Filed under: General Info
Professional growers and homeowners are inundated with new products that are promoted to “produce healthy plants.” One such type of product is microbial inoculants that can be added to the soil to “replenish” soil or create a “healthy” soil. These products typically are advertised as providing specific microbes that are somehow missing or inactive.
Soils typically are inhabited by huge numbers of a wide variety of microorganisms, and while there is little doubt that the microbial populations that inhabit the soil and colonize the roots of plants are of critical importance, the introduction of beneficial microbes by inoculating the soil is highly unlikely to lead to any significant benefit. First, it is almost impossible to make changes to the existing microbial populations by just adding an inoculum. Newly introduced microbes cannot compete with the existing populations that inhabit the soil in huge numbers. The introduced microbes are not likely to survive or grow if the nutrients and soil environment are not also modified to the degree that they will have a competitive advantage.
University research performed under controlled laboratory conditions and in field trials has clearly demonstrated that in order for any microbial inoculant to be effective the soil environment must also be controlled. In particular, years of research performed with microbial inoculants introduced to the soil to control plant pathogens has shown that the introduced microbes might grow and survive, but they were not effective unless appropriate sources of organic matter (e.g., composts) were also present. In addition, the quality of the organic amendment had a significant effect not just on the ability of the introduced microbes to grow and survive but also on the activity of the introduced microbes.
Although microbial populations in the soil can benefit plant health, plant growers should be aware that the mere presence of “beneficial” microbes is not enough. Unless the soil environment provides proper nutrients, as may be supplied by composts or other amendments, microbes will not produce the level of activity that is sought. In particular, growers should be skeptical of the simplistic statements made by some organizations such as “healthy soils contain typically 25,000 species of bacteria and 8,000 species of fungi.” This statement implies to the reader that adding species or numbers of microbes will have some benefit. The reality is that the activity of the microbes is most important and long-term changes to microbial activity in the soil will likely require changes to the physical and chemical structure of the soil. The introduction of organic matter through soil amendments is one important way to make long-term changes to the soil environment that will in turn promote changes in microbial populations and microbial activity.
The soil microbial community is amazingly complex and although it is often attractive to make simple statements about the benefits of products, growers and homeowners looking to improve the soil should carefully evaluate claims that promise simple solutions to complex problems.
Filed under: Compost News
Compost, in contrast to common fertilizers, contains nutrients that are part of the organic matter and therefore not readily leached from the soil. Nutrients in compost are made available slowly as the organic matter breaks down in the soil. As they are slowly released, the plant root will absorb the nutrients and risks of nutrients, primarily nitrogen, entering ground water are eliminated. In contrast, commercial fertilizers contain water-soluble forms of nitrogen. Although this nitrogen is readily available to the plants, it is also easily leached into the ground water during heavy rain or irrigation.
Compost test results indicate that Agresoil Compost has about 1% total nitrogen and that most of this is in the organic form. Only about 1% of the total nitrogen is in the water-soluble forms of ammonium-N and nitrate-N. Testing performed on Agresoil Compost also indicates that about 20 % of the compost nutrients will be released in the first year after application thus the amount of plant available nitrogen (the amount that will be made soluble) is about 2.0 lbs of nitrogen per 1,000 square feet of turf when the compost is used at the suggested application rate. Most of this is in the organic form (90%) and will be released slowly as the compost is broken down over the summer.
Soil testing labs typically recommend that 1 lb. Per 1,000 square feet of available nitrogen be applied in the spring and then again in June and late August. This is consistent with the general recommendation for 4 lbs of nitrogen fertilizer per 1,000 square feet of turf.
Thus, topdressing with Agresoil Compost will provide water-soluble nitrogen well within the recommendations issued by labs and is highly unlikely to result in any excess nitrogen that would have the potential to leach to ground water. In order to meet the full recommendation for nitrogen a second top-dressing application should also be considered in the late fall. Compost applied at this time to cool soils will decompose very slowly and nutrients will be released at a rate to optimize plant uptake. In the late fall roots continue to grow and absorb nutrients although top growth is not apparent.
Agresoil Compost will also reduce, if not eliminate, the need to apply lime or other nutrients (P2O5 and K20) as recommended by the soil testing. Compost topdressing will increase the soil organic matter levels and thus also increase the ability of the soil to hold nutrients and water promoting better root penetration in the soil which further reduces risks that nutrients will leach into the ground water.
In conclusion, compost topdressing is an excellent alternative to fertilizer applications and will improve the turf condition with no risk to groundwater resources when performed at the recommended rates.
Filed under: Gardening Ideas
Now that the weather is warm here in New England and we are starting to get into the garden, I am eager to get started using compost again. One of the best ways to use compost at this time, before the danger of frost is gone and before it is safe to plant, is to spread two to three inches over the planting beds. The compost will serve as a mulch and prevent the weeds from getting established. Then when you are ready to plant, all you have to do is mix the the compost into the soil as you dig to put in the plants. This saves time later when you plant and insures that you will have good soil mix for the new plants.
Filed under: Uncategorized
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