How Does Rain Splash Erode Bare Garden Soil?

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How does rain splash erode bare garden soil? Rain splash erosion starts where the raindrop meets the soil. When rain falls on bare garden soil, the impact of each drop can move particles off the surface, and that is the start of how rain splash erodes a bed. One research article on crop canopies states the basic process directly: “Soil-particle splashing caused by raindrop impacts on the ground during rainfall is usually evenly distributed if farmlands are not covered with crops.” The rest of this article explains the mechanism, the factors that change its strength, and what the sources do not cover.

Quick answer

• Falling drops strike the ground and detach soil particles. The sources call this “splash erosion”.
• The strength of splash erosion depends on the drops: “The power of splash erosion is related to the size, shape, terminal velocity, and kinetic energy of raindrops.”
• Heavier rain increases it: “An increase in rainfall intensity could significantly enhance the occurrence of splash erosion”.
• Cover between the drops and the soil reduces it: “Crop canopies can effectively reduce rainfall kinetic energy and protect soil surfaces from raindrop impact, thus inhibiting splash erosion.”

What happens at the soil surface

The mechanism begins with impact. A raindrop has energy because it is falling, and that energy is delivered to the soil surface when the drop lands. A review of rainfall simulators describes the requirement in plain terms: “To detach soil aggregates from the soil surface requires energy expenditure.” Soil aggregates are clumps of particles, so the impact has to supply enough energy to break them apart before any particle can leave the surface.

The same review explains where that energy comes from. “In soil erosion research studies, KE can be specified as volume-specific rainfall KE (J m −2 mm −1 ) or time-specific rainfall KE (J m −2 h −1 ) generated by raindrops through their impact on the soil surface.” KE is kinetic energy, and the review states that it is the energy produced by drops hitting the ground.

The first study describes the scale of the process. “Rainfall splash erosion is the initial stage of water erosion and occupies a prominent position in the formation and evolution of erosion.” In other words, splash comes first. The sources do not describe the later movement of those particles in detail.

The impact also has a spatial pattern. The first study notes that splash on open ground is generally even when there are no crops,. The sentence quoted in the introduction makes the same point: splashing is “usually evenly distributed if farmlands are not covered with crops.” Where cover exists, the pattern becomes uneven, which the study links to canopy effects described in the next sections.

Why drop size, shape and speed matter

Not every raindrop has the same effect. The first source lists the drop properties that set the strength of splash: “The power of splash erosion is related to the size, shape, terminal velocity, and kinetic energy of raindrops.” Each property plays a separate role. The sources list these properties together and do not rank them.

The review defines the speed term. “Terminal velocity is defined as the maximum velocity at which a falling raindrop can descend under the influence of gravity and air.” It also explains how the speed is reached. “Raindrops reach their terminal velocity when falling from a certain height, where the sum of the drag force and the force of gravity acting on the raindrop becomes equal.” The review adds that “Fall height in rainfall simulators directly influences the terminal velocity raindrops can achieve during the simulated rainfall event.”

Speed depends on drop size as well. The review reports an early finding by Laws, “revealing that terminal velocity decreases with smaller droplets.” The review also says that the size of drops in a storm can be described with a distribution: “The DSD is defined as the mean number of raindrops within a specific diameter range per unit volume of air.”

The review also notes that the link between drop size and speed can complicate measurement. “While indirect measurement methods simplify raindrop velocity determination by relying on drop size, errors in drop size determination can lead to compounded errors in fall velocity.” For a home gardener, the practical point is limited: the sources describe what drives the energy of impact, but they do not give a rule that turns a particular storm into a particular soil loss.

How rainfall intensity changes the result

Rain intensity is the amount of rain per hour, and it changes splash strongly in the field study. The study states that “An increase in rainfall intensity could significantly enhance the occurrence of splash erosion.” It also gives a measured comparison: “Table 2 also shows that the splash detachment rate under high rainfall intensity (80 mm/h) was two to five times higher than under low rainfall intensity (40 mm/h)”. The rate is the amount of soil detached per unit area per unit time, as defined in the methods.

Intensity affects how many drops hit the soil, and the study connects low intensity with fewer impacts. It describes the low-intensity case this way: “At low rainfall intensity, because of fewer raindrop impacts and longer time to form large raindrops from rain convergence on leaves, large raindrops contributed less to splash erosion, and the regularity became obvious.”

The study also reports that intensity does not act the same way under every cover type. “However, this relationship became complex when rainfall intensity was high (80 mm/h), depending on plant height during different growth periods and the ability of branches and leaves to bear raindrop impact.” That complexity is a reason to avoid treating a single rule as universal. The sources do not report a bare-soil result for that complex case.

The rate also depends on how long the rain lasts and how the test is set up. The study explains that measured amounts are tied to time. “After 30 minutes of rainfall at rainfall intensity of 40 mm/h or 80 mm/h, the splash cups were taken out and oven-dried at 105°C to a constant weight.” The study then reports the detached amount from the weight difference. The study describes its work as “artificial rainfall experiments”, so the figures describe those test conditions, not a garden in general.

How cover changes the result

Cover is the main factor the sources describe for reducing splash on open ground. The field study compared a bare plot with plots under crop canopies. It reports that the mean rate under the four crop canopies “was lower by 67.81% than on bare land” over the whole growth period. That figure averages four crops. The study ranks the crops by their ability to inhibit splash, with “winter wheat>corn>soybeans>millet” in that order.

The closer the cover sits to the soil, the stronger the reduction. The study puts it this way: “Generally, splash erosion amounts decreased with increasing coverage, and the closer the cover is to the ground, the lower are the splash erosion amounts.” The sentence implies that cover close to the ground matters more than cover high above it. The sources do not test mulch by name. For a related guide to surface care, see how to keep garden soil healthy.

Cover is not a complete barrier. The study notes that when cover is not yet full, large drops still reach the soil: “soil detachment caused by large raindrops will still occur” when vegetation cover near the surface is “not yet fully developed or completely canopied”. Early in a season, a bed may have gaps in cover, and the sources suggest those gaps still allow splash.

Tall canopies can also concentrate drops. The study describes how drops gather on leaves and fall as larger drops: “Therefore, large throughfall raindrops formed from raindrops on the leaf margin and apex were an important kinetic energy source for splash erosion occurrence and distribution.”

How researchers measure splash

The field study measured splash with small collection cups. Its method describes the cup and the result: “The splash detachment rate was determined using the method of splash cups.” It then defines the output in terms of area and time: “The splash erosion amount per unit area and per unit time (the splash detachment rate, SDR) was calculated according to the diameter of the splash cup and the rainfall duration.” Each cup was weighed before and after the test, and the difference gave the amount collected.

The review of simulators notes that “Rainfall simulators are designed to simulate rainfall adequately.” It it lists the properties a simulator should match, including “the size spectrum of generated raindrops, their maximum or terminal velocity, the uniformity of the surface distribution of rain, the kinetic energy and the overall intensity of the rain.” If a test rain differs in any of these, the splash numbers will differ from natural rain.

Researchers also use simulated rain for control. The review gives the purpose in one sentence: “The primary purpose of rainfall simulators is to investigate the interaction between rainfall and the land surface, including processes like soil erosion, infiltration, and runoff.” That makes simulators a research tool. The sources treat simulators as a research tool, so a test result is a guide to the process rather than a measurement of one garden.

How we chose these sources

The two sources were chosen because they are research articles on splash detachment and on the rainfall that causes it. Both were opened and checked before any quote was used. The first is a field study of splash under crop canopies, and it gives measured splash rates, including a bare-land comparison. The second is a review of rainfall simulators, and it defines the energy and drop-speed terms used in the first. Neither source is a retail page, and neither is used for a product claim.

What we could not verify

The sources do not describe a home garden bed directly. The field study tested crop plots, and the review covers simulator design. Neither gives a soil-loss figure for a backyard bed, a mulch layer or a raised bed, so this article does not state one. Readers who want soil-structure background can also read how to improve clay soil over time.

What the sources do not say

The sources do not compare splash with sheet flow or rill erosion in a garden, and they do not give a timeline from first splash to visible loss. They also do not test mulch, compost or bark cover by name. The study says the rainfall intensity effect becomes “complex” under taller canopies and does not resolve that complexity for open ground. Where a claim is not in a quote above, this article does not make it.

Frequently asked questions

Does rain splash erode bare soil more than covered soil?

The field study says so for its test plots. Its mean splash rate under the four crop canopies “was lower by 67.81% than on bare land”. The sources report the result for crop canopies, not for garden beds.

Does a light rain cause splash erosion?

The study reports less splash at low intensity. It describes that “large raindrops contributed less to splash erosion” at 40 mm/h. The sources show that lower intensity gives less splash in their test, but they do not give a threshold below which splash stops.

Is splash erosion the same as runoff erosion?

The sources treat splash as the first stage. “Rainfall splash erosion is the initial stage of water erosion and occupies a prominent position in the formation and evolution of erosion.” They do not compare splash with runoff in a garden, so the two are not ranked here.

Can plants or cover reduce splash on a bed?

The sources say cover reduces it. “Crop canopies can effectively reduce rainfall kinetic energy and protect soil surfaces from raindrop impact, thus inhibiting splash erosion.” The study also says the effect depends on the cover type, and it reports that the effect differs by crop.

Why do tall plants sometimes increase splash?

The field study reports that drops falling from higher leaves can carry more energy. It says that “It has strong kinetic energy when big drops falling from higher corn leaves, and increasing splash erosion sharply.” This is a finding for corn in the study, so it does not apply to every plant.

Sources

• Bo Ma. “Effects of Crop Canopies on Rain Splash Detachment.” PMC, National Library of Medicine. https://pmc.ncbi.nlm.nih.gov/articles/PMC4084632/ (opened 2026-10-28, HTTP 200)
• “A review of the characteristics of rainfall simulators in soil erosion research studies.” PMC, National Library of Medicine. https://pmc.ncbi.nlm.nih.gov/articles/PMC10758955/ (opened 2026-10-28, HTTP 200)