HOW TO USE FERTILIZERS SUSTAINABLY
Sometimes our gardens and lawns look a little lackluster, and we default to fertilizer to perk things up. But the overuse of fertilizer can cause significant problems in our lakes, streams, rivers, wetlands, and other groundwater. Too much fertilizer also causes problems for our gardens and lawns, and negatively impacts overall soil health. So, is there a way to use fertilizer sustainably, without harming the environment?
The answer is yes, but it takes a bit more careful planning to ensure it's applied judiciously. The agriculture world follows the 4R's for making sure fertilizer use gives the healthiest crop with the lowest impact on surrounding environments.
The 4 R's of agricultural fertilization are Right Source, Right Rate, Right Time, Right Place. The right source means testing the soil and choosing a fertilizer to balance nutrient levels. The right rate means applying just the right amount so the plants will use up all the fertilizer, and very little or none will leach into the environment. The right time means applying when plants need it most, and when it won't be washed away—usually right before a growth spurt, and not right before a big storm. The right place means applying it exactly where the plants need it, close to the roots, and only right around the plants that need it.
Inorganic fertilizers are often blamed for problems like eutrophication of lakes, rivers, streams, and wetlands. But organic fertilizers can also cause eutrophication when applied indiscriminately. In our gardens and on our lawns, we can use fertilizer sustainably if we're careful about how, what, and when we apply.
CHOOSING THE RIGHT FERTILIZER
The first step is to test your soil so you can choose the right nutrient source. You can pick up soil test kits at our garden center, or you can send off several samples to the county extension office for testing. Ideally, you'll want to test from several different locations in your yard or garden as different areas may be lacking different nutrients.
Once you've gotten your test results back, you can decide what fertilizer to apply based on what's missing. One of the bonuses of organic fertilizers is that many are slow-release. But, sometimes your plants might need a more instant nutrient fix, and inorganic fertilizers, which are usually in liquid form, can give your plants that important short term food they need.
DECIDING HOW MUCH FERTILIZER TO APPLY
Next, you need to determine the right rate, or how much to apply. It's essential not to overfertilize because too much fertilizer of any type can hurt soil health, plant health, and may leach into the water table. Some plants, like tomatoes, can be really heavy feeders and need quite a bit of fertilizer over a season, especially when kept in pots. All fertilizers have a recommended ratio on them, either for mixing with water or for how much to spread per square foot.
For a granular fertilizer, you'll need to measure the space to be fertilized. For water-soluble fertilizer mix it to package directions, and err on the side of caution. A fertilizer mix that's too rich can burn your plant's roots, which makes it even harder for them to absorb nutrients. When in doubt, dilute.
WHEN & WHERE TO APPLY FERTILIZER
Next, you need to pick the right place and time to apply fertilizer. If you're applying fertilizer to the lawn or garden, keep an eye on the weather. The best time to apply lawn fertilizer, which is usually slow-release, is shortly after you've aerated your lawn, and just before a gentle rain. Torrential rain will wash away all your fertilizer and cause problems in nearby waterways. If you're not averse to working in the rain, you can wait until a gentle rain starts and spread while it's raining. Lawn fertilizer should be applied as close to the edges of your lawn as possible without spilling over onto streets or sidewalks where the kernels are likely to get washed away.
For the garden, you'll want to apply slow-release organic fertilizers in the spring. Slow-release fertilizers should be worked into the top 4-5 inches of soil several weeks before you're ready to plant your garden. Any deeper and you risk them leeching out before plants use them up. Left on the surface, they won't provide nutrient dispersal as effectively.
Liquid fertilizer is best applied when the soil is thoroughly damp, but not saturated. In the garden, this means a day or two after rain, with several days of dry weather to follow. For potted plants or raised beds, this means you'll want to water thoroughly a day or two before you apply fertilizer. If the soil is too dry, applying liquid fertilizer will shock and burn the roots of your plants.
The type of fertilizer you're using will affect where you apply it. Fertilizers that have foliar application instructions can be applied on the soil and the leaves of your plants. Do not apply it to the leaves unless the package clearly indicates that foliar application is safe, or you'll burn the leaves. Be conservative when watering with fertilizer. This is not the time to water your pots until water is running out the bottom. That's a waste of good fertilizer, and it's not ideal for it to run out onto the ground below.
IMPROVING SOIL HEALTH
The best way to reduce your reliance on fertilizer, so you can use it sustainably and for best effect on your Indianapolis yard and garden, is to work on improving your soil. This means adding organic matter, like compost, every year to improve the health of your soil. Healthy and balanced soil grows healthier plants that need less fertilizer.
Need some advice on how to safely use fertilizer on your lawn or garden, or improve your soil quality? Give us a call or chat with one of the experts at our garden center. We can help you keep your yard and our water systems as healthy as possible.