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Infiltration Improved by use of Cover Crops
Infiltration is the process of water entering the soil. Infiltration rate is a measure of how fast water enters the soil. Water entering too slowly may lead to ponding on level fields or to erosion from surface runoff on sloping fields. Reducing erosion and runoff also reduce surface runoff of fertilizers and chemicals such as herbicides. Fertilizers and herbicides are agronomic inputs to assist farmers in producing productive and profitable yields. The objective of applying nutrients and herbicides and other chemicals are to benefit the plant. If the inputs runoff, it is a loss to the farmer and the environment.Plants need water and sunshine to produce crop yield. Infiltration is dependent on soil type, soil organic matter and aggregate stability or soil structure. As farmers utilize conservation practices that increase soil organic matter, soil health indicators such as soil structure, aggregate stability, and infiltration will also improve.
Rainfall simulators have become quite common in Tennessee. NRCS uses them to demonstrate how cover crops, no-till, and good grazing practices improve infiltration and reduces erosion. Below is an example of rainfall simulator at Milan No-till Experiment Station on Soil Health Plots.The five trays used were from five treatments left to right, no-till only, NT wheat only, NT cereal rye and crimson clover, NT five-way mix consisting of cereal rye, wheat, crimson clover, daikon radish, and purple top turnip, and NT cereal rye and vetch. Rainfall simulations were run multiple times totaling 3" of water. All trays had good soil structure due to alongterm no-till. As you can see by the back jugs showing infiltration, the 5-way mix infiltrated the best.
In another demonstration, the picture below shows minimum tillage (it is still tillage), no-till, over grazed pasture, conventional tillage tobacco with an excellent cover crop, and good grazing. Note that the good cover crop and the good grazed grass infiltrated and had little runoff compared to other treatments which had high runoff and poor infiltration.