Berlese Funnel Test

An experiment was done to collect and count the macroinvertebrates in our soil sample. A 2 liter bottle was cut just above the label, inverted, a piece of wire (plastic) mesh was inserted at the base of the inside of the nozzle, and soil was added to just about 2 cm above the top of the inverted, cut, top of the bottle. ~20 mL of ethanol was added to the bottom of the base of the cut bottle, the top was inserted into the base, and the soil was set to let dry under a heat lamp for approximately one week. The bottle under the lamp, or the initial final product for beginning the experiment, looked as such:

A close up of the soil:

After about one week, the bottle was taken out from under the light and the organisms found in the soil were identified after being poured into a petri dish. This yeilded:

Also included in the following analysis were organisms picked out during previous experiments that we wanted to be sure were counted, as shown here:

In our sample, we found approximately two sowbugs (or woodlice), three earthworms (one small, two fairly large), five to ten mites, and two millipedes (one small and one fairly large). Sowbugs and earthworms are generally considered good for the soil, as they produce compost and overturn soil. Sowbugs can sometimes be negative if in masse as they can sometimes feed on cultivated plants, and can indicate dampness problems, but are generally considered good or harmless. Mites are often considered good as well as they break down decomposing matter or organisms, similar to worms but they act more as a catalyst, beginning the process. Millipedes are also good for the soil as they too break down plant matter and other organic material. These results are moderately consistent with other groups, at least those with more silty soil like ours. The presence of millipedes is different than many groups but the rest of the results are fairly consistent.

- Andrew

Soil Fertility Analysis

For this experiment, tests were conducted to find the levels of pH, nitrogen, phosphorus, and potassium in our soil sample. The first test was for pH, which for our soil sample was found to be ~6.0, meaning the soil is slightly acidic. Next was the test for nitrogen, which resulted in a low amount of such being availible in the soil. After this was phosphorus, the amount present was found to be between 9 to 14, meaning only a marginal amount was availible to plant life. Lastly, potassium levels were measured and found to be moderately high, meaning the amount of potassium availible was close to excessive. The experiment looked as such while in progress:

After being shaked, the test tubes looked like this (note: this image is from directly after shaking and timing to let set began; results derive from color changes produced after the set amount of time indicated by each test in the kit). From left to right: pH, nitrogen, phosphorus, potassium:

Based on these results, nitrogen and phosphorus were found to be the low or lacking nutrients in our soil sample, while the pH was more acidic but still moderately balanced and an excess of potassium was discovered. It is normal for wetland type of environments (the habitat our soil sample is from) to have low nitrogen levels, but a marginal amount of phosphorus is a concern as normally wetland soil is very good at holding phosphorus and this could hinder the soils true usefulness.

The ideal pH range for plants in the type of area our soil sample was collected from (a wetland) is around a 6.0, so for this to be the pH is ideal for plant growth. The plants there looked very healthy and have increased in abundance over the last few years, so the soil is correct for the types of foliage that need to grow. 

- Andrew

Soil Porosity

A porosity test was conducted to determine the ease with which oxygen, nitrogen, and other necessary elements can work their way through the soil into the root zones of plants. For this experiment, a 250 mL beaker was filled to 200 mL with moderately dry soil and gently tapped down. A 100 mL graduated cylinder was also filled to 100 mL. The water was slowly added to the soil until it began to pool slightly at the surface as such:

A small amount of the excess was put back into th graduated cylinder as it was too flooded. This resulted in our remaining water becoming cloudy but still a accurate representation of the amount left:

The remaining water was measured to be at ~62 mL remaining:

To find the soil porsity therefore, you subtract the original 100 mL by what is left, 62 mL, and get 38 mL as what was used. You divide this by the amount of soil used, 200 mL, and multiply by 100 to find soil porosity, or (100 - 62) / (200) x 100. This yeilds a soil porosity of .19, or 19%.

- Andrew

Soil Moisture

A test was conducted to to figure out how much water was in our soil sample, or the percent of our soil that was actually nothing but water. A small sampling of soil (~1.5 cups) was placed in a tray made out of aluminum foil:

This sample was measured to weigh 27.8 grams when the aluminum was zeroed out and subtracted:

The sample was then heated in a drying oven for ~24 hours to remove excess water content, and when weighed again was found to now only weigh 10.5 grams:

To find the percent of moisture, or the percentage that was water, you subtract the mass of the soil before being heated (27.8 grams) by the mass of the soil after heating (10.5 grams), divide it by the original mass of soil (27.8 grams again), and multiply that by 100, or (27.8 - 10.5) / (27.8) x 100. This yeilds a percent of water of ~62.2% water, meaning that well over half the soil consisted of water. There does appear to be a correlation between soil moisture and texture based on the test results- silt was found to generally be very wet and not ribbon very well, as high moisture would explain and silt does.

- Andrew

Soil Collection

The soil for our experiment was taken from Old Mill Grove Park, a sports complex converted to wetland/prairie ~15 years ago. The soil therefore is very silty with much organic matter present. It was found here:

Closer up, it looks like this:

There are many roots present as well as leaves and other plant matter such as grass and twigs on the surface. Most of th particles are fairly small -silt-sized- with some larger rocks and others thrown in. Very little clay or sand was present, so it is hardly a loam. Next to this spot is a gravel pathway going through the park, so it is possible that pueces of gravel and rock could have been mixed in. Seen here:

There were also mant earth-dwelling bugs, worms, and other larger life visible. There is some clumping of silt but the particles are sill relatively small.

- Andrew

Introduction

Welcome to Kasia and Andrew's magical soil blog! I hope you enjoy the enthralling experience that is reading about our quests through the world of experimentation with soil samples. To start off, some background knowledge is required. Soil is the upper layer of earth in which plants grow; a black or dark brown material typically consisting of a mixture of organic remains, clay, and rock particles. Soils consist of four major components: minerals (inorganic compounds), organic compounds, water, and air. The relative proportions of these four soil components vary with soil type and climatic conditions.  

There is a stark difference between what most people would consider"dirt" versus what is "soil." Dirt is what you find under your fingernails. Soil is what you find under your feet. Think of soil as a thin living skin that covers the land. It goes down into the ground just a short way. Even the most fertile topsoil is only a foot or so deep. And soil is more than rock particles; it includes all the living things and the materials they make or change. 

The formation of soil happens over a very long period of time. It can often take thousands of years to form! Soil is formed from the weathering of rocks and minerals. The surface rocks break down into smaller pieces through a process of weathering and is then mixed with moss and organic matter. Over time this creates a thin layer of soil. Plants also help the development of the soil by attracting animals, and when the animals die, their bodies decay. Decaying matter makes the soil thick and rich. This continues until the soil is fully formed. The soil then supports many different plants and other life. 

Soil texture refers to the size of individual soil particles. This affects how water and air flows through the soil. Large particles mean that water can drain easily, while small particles hold water longer. Sand features the largest particles. Water can travel freely through this type. Plants that love water may have a difficult time surviving in sand, since the water drains quickly. Sand can come in standard, coarse, fine and very fine grades. Meanwhile, silt particles are smaller than sand, but larger than clay. Silt can hold some nutrients, but clay has the smallest particles. Since they are so small, they are close together in the soil, which can make it difficult for water to travel through. However, clay often has a loam has an equal amount of sand, silt and clay soil particles. This is considered the optimal soil for many plants since it features the positive characteristics for each type of soil texture. Color and texture both indicate which minerals are broken down and present in the soil. Depending on the rock that weathered to create the soil, it can be either very fertile or not so fertile. 

The soil pH is a measure of the acidity or basicity in soils. pH is defined as the negative logarithm (base 10) of the activity of hydronium ions (H+ or, more precisely, H3O+) in absolution. It ranges from 0 to 14, with 7 being neutral. A pH below 7 is acidic, while above 7 is basic. Soil pH is considered a master variable in soils as it controls many chemical processes that take place. It specifically affects plant nutrient availability by controlling the chemical forms of the nutrient. The optimum pH range for most plants is between 5.5 and 7.0, however many plants have adapted to thrive at pH values outside this range.

The soil present in Lake Zurich is primarily of a more silty composition, as we live in a temperate forest area with high nutrients. Soils of Hawaii consist of a loam that is fairly even with all three types of soil, Georgia would have a silty composition much like here, and Arizona would have a sandy composition. Georgia may also include some sand at is touches the Atlantic Ocean. Therefore, Lake Zurich would have a soil composition similar to that of Georgia (including the sand as we are moderately close to Lake Michigan) as well as some similarities to Hawaiian soil, but would be considered drastically different than that of Arizona where the climate is so different.

A farmer should be very interested in soil analysis because his main job is to grow crops on his property. Soil testing is an important management practice on all farms, whether growing vegetables for fresh market or pasture for livestock. It’s nearly impossible to determine what a soil needs to be productive without a soil analysis. There are many types of soil analyses available depending on what information you are seeking.  The most commonly requested analysis is for nutrient content, though you may wish to know what organisms are working in your soil, if there are pesticide residues or determine the particle size analysis.

 

We hope that you enjoy our blog as we document the process of determining just how awesome or horrible the soil in Lake Zurich truly is!

- Kasia