一.Definition of grass layer
The grass layer is the fresh, undecomposed, withered and semi-rotten organic matter formed by the accumulation of dead leaves, stems and roots of lawn grass. The grass layer can be divided into two layers. The upper layer is the fresh grass layer, which is a layer of yellow-brown material in an undecomposed or semi-decomposed state; the lower layer is the decomposed grass layer, which is an organic matter formed by the degradation of fresh grass. The thickness of the grass layer is 6 mm. When the dead grass leaves, stems and roots of lawn grass accumulate at the base, some primary decomposition microorganisms begin to multiply. These microorganisms mainly use relatively easy-to-decompose compounds, proteins, amino acids, sugars, etc. as their own carbon and nitrogen sources of nutrition. After these substances are decomposed, the microorganisms begin to decompose those organic compounds that are more difficult to decompose.If the thatch layer is too thick, it will form an impermeable layer. After rainfall and watering, it is difficult for water to penetrate downwards, thus forming a saturated water layer in the thatch layer. When people step on it, water will come out of the ground, so that groundwater cannot return through the capillary pores. Once the thatch layer dries, the lawn will wilt, and overwatering will form a vicious cycle.
Too thick a thatch layer will affect the elasticity of the lawn, the rebound of the ball falling on the ground, the buffering capacity of soil temperature (the rise and fall of ground temperature), and the permeability of the lawn. In particular, the occurrence of some diseases, such as dollar spot disease, is directly related to the excessive thickness of the thatch layer.
The formation speed of the thatch layer is not only related to the variety of lawn grass, but also directly related to human operations, the types and number of microorganisms in the soil, and the types and frequency of fertilization. For example, if a large amount of nitrogen fertilizer is applied, the lawn will grow faster and the mowing frequency will be more frequent, which will easily form a thatch layer.
The decomposition speed of the thatch layer is related to whether the grass clippings are collected, the number of beneficial microorganisms in the soil, the oxygen content in the soil, and the water content. If the decomposition speed of the thatch layer is relatively fast, then its accumulation speed is relatively slow. In addition, the carbon/nitrogen ratio in materials such as dead branches, leaves, and roots is also very important. Because increasing the carbon/nitrogen ratio can accelerate the number of microorganisms in the soil, so that fresh dead grass can be quickly degraded into mature black substances, the degradation speed of the thatch layer will also be accelerated.
二. The influence of the thatch layer on fertilizers and pesticides
If the thatch layer is thick, it will affect the effect of fertilizers, especially slow-release fertilizers, because slow-release fertilizers are slowly released under the action of microorganisms, and the living conditions of microorganisms in the thatch layer are poor, and the number of microorganisms is limited, so the slow-release fertilizer effect cannot be well exerted. When the thatch layer is thick, some pathogenic bacteria spores exist in it, and the thatch layer has a strong ability to absorb pesticides, so it is difficult for fungicides to penetrate into the deep soil, and it is also difficult to prevent and control pathogens in the soil.
三. Management measures
1. First, choose those lawn grass varieties that are not easy to form a thatch layer, or reseed or interseeded new varieties that are not easy to form a thatch layer on the original varieties.
2. The mowing height should be appropriate, and the grass should not be mowed too low. In addition, the cut grass clippings should be cleared out of the field in time.
3. Excessive application of nitrogen fertilizer will cause the grass to grow too much and too dense, which will accelerate the formation of the thatch layer.
4. Some pesticides affect the activities of microorganisms in the soil. The activities of microorganisms can accelerate the decomposition of the thatch layer, so do not apply pesticides with a long residual effect period.
The decomposition of the thatch layer is completed by microorganisms. If the fungicide is not selected appropriately, the long residual effect period will affect the number of microorganisms in the soil, thereby reducing the decomposition rate of the thatch layer.
四.Artificially accelerate the decomposition of the dead grass layer
It is particularly important to artificially create an environment conducive to the decomposition of the dead grass layer, which can be controlled by measures such as drilling, root cutting, sanding, and applying organic fertilizer.
1. Mechanical method: Use a grass trimmer to trim the grass, a root cutter to trim the grass, and a hole punch to ventilate the grass to make the dead grass clippings and grass roots smaller and finer. At the same time, the fine grass clippings and soil are fully mixed to increase the oxygen content in the soil, which is conducive to the reproduction of microorganisms.
2. Microbial method: At present, scientific research has found a microorganism that can effectively decompose the dead grass layer. Microbial spores can be sprayed in the soil to make the spores proliferate in the soil and accelerate the decomposition of the dead grass layer.
3. Sand covering method You can also cover the dead grass layer with sand to facilitate the reproduction of microorganisms. Especially in the northern courts, a large number of yellow and dead leaves, stems and roots will accumulate under the base of the lawn grass stems in autumn. Burying sand can cover the dead stems and rotten leaves and accelerate the decomposition of grass clippings. When burying sand, use relatively fine sand and adopt a small amount and multiple times to reduce the accumulation rate of the dead grass layer, especially for cold-season lawn grass at the peak of growth.
4. Applying organic fertilizers Applying organic fertilizers can increase the number of microorganisms in the soil and apply some compounds that are conducive to the proliferation of soil microorganisms (such as vitamins, sugars, and proteins). When drilling in spring, the carbon/nitrogen ratio of dead stems and rotten leaves should be analyzed in the laboratory. If it does not meet the requirements, nitrogen fertilizer should be added reasonably, which will increase the content of microorganisms and accelerate the decomposition of the dead grass layer.
Post time: Sep-20-2024