The addition of organic material to soil can improve its fertility. But to fully understand why, we must go to the atomic level. This week’s guest, retired horticulture prof Debbie Flower, will give a primer on soil chemistry, including cation exchange capacity and the effects of positive and negative charges.
Joe Lamp’l: 283-A Primer on Soil Chemistry: How Electrons and Protons Influence Fertility and Soil Moisture
Debbie lives in California, in the Sacramento region. She has worked nationwide for wholesale and retail nurseries and university cooperative extension and experiment stations. She has lived in New York, New Jersey, Arizona, Oregon, Nevada, and Oregon. She holds a bachelor of science in plant sciences from Rutgers University, New Jersey, and a Master of Urban Horticulture from UC Davis, California. She has also served twice as the California Association of Nurseries and Garden Center’s president.
Debbie is a gardening expert with a wide range of horticultural and gardening knowledge. But her soil chemistry expertise brought her on the podcast this week. She discusses how negatively and positively charged ions affect how water, soil particles, and organic matter behave in soil.
I want to mention my new book that was published last month before I continue with our conversation. You can find it online or in local bookstores. It is called ” Vegetable Gardening: Your Complete Guide to Growing an Edible Organic Garden from Seed to Harvest.” This book contains new information and insider tips to help you improve your gardening skills and overcome challenges.
Organic Vegetable Gardening, my new Online Gardening Academy (TM) Premium Course, is scheduled for release in 2023. Register for the waitlist.
Meet Debbie Flower
Debbie was raised gardening with her grandmothers, and she loves the outdoors. These two things contributed to her choice to go into horticulture. She persevered despite several setbacks in her academic and professional career that were beyond her control.
She met her husband while working at a Puerto Rico agriculture experiment station as part of a student exchange. She says, “I worked on sugar cane, pigeon peas, and mangoes there.”
She then moved to Tucson, Arizona, where she worked with pistachios. Then she moved back to Portland, Oregon, where she worked for another agricultural experiment station. They were working on composted sewage sludge being used as a media amendment to grow plants. While living in Portland, Oregon, she became a certified Master Gardener.
Debbie excelled at computers and worked with corporations involved in mine reclamation projects in Wyoming and Montana. Her family moved to Reno, Nevada, where she began her graduate studies in horticulture.
She says, “These environments are all very different.” “I have always cultivated gardens wherever I go, but I needed to learn more about these environments and figure them out. This was very frustrating. Every time I began, I felt like I had returned to kindergarten. The result is that I now understand the general terms more than the specifics. “If I understand what I am looking for in general, and then I get specifics, it’s easier to figure out.”
Unfortunately, Nevada University closed the program after she had 19 credits in a 30-credit program. Her academic advisor told her to attend the University of California, Davis. This prompted her family to move to California. UC Davis only accepted five credits, so she needed to catch up. She earned a master’s in urban horticulture in 1992 and began working for Sacramento County Cooperative Extension. But the state ran out of money, and she lost her position.
Debbie then taught horticulture in a vocational training school for adults. “We maintained the landscape and had a greenhouse.” It was very hands-on. We fixed lawnmowers, started seedlings, and planted them in the greenhouse. We had plant sales. “I did this until my children needed me more at home.”
She then switched to part-time work. However, she held three jobs simultaneously: teaching computer applications, working at a retail nursery, and for a nursery that served the whole city. She became a professor in several community colleges and did hands-on work.
She continues to be active in retirement. She is a regular guest on the Sacramento-based podcast ” Basics of Gardening with Farmer Fred” for beginning gardeners. She says they try to cover relevant topics for any gardener, no matter where they live.
Sand, Silt & Clay
Good soil comprises 45% minerals and 5% organic material, and 50% air and moisture. Minerals in soil are divided into three types: sands, silts, and clays.
Debbie explains how sand is classified strictly according to particle size in a soil laboratory. The particle size of sand is the largest, while that of clay is the smallest.
All of these are pieces of broken stone. She says that the rock has weathered and broken into these pieces. “Now, certain mineral fragments will only be certain sizes.”
You can tell what minerals are in the particles by their size. The particle sizes also indicate different chemical properties. Debbie says that one of the characteristics is how well they can hold water. The larger the particles are, the less they can have of water. Sand drains quicker than silt or clay.
Debbie used a large jar filled with balls to demonstrate when she taught classes. Water quickly finds its way into the spaces between the ball when it is poured in, like water from a hose or rain. The water in a jar filled with pennies has fewer spaces to move around, so it moves much slower.
Water flows through the soil in a downward direction. Water moves along the edges.
Two hydrogen atoms are found in each molecule of H20.
Debbie says, “The hydrogens have a positive charge, and the oxygen has a negative charge.” Imagine that if you hold your thumb and index finger at a 105-degree angle, one hydrogen atom is at each tip, and oxygen is at the base of the fingers.
Water sticks together because the positively charged hydrogen attracts another water molecule’s negatively charged oxygen atoms. If you drip moisture onto a flat surface, it will bead together.
Debbie explains that “water can also adhere to other things which are charged, and all soil particles have different negative charges to different amounts.” The amount depends on the surface area of each particle. Sand is the largest particle with the smallest surface area per unit. Clay has the largest surface area.”
