CSLB Landscaping (C-27) Trade — All Questions

A soil that drains very quickly, warms fast, and holds little water is MOST likely which texture?

• a.Sandy soil✓
• b.Silt
• c.Peat
• d.Clay

Sandy soils have large particles with large pore spaces, so water drains through rapidly and little is retained. They warm quickly in spring but dry out fast and need more frequent irrigation. Adding organic matter improves their water and nutrient holding capacity.

Most landscape and turf plants grow best in soil with a pH in which range?

• a.About 3.0 to 4.0 (strongly acidic)
• b.About 9.0 to 10.0 (strongly alkaline)
• c.Exactly 8.5 in all landscape soils
• d.About 6.0 to 7.0 (slightly acidic)✓

A slightly acidic to neutral pH of roughly 6.0 to 7.0 keeps most nutrients available for uptake by common landscape plants and turf. Extremely acidic or alkaline soils lock up nutrients even when they are present. Acid-loving plants like azaleas prefer the lower end of this range.

To lower the pH of an alkaline soil, which amendment is commonly used?

• a.Agricultural lime
• b.Elemental sulfur✓
• c.Gypsum for pH change
• d.Wood ash

Elemental sulfur is oxidized by soil bacteria into sulfuric acid, gradually lowering soil pH over weeks to months. Lime and wood ash raise pH, and gypsum changes soil structure and adds calcium without significantly changing pH. Sulfur is the standard choice to acidify alkaline soils.

In a fertilizer labeled 16-6-8, the three numbers represent the percentage of which nutrients in order?

• a.Phosphorus, nitrogen, potassium
• b.Potassium, phosphorus, nitrogen
• c.Nitrogen, phosphorus, potassium✓
• d.Nitrogen, potassium, phosphorus

The three-number N-P-K label always lists nitrogen first, phosphorus (as P2O5) second, and potassium (as K2O) third. So 16-6-8 is 16 percent nitrogen, 6 percent phosphorus, and 8 percent potassium by weight. Nitrogen drives leafy green growth, phosphorus supports roots and flowers, and potassium aids overall vigor.

A 50-pound bag of 20-0-10 fertilizer contains how many pounds of actual nitrogen?

• a.1 pound
• b.20 pounds
• c.5 pounds
• d.10 pounds✓

Actual nitrogen equals the bag weight times the nitrogen percentage, so 50 pounds times 0.20 equals 10 pounds of nitrogen. Landscapers use this calculation to apply the correct pounds of nitrogen per 1,000 square feet. Knowing actual nutrient content prevents over- or under-application.

Applying a 3-inch layer of organic mulch around plants primarily provides what benefits?

• a.It increases soil compaction around the roots
• b.It eliminates all irrigation needs
• c.It conserves moisture and suppresses weeds✓
• d.It raises soil pH sharply within days

A layer of organic mulch reduces evaporation, keeps soil temperatures more stable, and blocks light that weed seeds need to germinate. As it decomposes it also adds organic matter to the soil. Mulch is one of the most cost-effective water-saving practices in landscaping.

When planting a container-grown shrub, the top of the root ball should be placed at what level relative to the surrounding soil?

• a.6 inches below grade
• b.Buried under 4 inches of soil over the crown
• c.At or slightly above the surrounding grade✓
• d.12 inches below grade

The top of the root ball should sit at or slightly above finished grade so the crown does not sit in water and settle too deeply. Planting too deep suffocates roots and can rot the crown or trunk. Slightly high planting allows for minor settling while keeping the crown dry.

Gypsum is added to certain clay soils primarily to accomplish what?

• a.It lowers the soil pH significantly
• b.It kills weed seeds already in the bed
• c.It displaces sodium and improves structure✓
• d.It adds a large amount of nitrogen

Gypsum, calcium sulfate, supplies calcium that replaces sodium in sodic clay soils, improving aggregation and water penetration. It changes soil structure and drainage without appreciably altering pH. It is not a fertilizer and does not add nitrogen.

A newly planted tree needs staking. What is the correct staking practice?

• a.Wrap wire tightly around the bark
• b.Allow movement and remove stakes in a year✓
• c.Tie the trunk rigidly for at least five years
• d.Drive one stake straight through the root ball

Stakes should support the tree while allowing slight trunk movement, which encourages a stronger trunk and root system. Ties should be loose and use a broad, soft material, and stakes are typically removed after about one growing season. Rigid staking and bare wire damage the tree and create a weak, dependent trunk.

Which practice BEST improves drainage in a heavy clay planting bed?

• a.Compact the soil before planting
• b.Line the bottom of the bed with plastic sheeting
• c.Add fine sand only in small amounts
• d.Incorporate organic matter such as compost and improve grading✓

Blending compost and other organic matter into clay improves aggregation, creating larger pore spaces that let water move through. Combined with grading that directs excess water away, this relieves waterlogging. A small amount of sand can actually make clay worse by forming a concrete-like mix, and plastic traps water.

Proper plant spacing at installation should be based on what?

• a.The size of the nursery container only
• b.Fitting as many plants as possible
• c.The mature size and spread of the plant✓
• d.The current size of the plant

Plants should be spaced according to their expected mature width so they fill in without overcrowding. Spacing based on current small size leads to crowding, poor air circulation, and disease as plants grow. Good spacing reduces long-term maintenance and pruning.

A soil amendment high in nitrogen but low in decomposition, like fresh wood chips tilled into soil, can cause what short-term problem?

• a.A large and rapid rise in soil pH
• b.Temporary nitrogen deficiency, or drawdown✓
• c.Excess nitrogen that burns the plants
• d.Immediate salt toxicity in the root zone

When high-carbon materials like fresh wood chips are mixed into soil, microbes decomposing them consume available nitrogen, temporarily starving plants of it. This nitrogen drawdown causes yellowing until decomposition slows. Using wood chips as surface mulch instead of tilling them in avoids the problem.

Cool-season turfgrasses such as tall fescue grow most actively in which conditions?

• a.Deep winter freezes only
• b.Cooler spring and fall temperatures✓
• c.Complete shade year round
• d.The hottest summer weeks

Cool-season grasses like tall fescue peak in growth during the cooler temperatures of spring and fall and slow down in summer heat. Warm-season grasses such as Bermuda are the opposite, thriving in summer. Choosing the right type for the climate reduces water and maintenance needs.

When establishing turf from seed, keeping the seedbed consistently moist is important because what?

• a.Water is needed only after sprouts appear
• b.Seeds germinate better when completely dry
• c.Germinating seeds and shallow roots die quickly✓
• d.Moisture prevents any weed growth at all

Germinating seeds and their tiny first roots sit near the surface and die rapidly if the seedbed dries out. Light, frequent watering keeps the top layer moist until seedlings establish deeper roots. Once established, watering shifts to deeper and less frequent cycles.

Rough grading followed by finish grading before planting is done primarily to accomplish what?

• a.To create low spots that hold water
• b.To increase soil compaction before planting
• c.To set surface drainage and a smooth planting bed✓
• d.To remove all topsoil from the site

Grading shapes the soil surface so water drains away from structures and toward intended outlets, and finish grading creates a smooth, even bed for planting or turf. Poor grading causes ponding, erosion, and drainage complaints. Positive slope away from buildings is a core goal.

Compost is added to soil primarily to do what?

• a.To improve structure and add organic matter✓
• b.To compact the soil around new plants
• c.To serve as the only nutrient source
• d.To raise pH to strongly alkaline levels

Compost improves soil structure, increases water and nutrient holding capacity, and feeds beneficial soil microorganisms. While it adds some nutrients, its main value is as an organic amendment that improves overall soil health. It benefits both sandy and clay soils.

Which plant selection strategy BEST supports water-efficient landscaping in California?

• a.Drought-tolerant plants grouped by water need✓
• b.Mixing high- and low-water plants on one valve
• c.Select plants at random from the nursery
• d.Plant only high-water tropical species

Selecting drought-tolerant, climate-appropriate plants and grouping them by similar water needs, called hydrozoning, lets each irrigation zone be scheduled efficiently. Mixing high- and low-water plants on one valve forces overwatering of the low-water plants. Hydrozoning is a core MWELO efficiency practice.

A soil test reports very low phosphorus. Which fertilizer analysis would BEST correct it?

• a.21-0-0
• b.46-0-0
• c.0-0-60
• d.0-45-0✓

The middle number of the N-P-K label is phosphorus, so 0-45-0 supplies a high level of phosphorus and nothing else. 21-0-0 and 46-0-0 supply only nitrogen, and 0-0-60 supplies only potassium. Matching the deficient nutrient to the fertilizer analysis avoids waste.

Balled-and-burlapped (B&B) trees should have synthetic burlap and wire baskets handled how at planting?

• a.Removed only after two full growing seasons
• b.Left fully intact around the entire root ball
• c.Never touched once the tree is set
• d.Loosened and folded down, synthetics removed✓

Natural burlap decomposes, but synthetic burlap and twine do not and can girdle roots, so they should be removed or at least peeled back from the top of the root ball. Wire baskets are cut and folded down after the tree is set. This lets roots grow outward into the surrounding soil.

Slow-release (controlled-release) fertilizers are advantageous because they do what?

• a.They release all their nutrients in one day
• b.They contain no nitrogen or potassium
• c.They feed gradually, cutting burn and leaching✓
• d.They only work below freezing temperatures

Controlled-release fertilizers meter nutrients out over weeks or months, lowering the risk of fertilizer burn and reducing nutrient leaching into groundwater. This gives steadier plant growth and fewer applications. They are especially useful for sandy soils where quick-release nutrients leach fast.

The planting hole for a balled tree should generally be dug how wide relative to the root ball?

• a.Ten times the width and twice as deep
• b.The same width but twice as deep as the ball
• c.Two to three times the width of the ball✓
• d.Half the width of the root ball

A hole two to three times as wide as the root ball loosens surrounding soil so new roots spread outward easily, while keeping depth equal to the ball prevents settling and deep planting. Digging deeper than the ball causes the tree to sink and the crown to sit too low. Wide and shallow is the standard rule.

Salt buildup in soil from irrigation water or fertilizer is BEST managed by what practice?

• a.Deep irrigation to leach salts downward✓
• b.Adding more fertilizer to the planting bed
• c.Compacting the soil surface very firmly
• d.Reducing all watering to zero for a month

Applying a deep, thorough irrigation, called leaching, dissolves accumulated salts and carries them downward below the root zone where they no longer harm plants. This requires soil with adequate drainage. Adding more fertilizer would worsen the salt problem.

A soil report lists 45 percent sand, 35 percent silt, and 20 percent clay. What texture class is that, and what does it mean for irrigation?

• a.Clay loam, which requires frequent shallow irrigation cycles
• b.Silt loam, which holds the most water of any texture class
• c.Loam, which holds moderate moisture and drains at a moderate rate✓
• d.Sandy clay, which drains slowly and needs long soak periods

That mix falls in the loam class, the balanced texture that both retains usable moisture and drains at a workable rate. Sandy clay would need far more clay. Silt loam would need silt to dominate, and even then peats and organic soils hold more water. Clay loam is heavier than these percentages describe and is not watered by frequent shallow cycles.

Two beds are irrigated identically, one in sand and one in clay loam. Why does the sand bed need water more often?

• a.Sand transmits more water upward to the leaf canopy
• b.Sand loses more water to evaporation from the surface
• c.Sand has a higher permanent wilting point than clay loam
• d.Sand holds less available water per foot of soil depth✓

Large pores drain quickly and hold little water against gravity, so sand stores far less plant-available water per foot of depth and empties sooner. Surface evaporation is similar for both when mulched. Clay actually has the higher wilting point because it holds water too tightly to release. Soils do not transmit water to the canopy; roots and the plant do.

A percolation test in a proposed tree pit shows water standing in the hole 24 hours after filling. What does the installer conclude?

• a.The pit should be dug wider so more surface area is exposed
• b.The pit needs additional organic amendment mixed into the backfill
• c.Drainage is inadequate and the planting detail must be changed✓
• d.The soil is within the normal range for a clay site

Water standing a full day means the pit will hold the root ball in saturated soil, so the detail must change, whether by mounding, subdrainage, or moving the tree. Amending backfill in a poorly draining hole creates a bathtub that fills faster. Widening the hole does not give the water anywhere to go. A full day of standing water is a failure, not a normal clay result.

A landscape is failing in a heavy clay pad that was compacted by grading equipment. Which corrective measure addresses the root cause?

• a.Increasing irrigation frequency to keep the surface moist
• b.Ripping the compacted layer and incorporating organic matter✓
• c.Top-dressing with two inches of sand across the pad
• d.Applying a complete fertilizer at twice the label rate

Compaction destroys pore space, so roots and water cannot move, and breaking that layer and blending in organic matter restores structure. Extra fertilizer does not create pore space and can burn stressed roots. More frequent watering keeps a compacted soil saturated. A thin sand layer over clay creates a perched water table rather than drainage.

A soil test returns a pH of 8.1 on a site where azaleas are specified. What is the most practical response?

• a.Apply agricultural lime to buffer the soil before planting
• b.Plant as drawn and correct the pH with monthly acid rinses
• c.Revise the plant list toward species tolerant of alkaline soil✓
• d.Increase the phosphorus rate to offset the high pH

Sustained pH change on an alkaline California soil is slow, expensive, and prone to rebound, so matching the plants to the site is the durable answer. Lime raises pH and would make the problem worse. Extra phosphorus does not change pH and can tie up other nutrients. Monthly acid applications are a maintenance burden that rarely holds.

Which amendment is used to lower the pH of an alkaline landscape soil over time?

• a.Wood ash spread evenly and watered in
• b.Elemental sulfur, which soil bacteria convert to acid✓
• c.Dolomitic limestone worked into the top six inches
• d.Calcium carbonate blended with the backfill

Soil bacteria oxidize elemental sulfur into sulfuric acid, which is the standard way to move pH downward. Dolomitic limestone and calcium carbonate are liming materials that raise pH. Wood ash is strongly alkaline and raises pH as well, so three of these four choices move the soil in the wrong direction.

Newly emerging leaves on a citrus tree are yellow between green veins while older leaves stay dark green. What does this pattern suggest?

• a.Nitrogen deficiency, which appears first on new growth
• b.Phosphorus deficiency from cold soil temperatures
• c.Iron deficiency, common where soil pH is high✓
• d.Potassium deficiency caused by excess irrigation

Iron is immobile in the plant, so a shortage shows on the newest leaves as interveinal chlorosis, and it is common on alkaline California soils where iron is present but unavailable. Nitrogen is mobile and yellows the oldest leaves first and uniformly. Potassium shortage shows as marginal scorch on older leaves. Phosphorus shortage typically shows as dull purpling.

A 50-pound bag is labeled 15-5-10. How much actual nitrogen does the bag contain?

• a.1.5 pounds
• b.3.0 pounds
• c.7.5 pounds✓
• d.5.0 pounds

The first number is percent nitrogen by weight, so 15 percent of 50 pounds is 7.5 pounds. The 1.5-pound figure would come from a 3 percent product. Three pounds would come from a 6 percent product. Five pounds is the phosphate content of this bag expressed the same way, which is a common mix-up.

A specification calls for one pound of actual nitrogen per 1,000 square feet using a 20-0-10 fertilizer. How much product is applied per 1,000 square feet?

• a.10 pounds
• b.20 pounds
• c.2 pounds
• d.5 pounds✓

Dividing the pound of nitrogen wanted by the decimal fraction of nitrogen in the product gives 1 divided by 0.20, or 5 pounds of product. Ten pounds would deliver two pounds of nitrogen. Twenty pounds would deliver four pounds and risk burning. Two pounds delivers only four tenths of a pound and falls short of the specification.

An owner asks why the crew uses a controlled-release fertilizer on a slope above a creek instead of a soluble product.

• a.It contains more total nutrient per bag and covers more ground
• b.It changes soil pH less than soluble products do
• c.It releases gradually, lowering burn risk and leaching✓
• d.It costs less per pound of nitrogen than soluble fertilizer

A coated or slow-release product meters nutrient out over weeks, so less is available to wash off in a storm and less is present at any moment to burn roots, which matters directly above a waterway. Analysis per bag is usually lower rather than higher. Both types can affect pH depending on nitrogen source, and slow-release costs more per pound of nitrogen.

Fresh wood chips are tilled into a planting bed and the plants yellow within weeks. What happened?

• a.The chips held water and drowned the shallow feeder roots
• b.The chips raised soil pH beyond the range the plants tolerate
• c.The chips released natural herbicides that damaged the roots
• d.Microbes decomposing the chips tied up available soil nitrogen✓

High-carbon material incorporated into soil feeds a microbial bloom that immobilizes nitrogen while it decomposes, and the plants go hungry until the process finishes. Wood chips do not shift pH sharply. Allelopathic effects are limited to a few species and not the general case. Chips tilled in improve aeration rather than causing saturation.

How should the same wood chips be used so that nitrogen tie-up is not a problem?

• a.Left on the surface as mulch rather than incorporated✓
• b.Composted for two weeks and then tilled in at six inches
• c.Applied with a high-phosphorus starter fertilizer at planting
• d.Blended at no more than ten percent by volume into backfill

Tie-up happens where carbon and soil are mixed, so leaving chips on top confines the effect to a thin surface layer while the mulch still suppresses weeds and holds moisture. Two weeks is not enough composting. Even ten percent by volume still incorporates raw carbon. Phosphorus does not substitute for the nitrogen the microbes take.

What does MWELO require of a project regarding soil before the planting plan is finalized?

• a.A geotechnical report establishing the bearing capacity of the subgrade
• b.A record of the last three crops or land uses on the parcel
• c.A soil management report with testing and amendment recommendations✓
• d.A certified laboratory analysis of the irrigation water source

MWELO requires a soil management report so that amendment and mulching decisions are based on actual soil chemistry and texture rather than habit. Water quality analysis is useful but is not the required report. Bearing capacity belongs to structural design. Prior cropping history is not part of the ordinance.CA MWELO (Title 23)

MWELO sets a minimum mulch depth on exposed soil in planting areas. Which statement matches the requirement?

• a.Two inches, applied everywhere including turf areas
• b.Four inches, with the layer piled against trunks to hold moisture
• c.At least three inches, with turf and creeping groundcover excepted✓
• d.One inch, refreshed each time the landscape is fertilized

The ordinance calls for a minimum three-inch layer on exposed soil in planting areas and recognizes that turf, rooting groundcover, and direct-seeded areas cannot be mulched that way. Two inches falls short of the minimum. Four inches piled against trunks invites collar rot. One inch neither suppresses weeds nor conserves moisture.CA MWELO (Title 23)

Why must organic mulch be pulled back from the trunk of a newly planted tree?

• a.Mulch against the trunk prevents the root flare from taking up nitrogen
• b.Constant moisture against the bark encourages crown and collar rot✓
• c.Mulch against the trunk raises the soil pH in the root ball
• d.Mulch against the trunk attracts beneficial insects away from the canopy

Bark is not built to stay wet, and mulch heaped against it holds moisture that leads to collar rot and encourages rodents and adventitious roots. Insects are not the driving issue. The flare does not take up nitrogen. Mulch has little effect on pH within the root ball, and none of that would justify burying the trunk.

A five-gallon shrub comes out of the can with roots circling tightly around the outside of the root ball. What should the installer do?

• a.Plant it as is so the intact root ball is not disturbed
• b.Prune the top by a third to balance the restricted roots
• c.Score or tease the circling roots apart before backfilling✓
• d.Set it two inches deeper so the circling roots are covered

Circling roots continue to circle and eventually girdle the plant, so cutting or teasing them outward at planting is required. Planting as is preserves the defect. Pruning the top does not correct roots. Planting deeper buries the root crown, adds a second problem, and still leaves the circling roots in place.

What is the correct relationship between the root flare of a new tree and the surrounding finish grade?

• a.The flare is covered by four inches of amended backfill
• b.The flare is set level with the bottom of the watering basin
• c.The flare sits two inches below finish grade
• d.The flare sits at or slightly above finish grade✓

Planting with the flare at or slightly above grade keeps the trunk base dry and is the single most common difference between trees that establish and trees that decline. Setting the flare below grade or burying it under backfill traps moisture against the bark. A basin bottom sits below grade, so matching it would bury the flare as well.

Current practice for backfilling a tree pit in average native soil is which of the following?

• a.Backfill with imported topsoil to the full depth of the pit
• b.Backfill with native soil below and pure compost in the top foot
• c.Backfill with a fifty-fifty blend of native soil and nursery compost
• d.Backfill with the native soil that came out of the hole✓

Backfilling with native soil encourages roots to move out into the surrounding profile instead of staying in a rich pocket, and it avoids the texture interface that stalls water movement. Heavy compost blends, imported topsoil, and a compost cap all create that interface and can leave the tree rooted only inside the hole.

How wide should a planting hole be relative to the root ball, and why?

• a.Two to three times as wide, so loosened soil eases root spread✓
• b.Half again as wide, so amendment can be layered around the ball
• c.The same width, so the ball is held firmly on all sides
• d.Four times as wide, so a full drainage envelope can be created

A wide shallow hole gives new roots loosened soil to grow into laterally, which is where feeder roots actually go, and two to three times the ball width is the accepted range. A tight hole leaves compacted walls. Layering amendment around the ball creates a texture interface. Four times the width is unnecessary excavation with no added benefit.

A balled-and-burlapped tree arrives in a wire basket with synthetic burlap. What is the correct handling at planting?

• a.Leave the wrapping intact, since both materials break down in soil
• b.Set the tree, then cut away the upper basket and synthetic burlap✓
• c.Cut the burlap only at the top and leave the basket untouched
• d.Remove the basket entirely before the tree is set in the hole

Handling by the ball keeps it intact, so the tree is set first and the upper basket and all synthetic burlap are then cut away, since synthetic burlap never rots and wire can girdle roots. Leaving the wrapping intact assumes a decomposition that does not happen. Removing the basket before setting risks breaking the ball. Cutting burlap alone leaves the wire in place.

Two stakes are installed on a new tree. What describes correct staking?

• a.Ties pulled tight so the trunk cannot flex in any direction
• b.Ties placed just below the lowest branch and left for three seasons
• c.Stakes driven through the root ball for maximum holding power
• d.Ties placed low, allowing some trunk movement, removed within a year✓

Trunk movement builds taper and strength, so ties go low, stay loose, and come off once the tree anchors, usually inside a year. Tying high and leaving stakes for years produces a weak whippy trunk. Stakes driven through the ball damage roots. Rigid ties prevent the very movement that develops trunk strength.

In most of California, which season generally gives the best establishment for woody landscape plants?

• a.Late winter, when plants are fully dormant and shipping is easiest
• b.Midsummer, when nursery stock is fully hardened off
• c.Fall, when soil is still warm and winter rain follows✓
• d.Late spring, when soil has warmed and growth is rapid

Fall planting lets roots grow into warm soil while cool weather and coming rain reduce demand on the canopy, so plants enter their first summer established. Late spring gives only weeks before heat arrives. Midsummer planting stresses new roots hardest. Deep winter works for bare root stock but leaves cold soil and slow root activity for most container plants.

A shrub shows wilted foliage, and the soil around it is wet and smells sour. What is the most likely diagnosis?

• a.Transplant shock from root disturbance at installation
• b.Root rot from saturated soil starving roots of oxygen✓
• c.Drought stress that will resolve after one deep watering
• d.Salt burn from fertilizer applied at too high a rate

Roots need oxygen, and in saturated soil they suffocate and rot, which produces wilting that looks like drought while the soil is wet and smells anaerobic. Adding water makes it worse rather than better. Salt burn shows as marginal leaf scorch in dry soil. Transplant shock does not produce sour saturated soil.

A soil analysis reports a high electrical conductivity and a history of irrigation with hard well water. What management practice is indicated?

• a.Till the top foot to blend the salts through the profile
• b.Apply extra water periodically to leach salts downward✓
• c.Increase nitrogen so plants outgrow the salt injury
• d.Reduce irrigation volume so fewer salts arrive in the soil

Salts accumulate as water evaporates, and the only way to remove them is to move them downward with water applied beyond plant demand, provided the soil drains. Reducing irrigation concentrates salts further. Nitrogen fertilizer is itself a salt and adds to the load. Tilling redistributes salts without removing any of them.

Gypsum is recommended for a soil that has high sodium and poor structure. How does it work?

• a.It adds organic matter that binds soil particles together
• b.It increases the clay fraction so the soil holds more water
• c.It lowers soil pH directly by releasing free acid
• d.Calcium displaces sodium on clay particles so they can aggregate✓

Gypsum supplies calcium that exchanges with sodium on clay surfaces, letting particles flocculate into crumbs so water and air can move; the displaced sodium then leaches. It is neutral and does not lower pH the way sulfur does. It contains no organic matter and does not change the texture class of the soil.

A crew applies gypsum to a compacted clay pad that has normal sodium levels. What result should be expected?

• a.Slow improvement, because gypsum must first lower soil pH
• b.Rapid improvement, because gypsum increases infiltration on any soil
• c.Little improvement, because the problem is compaction not sodium✓
• d.Marked improvement, because gypsum loosens all clay soils

Gypsum corrects sodium-affected soils, and where sodium is not elevated it does very little, so the compacted pad still needs mechanical loosening and organic matter. It is not a general clay loosener, it does not raise infiltration on non-sodic soils, and it is not a pH-lowering material.

MWELO gives a compost incorporation rate for landscape areas where the soil report does not specify otherwise. Which statement reflects it?

• a.Six cubic yards per 1,000 square feet incorporated to a twelve-inch depth
• b.Two cubic yards per 1,000 square feet spread and left on the surface
• c.One cubic yard per 1,000 square feet worked into the top three inches
• d.Four cubic yards per 1,000 square feet incorporated to a six-inch depth✓

The ordinance default is four cubic yards of compost per 1,000 square feet of permeable area worked to a depth of six inches. One cubic yard at three inches is too little to change soil behavior. Compost left on the surface is mulch rather than incorporation. Six cubic yards to a foot exceeds what the ordinance requires and is rarely practical.CA MWELO (Title 23)

What is the primary long-term benefit of adding compost to a landscape soil?

• a.It builds structure, improving both water holding and aeration✓
• b.It supplies a high concentration of immediately available nitrogen
• c.It raises soil pH into the optimum range for most landscape plants
• d.It permanently changes the soil texture class toward loam

Compost feeds soil biology and builds aggregates, which improves water retention in sand and drainage in clay at the same time. Its nutrient release is slow and modest rather than concentrated. Texture is set by particle size and does not change with amendment. Effects on pH depend on the feedstock and are not a reliable benefit.