Saturday | April 25, 2015
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Making healthy soil out of rocks and ash

Ask a farmer or gardener in Kona about their soil and they’ll tell you, “We don’t have soil.” Living at the south end of the newest island in a chain created by volcanic action, leaves us with a lot of pahoehoe, aa and some volcanic ash. Better known as rocks and dust, our soil needs all the help it can get.

Of course, there are pockets of deep soil here and there, mostly caused by landslides of forest soil or preserved efforts of Native Hawaiian farmers. Most growers want to learn ways to improve their soil because they know healthy soil means healthy plants, which means better produce with less work.

Research indicates soils with balanced nutritional content yield more nutritious crops. Experienced farmers know soil health can translate into less pest and disease problems and better production. Many farmers spend time soil building before they plant as an important step toward success. Soil nutrition researchers and knowledgeable farmers can teach us a lot.

Probably the best indicator of healthy soil is the number of critters present. Healthy soil contains a large and complex community of organisms. Many gardeners and farmers are unconsciously killing those critters and their soil by regularly applying herbicides, pesticides and chemical fertilizers. Soil that is alive needs to be an attractive place for life to thrive. The critters you want to encourage include helpful microbes, fungi, worms and naturally occurring compounds that are produced as organic matter breaks down.

Current soil building advice is based on millennia of experience. During the early 19th century, farming began to move away from traditional wisdom. Chemical fertilizers became available in the mid-1940s, partly as a result of the availability of nitrogen-rich compounds no longer needed for the war effort. Driven by the desire for higher yields, many growers started using these chemicals to supercharge their plants while using others to fight the pests and diseases that followed. Today, however, many growers are eschewing these practices and returning to traditional ways with new knowledge and understanding.

Many credit the work of Masanobu Fukuoka, a Japanese farmer who wrote “The One-Straw Revolution” in 1978 with helping them understand the value of more natural ways of growing food. Fukuoka observed the ways plants thrived in nature and chose to integrate those naturally occurring systems into his farm. Using natural farming and organic gardening techniques was essentially a conscious return to traditional ways. Today, we can add new research and information about soil building to traditional practices and knowingly create high quality, healthy soil without killing it with chemicals.

Integrating compost into the soil and top dressing with mulch are among the traditional practices gardeners and farmers are increasingly employing to improve their soil. Compost and mulch can be created inexpensively and with little effort. Even small-time gardeners can compost waste and collect cuttings, clippings and leaves to top dress their beds.

Though natural systems can be highly successful, it is human nature to continually seek ways to make improvements. Recent soil research offers lots of information on natural ways to increase important factors like nutrition, taste and shelf life without significantly reducing production.

The pursuit of quantity is slowly being replaced by the pursuit of quality. The ways to grow the best crops possible start with the soil.

Soil nutritionist Jana Bogs has spent many years exploring the relationship between healthy soil and nutrition. She has developed a system that relies on soil and plant tissue testing to reveal deficiencies that she can then recommend natural ways to remedy. Her Beyond Organic Growing System focuses specifically on improving soil as a way to improve the nutritional content of crops. You can learn more about Bogs, her theories and her system at beyondorganicresearch.com.

The Kona County Farm Bureau decided to offer local farmers an opportunity to learn more about her system as a way to help farmers improve their crops. Her presentation is scheduled for next weekend at Tropical Edibles Nursery.

Tropical gardening helpline

Cindy asks: My monkey pod tree is consuming the area around it. The canopy is approximately 40 feet in diameter and 20 feet tall. I love the tree, but it needs to be trimmed. How shall I trim it, and when is the best time to do it?

Answer: Monkey pod trees can get very large. You will have to prune it often if you want to control its growth.

In Hawaii, most trees can be pruned lightly at any time of the year. When performing a more extensive pruning, the general rule is to prune when plants are in their dormant or resting period. This is usually a period preceding a time of active growth so the wound will heal rapidly. Late winter or early spring are good times, allowing the cuts a long time to heal before the following dormant period or “winter.” The University of Hawaii College of Tropical Agriculture and Human Resources says “Deciduous plants (such as monkey pod), which drop their leaves before flushing, are best pruned late in the dormant (bare) cycle.” The publication “Pruning Landscape Shrubs and Trees” is available at ctahr.hawaii.edu/oc/freepubs/pdf/L-8.pdf. Check it out for more pruning advice.

Monkey pods are generally considered nearly maintenance-free and do not require pruning except in cases like yours when you want to control growth. When pruning, start by removing branches that are dead, diseased or broken from the canopy. Then you can proceed with the more extensive pruning throughout the canopy.

Because of the size of your tree, you might want to get some estimates from professional tree trimmers. Most professionals are certified arborists or work with one. They will know how to best prune your tree and will have the proper equipment to do it efficiently and correctly. Ask lots of questions to be sure you find someone you are confident will give you the results you want.

This is a link to a publication on the monkey pod or rain tree, agroforestry.net/tti/Samanea-raintree.pdf. You’ll learn lots at this site, including the mature size of the tree.

Email plant questions to konamg@ctahr.hawaii.edu for answers by certified master gardeners. Some questions will be chosen for inclusion in this column.

Diana Duff is a plant adviser, educator and consultant with an organic farm in Captain Cook.