Mulch to be Desired

1. Mulch to be Desired A discussion of the mulching practices of members of the North Central District 3/15/2014

2. Summary Stuff • The idea to create this program was based upon an article read in an organic gardening magazine. It talked about the C:N Ratio and how different types of mulches can have significant impacts on the soil • In mid January , a survey was distributed to our NCD ARS members. 24 rosarians responded to the survey (thank you) • Additional information presented in this program is from “Teaming with Microbes” as well as various internet sites

3. What is Mulch? Mulch is simply defined as a protective covering spread around plants as well as on top of the surrounding soil • Mulches are typically categorized as organic or inorganic • Organic Mulch: derived from things that were once alive, which can be recycled back into nutrients by soil food web organisms. Examples include grass clippings, wood chips, and coco bean shells. Generally need annual replacement • - Inorganic Mulch: Stones, gravel, shredded rubber and similar material. They cannot improve soil fertility but can reduce weeds and are often used for aesthetic appeal. Generally last for several years.

4. What types of Mulch are used in the NCD? • Twenty two different types of mulch were identified; Most commonly reported included: • Compost • Wood Chips • Chopped Leaves • Coco Beans • Shredded Bark • Grass Clippings Others Mentioned: Pine Needles Landscape Fabric Plastic Stone Coco Beans with Rice Hulls Ground up tires Rice Hulls Leaf Mold Horse Manure Shredded Cedar Triple Ground Hardwood Colored wood chips Rye Straw Mushroom Compost

5. What are the benefits of Mulching? • Top 4 Benefits Identified by recent NCD survey: • Weed Control • Keep Ground Moist • Visual Appeal • Fortify/Provide Soil Nutrients • Other Benefits Mentioned: • Improve soil structure • Prevent fungal disease • Winter protection • Keep ground cool • Protect irrigation system from damage and sun degradation • Easier to work in the garden (less mud on the shoes)

6. Is one mulch better than others? Favorite Mulches Rosarians responded with a variety of products! Wood Chips Coco Beans with Compost Wild Rice Hulls Weed Free Shredded Chopped Leaves with Compost Coco Beans Horse Manure Coco Beans with Rice Hulls Black Colored Wood Chips (Enviromulch) Rye Straw Cypress Mulch Pine Needles Compost Leaves/Bark Mulch/Compost Shredded Oak Bark Hemlock FREE There was no clear favorite mulch identified; Some folks use different mulches for different plants or areas in their yard. Clearly, many different types of mulch are used and seem to meet the needs of the gardener -- or do they??

7. A Closer Look Composting is the transformation of organic material (plant matter) through decomposition into a soil-like material called compost. Invertebrates (insects and earthworms), and microorganisms (bacteria and fungi) help in transforming the material into compost. Composting is a natural form of recycling, which continually occurs in nature. Not all composts are the same. Leaf mold is a form of compost produced by the fungal breakdown[1] of shrub and tree leaves, which are generally too dry, acidic, or low in nitrogen for bacterial decomposition. While not high in nutritional content, it is a great soil conditioner. Pine straw mulch Pine straw is a pine needle that has fallen from a pine tree. Pine needles are used in flower beds as a ground cover for landscaping. Pine straw helps insulate the soil from temperature fluctuations and will not move with heavy rains. Pine straw is excellent on hills and slopes because the needles interlock after spreading and keep the pine straw from moving. Pine Straw is also referred to as Pine Needle Mulch and does not exhibit all of the problems of a hardwood mulch.

8. What impact does mulch have on the soil? • Organic mulches will decompose over time, feeding soil microorganisms and releasing small quantities of nutrients • Recent studies released by the Ohio State researchers, suggest that the type of organic mulch applied will impact soil fertility and plant health • A good mulch works wonders in imparting soil food web benefits in to the soil. • Worms also pull mulch material underground, resulting in worm castings, better water retention and improved airation.

9. Plants are in Control! Microbes secrete nitrogen in form of ammonium

10. Plants are in Control! Mulches can create a feeding frenzy by the fungi and bacteria, and if not matched by additional activity by the microbes, can result in the nutrients being tied up and not available to plants. This is also referenced when disscussing the C:N ratio Using the right mulch can establish dominance of fungi or bacteria

11. A bit about Fungi and Bacteria Dr. Elaine Ingham at Oregon State University began publishing results of studies in the 1980’s that identified a correlation between plants and their preference for soils that were fungal dominated or bacteria dominated In general, perennials, trees and shrubs prefer fungal dominated soils, while annuals, grasses and vegetables prefer soils dominated by bacteria Acids produced by fungi as they begin to dominate lower the pH and greatly reduce the bacteria If you can cause either fungi or bacteria to dominate, or provide an equal mix, then this will help the plants get the kind of nitrogen that they prefer which will help them thrive

12. Bacterial vs. Fungal Mulch A mulch of aged, brown organic material supports fungi; a mulch of fresh, green organic material supports bacteria Where and how you place the mulches also plays an important role. Mulch laid on the surface tends to support fungi, while mulch worked into the soil tends to support bacteria Bury most mulch and bacteria will have an easier time. If it is on the surface, fungi will dominate the decay activity for a while because it is easier for them to travel from the soil to the mulch If you wet and grind mulch thoroughly, it speeds up bacterial colonization. Bacteria need moist environments or they go dormant. Coarse, dryer mulches support fungi activity. If you want fungi activity, use brown leaves or wood chips; don’t pulverize them or wet them much. Place them on the surface

13. Green and Brown Mulches • The most readily available green mulch is fresh grass clippings, which contain all the necessary sugars to attract and feed bacteria • Avoid grass taken where weed killers an pesticides have been applied • Don’t pile grass clippings too thick or it will create an anaerobic condition, interfering with the bacteria you are trying to impact • Most popular brown mulches are made from leaves saved each autumn; These will support fungal dominance unless ground up to fine pieces • Leaf mulches grow more fungi (or grow them faster) than wood chips • Peat moss is often used as brown mulch; Peat is biologically sterile and should be mixed with other materials to introduce some microbiology • Pine needles make a great brown mulch, but only after they have aged a bit as they contain terpenes, volatile chemicals that are toxic to many plants; Cedar chips also contain high levels of terpenes • Wood chips, shredded or chipped bark and sawdust are great brown mulches and work fine, especially if aged or mixed with organic nitrogen (i.e. green grass)

14. The C:N Ratio(as reported in organic gardening) In order to decay, mulch requires air, water, carbon, nitrogen ; If there is abundant carbon in mulch but not much nitrogen, a ratio of 30:1 or greater, then the decaying microbes use up the nitrogen in the mulch, and once gone, will take nitrogen from the soils touching the mulch (also known as nitrogen robbing) Organic Materials and their C: Since it is primarily bacteria that tie up nitrogen in the soil, consider using “brown” mulch practices to minimize the impact Others indicate that this impact is only in the top layers of soil and not where the roots of our roses are.

15. Other Comments/Notes • Adding a layer of mulch greater than 3 inches may end up blocking moisture and air, smothering fungi • Do not put mulch snug up against stems or trunks, this can cause microbial decay of the plant itself • Mulches can excel when they are used in conjunction with compost. Put the compost down first then cover with mulch. Compost organisms will inoculate the mulch, and begin to decay it as well. • You can actually grow your own microbes by soaking fresh grass clippings, alfalfa, hay or straw in water for three to four days. Pour this on your mulch and you will increase the nutrient cycling power . (Remember our “tea bags” from last year??) • Mulch can prevent weeds because the mulch ties up the nitrogen and it is not available to the shallow weed roots. Plant roots are deeper and not as impacted.

16. Resources to Find Mulch The #1 Source: Local Rose Society!!!!!!! Is Your Rose Society Providing this Product?? Other Sources Mentioned: • Make my own compost • Leaf Mold from Landscape Trucking Company • Horse Farms • City Recycling Centers • Gardener Supply Catalog • Local Garden Centers • The Farms Compost, Caledonia, WI • Mississippi Topsoils, Coldspring, MN • Leftovers from Winter Protection • Triple ground hardwood – Ericsons landscape Supply/Union Grove

17. Problems with Mulch? • Formation of mold on top of mulch • Nondegradable materials (tires, stone, wood chips) require upkeep to remove leaf matter • Compost alone doesn’t prevent weeds • Grass clippings/coco beans that are too thick – result in water runoff • Coco beans wash away in heavy rains • Landscape fabric makes it harder to add more roses • Stone is impossible to work with when adding new roses • Leaves didn’t hold moisture • Mushroom compost may encourage blackspot and mildew • Drawback in spring when need to pull back mulch to apply fertilizers

18. Other Comments from Responders • Be mindful of what mulch can do to soil and plants • Use mulch that doesn’t need to be hauled off – creating another problem • Be aware of cost and labor to install & how often needs to be replaced • Weed garden well before application – apply Preen for weed control • Remove mulch in fall and reapply in spring • Master gardeners discourage use of bark for perennials or roses • Landscape fabric doesn’t seem to provide enough soil airation and moisture • Weed Daily • Place deep irrigation system under mulch • Be sure to wait for soil to warm up before applying • I put down a layer of worm poop before the mulch goes down • Cultivate mulch annually or it will get compacted and retain less moisture

19. Summary Comments • People use a variety of mulches to meet their needs • The type of mulch used can impact the soil composition and nutrition • When applying mulch in your garden this year, consider the benefits to your soil, which ultimately impact the health of your plants • Different mulches will encourage more fungi or bacteria. Plants have a preference for one or the other (Roses prefer more fungi). • Fungi rich soil will provide the nitrogen in usable form for our roses • You may want to use different mulches in different parts of your yard or gardens • - The management of nitrogen in your garden is fundamental to success. Understanding the impact of mulch is beneficial