners do lime in the spring, but it is actually better to lime in the fall and mix that in so the soil is ready in the spring. Certain crops, like brambles (blackberries and raspberries) actually prefer this method of liming. 

It is important to note that limestone is not required each spring, and the amount you need to apply, if any, is determined by a calculation based on your current soil pH and the optimal pH needed to grow a specific crop. Luckily, most soil testing places will do the calculations for you.  All you need to do is send in the soil and they do the rest. Again, I want to emphasize that the most important thing to do is test the soil first. I so frequently run into people who just lime because they think they should. If a test is not done, you might be wasting your money. If your pH is correct and you lime, now it will be too high. If your pH is too low, you might not be putting enough lime on. Also, there to two different types of lime – calcitic and dolomitic. Their chemistry differs depending on the amount of calcium or magnesium in the mix. Your soil test results can indicate surpluses or deficiencies in those nutrients, which will help you to select the correct lime for your situation.  Collecting soil samples is not hard to do, but it does take a little bit of time.  The efforts will pay off when you are able to tune in the chemistry going on in your garden soil. 

A large area covered by a tarp to kill the weeds and grass. This will be pulled up and limed this fall, and a cover crop will be planted. Photo by mrl2021.

Another fall time garden activity that often gets overlooked is taking stock of crop performance.  So many times, we think we will remember what did good and what did not, but we forget when we go to order seeds or buy our plants the following year. It is helpful to write down that information as it will help you with your seed orders on a cold winter’s night! This is also a good time to plan out, measure out, and maybe even start to prepare the soil in a new garden site. Time is so precious in the spring, and it always seems like I get behind on gardening. The weather certainly throws us off schedule. This is why it is so important to try and save time by doing as much as possible now.

These Zinnias and Cosmos did great in my wife’s bouquets. Knowing what variety I planted is important for ordering seeds next year. Photo by mrl2021.

Don’t forget to harvest as well. Many times we get tired of going out to the field, or the time gets away from us and the sun is down before we know it. Make sure you get your potatoes and any shell beans that are remaining harvested. I have had a great year with volunteers. These are plants that came up from seed and were not planted intentionally by the gardener. Many times the seeds somehow make it through the winter and germinate. This past weekend I just harvested three pumpkins, and a big bowl of cherry tomatoes – all from volunteers. There are also some really big squash growing out the side of the compost pile that I have to get as well. 

Lima beans waiting for harvest. Photo by mrl2021.

My final suggestion is to weed. Normally this is the chore we hate the most, but even more so when it is a cold, wet, fall day. This will make life easier in the spring. Leaving some small grass clumps that came up this year will turn into large, hard to pull grass mounds by the spring. Remember, the goal is to free up time and make life easier next spring. It will be here before you know it so, as the old saying goes, “make hay while the sun shines!”

Can you find the horseradish in amongst the weeds? Photo by mrl2021.

Matt Lisy

As most of you are probably already familiar with, the University of Connecticut is home to the UConn Soil Nutrient Analysis Laboratory. This lab is staffed by Dawn Pettinelli, the manager, and myself, the technician. We also have a few part time and student employees throughout the year that help with the receiving, spreading, and sieving of soil samples; among other things. We offer an array of tests designed to help homeowners, community gardeners, farmers, etc… maximize the efficiency of their soil to produce the greatest yields in whatever plant or crop they are growing, from silage corn to turf. We can test for soil organic matter content, textural fractionation, soluble salts, Nitrogen, and Carbon. We also provide tests for plant tissues and corn stalks. However, our most vital and popular test is the Standard Nutrient Analysis. This is a relatively comprehensive test that allows us to make limestone and fertilizer recommendations. We check the pH, add a buffering agent and then retest the pH. From there we are able to determine the soils capacity to resist the change in pH, this allows us to make an accurate and precise limestone recommendation, in lbs/1000 square feet, or lbs/acre, depending on the desired crop production. The second part of the Standard Nutrient Analysis is the actual nutrient content. Soil samples are analyzed for micro and macro nutrients; Potassium, Calcium, Phosphorus, Magnesium, Aluminum, Boron, Copper, Iron, Manganese, Zinc, and Sulfur. Samples are also screened for Lead. Using the nutrient results, we are able to make fertilizer recommendations based on what is being grown. We give results in N-P-K format, and also provide organic alternatives.

We get calls year round from customers asking if they can submit a soil sample, and the answer is always yes! You can submit a soil sample any time of the year, we receive soils from throughout the country (although we have to be careful of areas under certain quarantines). Generally, it only takes around a week from when we receive a sample for us to send out the results. As you might imagine, Spring is an extreme exception. We are so busy and backed up with thousands of soil samples right now, we are expecting a 3 week turn-around time. We understand that everyone is eager to get their hands dirty and work on their lawns and gardens, but waiting until Spring to submit soil samples isn’t the best idea.

sample1

The current line of samples waiting for analysis. J.Croze

We often recommend that customers take and submit soil samples in the Fall! Soil sampling and testing in the Fall is better for all parties involved. For starters, we offer a discount on the Standard Nutrient Analysis, if you submit 10 or more samples we only charge you $8 per sample opposed to $12. However, there are more practical reasons to submit a Fall soil sample. It’s easier! The soil is generally going to be easier to work with in the Fall than after a wet Winter during the first few weeks of Spring. This will help you obtain soil samples that are a more accurate representation of the area you are interested in. Every year around this time we get dozens of zip-lock bags that are filled with soaking wet soil, dripping everywhere. A Fall soil test also allows you more time to think about what amendments you might want to use, and is the perfect time to apply limestone and fertilizers in preparation for a busy and productive growing season. Applying limestone in the Fall ensures that it has enough time to raise your soil pH to whatever the optimum range is for what you plan on growing. My personal favorite reason for submitting a Fall soil sample is that we are less busy! You’ll be happier because your results will only take a few days, and we’ll be happier because the phone won’t be ringing off the hook with customers wondering where their results are! You can obviously submit a sample whenever your heart desires, but I advise you to consider sampling in the Fall. For those of you currently waiting on results, I appreciate your patience! Happy gardening!

-J.Croze

The UConn Soil Nutrient Analysis Lab tests for and analyzes multiple soil parameters; but none as critical, and as often overlooked, as pH. Soil pH plays a crucial role in the growth of vegetation planted, as well as ground water quality. Before we start talking about soil pH, I think it is a good idea to try to define what exactly pH is, and how it is determined.

When most of us think of pH, a pool probably comes to mind. I remember growing up, watching my mother apply different chemicals to our pool, and impatiently wondering why I had to wait to go swimming. She would tell me that she was adjusting the pH of the water to ensure it was safe to swim in. The basic understanding is that pH is tells us how acidic, neutral, or alkaline something is. To get a little more technical, pH is the measurement of the activity of Hydrogen Ions (H+) in an aqueous solution. The equation for determining and quantifying pH is:

pH = -log10 (aH+)

(aH+ = Hydrogen Ion Activity in Moles/L)

We express pH on a logarithmic scale of 0-14, where 0-6 is considered “acidic”, 7 is “neutral”, and 8-14 is “basic”.

pH range

(Image from: http://www.edu.pe.ca/gulfshore/Archives/ACIDSBAS/scipage.htm)

Mineral soil pH values generally range from 3.0 – 10.0. There are numerous factors that determine soil pH including climate, parent material, weathering, relief, and time. Texture and organic matter content also influence soil pH. Most Connecticut soils are naturally acidic. Nutrient availability is directly influenced by pH with most plants (with some exceptions) thriving at pH values between 6 and 7. A majority of nutrients are available within this range.

pH vs nut avail-1

(Image from: http://www.pda.org.uk/pda_leaflets/24-soil-analysis-key-to-nutrient-management-planning/)

Our lab measures pH using an 1:1 soil-to-DI water ratio. The saturated soil paste is mixed, then is analyzed using a glass electrode and a pH meter. We calibrate our meter using 2 solutions with known pH values, 4 and 7. We use these values because we expect most Connecticut soils to fall within this range. Once the initial pH value is obtained, a buffering agent is added. In our lab we use the Modified Mehlich Buffer. A second pH reading is obtained, and from these two values plus crop information, we are able to make limestone and/or sulfur recommendations.

The Buffering Capacity of a soil is the resistance it has to change in pH. Soil buffering is controlled by its Cation-Exchange-Capacity, Aluminum content (in acidic soils), organic matter content, and texture. A soil with a lot of organic matter and clay will have a higher buffering capacity than one with little organic matter that is mostly sandy.

If the soil pH is lower than the target range for a particular plant, limestone would be recommended. Whether you use pelletized, ground or granular limestone, the application rate would be the same. Once the target pH is reached, a maintenance application of 50 lbs/1000 sq ft would be applied every other year to maintain it.

If the soil pH is higher than desired, sulfur recommendations are made. Typically only powdered sulfur is available locally but granular sulfur could be mail ordered. Aluminum sulfate can be substituted for sulfur and used at a higher rate. Check out this list of preferred pH ranges for many common plants.

Monitoring your soil pH is essential to ensure that it is falling within the range best suited for the vegetation you are growing. The Standard Nutrient Analysis performed at our lab gives you a pH value, a buffer pH value, a lime/sulfur recommendation, available micro & macro nutrient levels, and a fertilizer recommendation. For more information on pH, you can contact Dawn or myself (Joe) at the UConn Soil Nutrient Analysis Lab (www.soiltest.uconn.edu)!

Test, don’t guess!

Joe C.

 

lime-bag-homedepot

Bag of Lime

Many Connecticut residents spread limestone on their garden beds and lawn as an annual ritual. Why do we do this? Some do it because their parents did it, or the guy at the garden center told them to and sold them the limestone. How much should be purchased and applied is another mystery to most. The real answers of limestone’s why, how much and when lies in the science of soil.

Soil is made up of sand, silt, and clay. The percentage of each of these three determine the soil’s texture, which will determine how the water will move through it, or hold on to moisture. More clay equals wetter soils; more sand, better drainage. The sand, silt and clay are tiny pieces of rock, broken off of bigger pieces over much time by weathering. The rocks that makes up much of Connecticut has a naturally low pH in the 4.5 to 5.5 range. Other areas of the country and world have different rocks with different pH ranges. Acid rain falling onto the ground lowers pH levels, as does the action of organic matter decomposing which produces organic acids. Even the normal function of respiration by plants mixing oxygen and water together produces carbonic acid in the soil. More acid equals lower pH. No wonder why we need to test, monitor and fight the natural tendency of our soil to stay in a low pH range.

Most plants we want to grow require a pH range of 6 to 7. This means we have to change the pH to grow plants like grass, tomatoes, peppers, squash or garlic by adding limestone which raises the pH level. The only plants consistently happy with our native range are native plants! They have evolved in the local soil. This is why blueberries, oak trees and mountain laurel fill our forests and wild areas. Pines are another tree preferring our lower pH.

Why do the grass and vegetables prefer the 6 to 7 pH range? Because more of the nutrients that these species of plants need are available when the soil pH is in that range. The easiest way to think of pH is it is a measurement of the amount of hydrogen ions in the soil. The more hydrogen ions, the more acidic the soil is. The pH of the soil affects the availability of all plant nutrients. Just as plants have ideal moisture and light requirements, they have a preferred pH range as well.

The pH range numbers 0 to 14. The middle is neutral at 7. Pure water has a pH of 7. 0 is acid or bitter; 14 is alkaline or sweet. Old time farmers used to taste the soil to determine if it was bitter (acid, low) or sweet (high, alkaline). I am glad we have pH meters and laboratory soil testing equipment now!

0_________________________________________7_____________________________________14 Acid (Bitter)                                                                           Neutral                                                                  Alkaline (Sweet)

Soil pH levels also affect other life in the soil such as insects, worms, fungi and bacteria. The soil is alive with more than just plants. It is an entire ecosystem sustaining many life forms all interacting with each other. The pH level is probably the most important place to start when trying to provide the best environment for whatever plants you are growing.

Have your soil tested for pH and nutrient levels at the UConn Soil Nutrient Laboratory www.soiltest.uconn.edu. Have the $12.00 basic test for Home Grounds and Landscapers done. Forms and directions are on the website. We will be offering free pH only tests at the CT Flower Show February 23-26, 2017. A half cup of soil is needed. If you don’t have snow covering your ground now, go gather some soil now and hold it until the show. Once you know the pH of your soil, we can tell you how much limestone to apply in the spring. Fall is the best time to put down lime as it needs about six months to fully react and change the soil pH. Never put limestone down on frozen or snow-covered soil to avoid it running off to areas you didn’t intend to lime, like the storm drain. Limestone will not soak into frozen soil.

ph-meter

pH Meter

-Carol Quish