Bee-safe, climate friendly and effective fertilizers
Bee-safe? Huh? Several readers asked if organic fertilizers are safe for bees. Generally speaking, pesticides can do far more harm to bees, organic or not, but could even organic fertilizers reduce the potency of pollen and nectar? We know that pollen of some common species contains as much as 30% less protein than it did in 1842 (as tested in dated herbarium specimens). While there’s no hard data on garden plants, numerous studies show that organically grown crops provide more and better quality nutrients than those grown with chemical fertilizers.
Sadly, in some European countries (including Holland and England), agronomists estimate that ‘conventional’ farms might only yield 100 more harvests. The continuously farmed soils are so depleted that even extra artificial fertilizers can’t make up for the loss of humus and soil biota that keep soil healthy, since chemical fertilizers don’t nourish soil as organic fertilizers do. Even home gardeners may experience dwindling harvests when they grow the same crops in the same places year after year. Crop rotation, cycling root crops and greens, heavy producers like tomatoes and less hungry squash or beans, can mitigate soil depletion, but harvesting and clean up removes nutrients stored in that removed plant material. Composting in place is optimal, but turning leftovers into compost and spreading it generously is also good practice.
Fertilizers are enticing because they seem to promise better returns for less investment of time and care. In the real world, living plants still require frequent care and attention, especially in a hot, dry year. Fertilizers can be good for the garden, but it’s important to make wise choices and use them correctly. For instance, time-release fertilizers are sold for everything from annual baskets to lawns, promising that plants will be fed all season. However, time-release fertilizers are triggered by soil temperatures in the 70’s; spread in February or March, they’re inert until the first hot day in spring, when those pellets can all release at once. Plants can be badly burned by excess fertilizer in hot, dry weather.
Fast release, water-soluble fertilizers work quickly but don't last long, soon washed away by rain, irrigation, or hand watering within a week or two. Since plants only take up what they need, the runoff overloads our waterways with excess fertilizers every year, contaminating Puget Sound along with caffeine, Vitamin C, Prozac and other medications that harm native salmon and sport fish. Fast fertilizers are fine for hanging baskets but not for living soil. Save high nutrient numbers like 20-20-20 or even 20-50-20 for annuals in containers but don’t use them on mature trees and shrubs, which shouldn’t be fertilized anyway. Overfeeding makes plants vulnerable to pests and diseases, especially trees and shrubs that are already weather stressed. In nature, the only nutrients they need come from a combination of their own fallen leaves and natural compost. To recycle leaf nutrients, shred leaves (lawn mowers!), then use them to mulch around the root zone (drip line) of the tree.
The optimal way to feed both permanent plants and soil is annual mulching with mature, high quality compost. However, fast-growing annuals, vegetables, and fruit trees may need several meals of moderate (5-5-5) organic fertilizers. For lawns, beds, and borders, where lots of plant material is regularly removed, the best options are fertilizers that also feed the soil with probiotic stimulants, mycorrhizae, and beneficial biota. Carefully formulated, naturally-based “slow fertilizers” nourish both plants and healthy soil critters from bacteria to worms. Some excellent brands of organic fertilizers include Dr. Earth, E.B. Stone, and Whitney Farms. Onward, right?
Contact Ann Lovejoy at 413 Madrona Way NE, Bainbridge Island, WA 98110 or visit Ann’s blog at http://www.loghouseplants.com/blogs/greengardening/ and leave a question/comment.
This article originally appeared on Kitsap Sun: Bee-safe, climate friendly and effective fertilizers
