With climate change, extreme weather conditions and increased weather volatility are on the rise. With that comes drought, including extreme drought, and major storms. Just this week, DC issued a level two Drought Alert, which calls for water-saving measures both inside the home and outside in the garden.
One proactive way that home gardeners, landscapers, and farmers alike can fight drought is adding organic matter to improve their soils. Organic matter is proven to increase the water-holding capacity of soils of all textures, whether sandy, silty or clay-based. Obviously, sandy soils with their large pore spaces and lower cation exchange capacity (CEC) lose water faster, but all soil types can benefit.
According to the US Department of Agriculture, a one percent increase in organic matter in an acre of soil (measuring a foot depth down) translates to an additional 25,000 gallons of water retained. This is bringing soils up to 4 to 6 percent organic matter content is often suggested for landscaping and turf establishment. In agricultural scenarios, organic matter conservation through, for example, leaving crop residue on the surface, are recommended, as are the addition of organic matter sources like biosolids, manure and/or compost.
Research from the US Department of Agriculture and Appropriate Technology Transfer for Rural Areas has illustrated that organic matter can hold from 10 to 20 times its own weight in water; however, the characteristics of both the organic matter source and the soil can affect the amount of water held.
In 2016, I oversaw greenhouse trials for Bloom to test this out in application. As the results table below indicates, by adding Bloom in increasing amounts, both clay- and sand-based soils experienced increased in water holding capacity and hydraulic conductivity (water percolation) as well as decreased soil bulk density (weight per unit volume of soil). Reducing soil bulk density in turn reduces compaction and enables soil to better absorb, hold and percolate water.
Bloom Addition to Two Regional Soils
| Sample ID | Water Holding Capacity (mls/100g dry) |
Hydraulic Conductivity (inch/hr) |
Bulk Density Saturated (g/cc) |
Bulk Density Dry wt. (g/cc) |
|---|---|---|---|---|
| 100% Clay, 0% Product | 23.3 | 4.9 | 1.277 | 1.036 |
| 90% Clay, 10% Product | 24.8 | 5.6 | 1.268 | 1.016 |
| 80% Clay, 20% Product | 31.7 | 22 | 1.253 | 0.951 |
| 100% Sand, 0% Product | 5.27 | 18.1 | 1.688 | 1.603 |
| 90% Sand, 10% Product | 6.31 | 22.63 | 1.629 | 1.532 |
| 80% Sand, 20% Product | 9.19 | 45.26 | 1.487 | 1.361 |
5/2016, Alexander / Shields
Research from this trial indicates several ways in which Bloom can be a boon in drought conditions, namely:
- Bloom’s ability to absorb and hold water. Water-holding capacity increases as larger volumes of Bloom are added. This is because Bloom swells to absorb water, assisted by its cation exchange capacity (a measure of nutrient holding capacity), which helps the soil cling to positively charged water.
- Bloom’s ability to aggregate soil, creating larger pore spaces, where both air and water can be held.
- Bloom’s organic matter content, which possesses a lower bulk density (weight per unit volume) than soil particles (sand, silt and clay) and therefore helps to reduce the bulk density of the overall soil mix (again, that reduces compaction and enables soil to better absorb, hold and percolate water).
- The addition of organic matter has also been shown to reduce soil crusting, which enhances the absorption of water during rain events.
So, the addition of high-quality organic matter can improve soil characteristics in a way that improves water acceptance, water-holding capacity and percolation, all of which benefit the establishment and production of various crops and landscape plant species.
There are some other distinctive drought-fighting compounds Bloom has been demonstrated to stimulate, according to a team of researchers led by professor Greg Evanlyo, who conducted greenhouse trials using Bloom. In a report published in Crop Science, the researchers concluded that “biosolids application improves leaf anti-senescence hormones, osmoprotectant, and antioxidant metabolism to increase grain yields, especially under drought stress,” conclude the researchers.
Taken together, there are clearly numerous benefits to applying a product like Bloom or an Remember, before increasing irrigation on an on-going basis, develop a plan to increase the organic matter content of your planting soils. It’s not a panacea that solves all drought situations, but it is an excellent first line of defense.
Ron Alexander is President of R. Alexander Associates, Inc. a consulting company specializing in product development for organic recycled products. He is a Horticulturist (Delaware Valley University) with 40 years of experience working with biosolids-based, compost and other organic recycled products. Ron is also a technical consultant and has completed various product trials with Bloom products.
