Monday, February 22, 2010

Learn something new from a soil analysis

Because students are working to expand the community organic garden to take up most of the space within the fenced area at the arboretum, we mailed off soil samples to the Timberleaf Soil people in California. The test called for a general application of colloidal rock phosphate to build the phosphorous reserve, along with various specific quantities of alfalfa meal depending on what crop we intend to plant. For example, 4.1 lbs. of alfalfa meal per 100 sq. feet is recommended for cabbage plants, but only 3.4 lbs/100 sq. feet for kale and 1.8 lbs/100 sq. feet for spinach. Alfalfa meal supplies nitrogen to the soil for plant uptake, but not all plants require the same levels of nitrogen in the soil. According to the Timberleaf soil analysis, nitrogen mineral recommendations are the most challenging due to the high degree of variability in soil types, climate, time of the year, soil moisture, biological activity, type of organic matter applied and the plant varieties. The best course of action is to keep records of the type and amount of nitrogen applied, the crop we plant, weather conditions, and the time of year applied. That way, you can compare results from various growing seasons over time and judge for yourself what your average nitrogen requirements are.
We are low in trace minerals zinc, manganese, iron, copper, and boron. In order to remedy this, the analysis recommends applying, per 100 sq. feet, 1.5 oz. of 36% zinc sulfate, 4.7 oz. of manganese sulfate, 12.9 oz. of iron sulfate, .7 oz. of copper sulfate, and 1 oz. 14.9% boron. Because boron can be toxic in larger quantities, it is important to pay attention to the measurements and split applications several months apart. Further ammendments include 7 oz. of potassium sulfate per 100 sq. feet and 2.5 oz. of 90-95% sulfur.

It will take an estimated 3-4 years to reach balanced soil fertility.
The organic matter content of the red clay under the grassy patch is only 2.1%. The desired organic matter content is 5-6%, so we will apply a healthy measure of compost prior to planting. The soil is acidic, with a pH of 5.5 and a buffer pH of 6.8

The soil test taught students about Cation Exchange Capacity (CEC). Cations, which include calcium, magnesium, potassium, and sodium, are all positively charged, or basic minerals. The CEC tells us the quantity of cation nutrients the soil can hold. Good soil structure, or "tilth", means exceptional capactiy to hold, store, and release nutrients in a biologically available way. Good soil acts like a sponge for air, water, and nutrients!
So, soil contains many clay and organic particles in it. These soil particles have many negatively charged sites on their surfaces, which attract the positively charged mineral cations, holding them loosely to the surface of the particles. The roots of plants can exchange hydrogen ions in return for these cations. The CEC tells us the sum total of negatively charged sites in the soil particles and express it as a number - so in theory, a 20 CEC soil can hold twice the nutrients of a 10 CEC soil. We have a CEC of 4.2, so the way to increase that is by adding compost, thereby integrating more organic material into the soil.

Sunday, February 21, 2010

Potatoes and Peas!

There were some beautiful organic little potatoes from California on sale in Publix about a month ago, so I bought two bags. I put one bag in my cupboard and forgot about it. Upon discovering the potatoes in my kitchen a week or two later, the tubers had already sprouted little "eyes", or buds. So I put a few on a kabob skewer and elevated them in cups of water. You can use any container for this, but recycled yogurt cups work quite nicely. A week or two later this is what you have! Students met at the arboretum this morning and we planted 16 potato tubers into a large, well composted bed that we prepared at the end of last semester.

Camille and Lizzy dug two trenches about 8 inches deep and 2 feet apart. They spaced each potato about 2 feet in the trench and alternated them with the potatoes in the other trench so that they are not exactly parallel in the rows. This saves space. Lastly, cover the tubers with compost and straw to prevent soil erosion and increase water moisture retention in the bed. These potatoes will not require much maintenance until the plants come up and start to bloom. This is the first time students have planted potatoes in this community garden, so we are all excited to see how they will like their new, temporary home.
Meanwhile, Matthew and Chelsea worked to complete installing the wire fence around the wooden fence. This serves multiple purposes. The wire fence will prevent rabbits and other critters from jumping into the garden and will provide trellis support for the peas and other vineing veggies. This activity works up a sweat!

Along the opposite corner of the fence, students already installed the wire trellis, so today we direct-seeded climbing sugar snap peas a few inches away from the fence so they can latch on to the fence when they are ready. After the row of peas, we inter-cropped a row of carrots with radishes. Carrots and radishes are good companion plants because while they can grow in the same space, they grow at different rates, so you can harvest the radishes just in time before the carrots begin to thicken up and need the extra space. In the 4x4 square-foot garden plots, our bush peas have finally made an appearance. The recent snow and cold weather made them delay in sprouting, but they have pulled through. The thick straw mulching might have been a help to them. The strawberries are still dormant, and we will soon say goodbye to the last few kohlrabi as we prepare that bed for the spring garden.

Students are experimenting with the effectiveness of double-digging. Along one side of the fence, the bed was double-dug and compost was integrated. Along the other side of the fence, the soil was not double dug, just turned over with a pitchfork and amended with compost. We planted the same vegetables along both sides, so we will see which do better, also taking into consideration any variation in sunlight exposure between the sides. The next beds we prepare will be double-dug and amended with colloidal phosphate and possibly greensand, and recommended in the results of our soil analysis done by Timberleaf Soil Testing.

In the greenhouse, the tomato plants are doing fantastic. The spinach, however, were very dry and clearly suffering because no one watered them on Saturday, so students soaked them for an hour in a warm shallow tub. This perked them up a good deal. This was a reminder that seedlings need to be watched every day, and we all need to help keep each other accountable for coming out when we say we will. If something comes up and we cannot make it to the garden, that is fine, we just need to call and let others know so that someone can go check that the seedlings have enough moisture.

This is am image of what you don't want your seedlings to look like. These spinach babies are lacking water, but a good soaking in a shallow warm tub zaps them back to life. Constant communication helps keep students accountable for staying organized and checking on the seedlings every day..yes even saturdays :)
It has been decided that we will no longer use peat pots because they dry out very easily and do not decompose in the soil very quickly.

The empty tray has marjoram seeds in it but they have not sprouted yet. The cabbage, lettuce and beet are all doing well, and we have started gradually exposing them to the outdoors by setting them in a shady spot for a few hours at a time. This will help acclimate the plants to the sunlight and wind before it is time to transplant into the garden.
Today, students planted 24 eggplant, 24 sweet red pepper, and 20 cayenne long hot pepper seeds in the greenhouse. The trays are on the heating pad because these nightshades germinate at an optimal temperature of about 70-75 degrees Fahrenheit. They will be ready to transplant into the garden after the last frost of the season, which we are estimating at April 15.

Tuesday, February 9, 2010

complications in the greenhouse - live and learn

The UA Arboretum greenhouses are full of life and fresh air. A greenhouse prevents sudden temperature change, providing seeds a head-start in their development and prolonging the growing season for a farmer, increasing the potential crop yield.

On Sunday, a group of students entered the Arboretum greenhouse to discover that a mouse had maneuvered his way into a tray of unsuspecting beets and eaten every last seedling! So, students reseeded that tray and secured it with two plexiglass sheets on top so that mice and rats cannot lift off the covers to feast on the tender shoots. The garden was too wet to do anything with the soil, but students harvested handfuls of salad greens and kohlrabi. When the ground is soaking wet, it is not wise to garden because soil compacts tightly when wet. Soil compaction means that the little air bubbles that occur naturally in good soil structure are destroyed. It is very difficult, if not impossible, for plant roots to penetrate compacted soil in order to receive the nutrients, air and water they need. Plants grow best in a well composted, spongy-like soil with adequate moisture, sunlight and air.

It rained early this morning, but students carpooled to the Arboretum at 9:30 am.
Another discovery in the greehouse. A tray of lettuce greens got “damp off” – which is a fungus that rots the base of the plant at the root, causing the little seedlings to simply keel over and die, even though the stems and leaves look perfectly healthy. Damp off will live in warm, still, and dark spaces, so the way to minimize risk is to allow plenty of air circulation, expose the seedlings to sunlight, and take them off of the heating pad immediately after germination to allow them to cool off in the greenhouse. Students left the seedlings on the heating pad with a protective cover on them for longer than necessary, resulting in “leggy” plants that look as though they are reaching for sunlight and cool air. It is important to monitor germinating seeds every day in order to be sensitive to their growth process and responsive to their needs.
As an extra precaution against mouse visitations, Mary Joe Modica, Director of the Arboretum, placed a mouse cage with peanut butter in it by the germinating table. We’ll see if it lures in any seed snatchers.

Matthew Bush, Natural Resources Management major, weighs down the seed tray cover with a glass sheet, preventing rodents from lifting off the cover to eat seeds.

As a safe but effective precaution against ants, students spread a thin layer of diatomaceous earth around the germination trays. Diatomaceous earth is a naturally occurring sedimentary rock that can be crushed up into a white powder. It’s structure is rough and abrasive, so ants avoid climbing on it, as it will cut them and hurt them.
As a safe but effective precaution against damp off, students milled some long fiber sphagnum moss to sprinkle over the germinating trays. This moss has an acidifying effect in its surroundings by taking up cations and releasing hydrogen ions. Damp off, the fungal infection, does not take well to these acidic conditions. We will also prevent damp off simply by removing the trays from the heat as soon as they germinate, giving them adequate air circulation, and taking care not to over-water (roots grow into air pockets in the soil, but when there is excessive moisture in the soil, it takes up all of the air pockets and the roots have no where to grow, resulting in root rot).

The new garden plan will include a 4 foot wide pathway making an “x” cross The new garden plan will include a 4 foot wide pathway making an “x” cross design through the middle of the garden for easy bed access and optimal space utility.