Landscaping (C-27) · Lesson 2 of 7

Soil Prep Takeoff: Compost and Mulch Quantities (MWELO)

"Soil Prep Takeoff: Compost and Mulch Quantities (MWELO)" is lesson 2 of 7 in the Landscaping (C-27) Learning Hub. It opens with "Soil Preparation Is Part of the Water Budget" and works through 5 short steps, then a worked example you can check yourself against.

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Steps in this lesson

  1. Soil Preparation Is Part of the Water Budget
  2. Compost Rate: 4 Cubic Yards per 1,000 Square Feet
  3. Mulch Rule: 3 Inches on Exposed Bed Soil
  4. Do the Takeoff: Area, Then Depth, Then Yards
  5. Why It Matters on Irrigation

The worked example in the course applies this lesson to a realistic job in 6 steps, from "Beds that need mulch" through "Round up to a whole delivered yard".

What you'll be able to do

  • Explain the main idea of "Soil Prep Takeoff: Compost and Mulch Quantities (MWELO)" in plain language you can use on the exam.
  • Apply this step with confidence: "Mulch Rule: 3 Inches on Exposed Bed Soil".
  • Apply this step with confidence: "Do the Takeoff: Area, Then Depth, Then Yards".
  • Apply this step with confidence: "Why It Matters on Irrigation".
  • Test yourself on the worked example and the quick-check quiz inside the classroom.
Compost and Mulch: Two MWELO QuantitiesSOIL SECTION (side view)mulchcompost mixedinto top 6 in.native soil3 in. mulch min.6 in. depth:4 cu yd compostper 1,000 sq ftMWELO Sec. 492.6(a)(3)(C)-(D)COMPOST4 cu yd per 1,000 sq ft of permeable area5,000 / 1,000 x 4 = 20 cu ydMULCH (3 in. on exposed bed soil)5,000 - 1,200 turf - 300 groundcover = 3,5005% habitat: 0.05 x 5,000 = 250 sq ft unmulched3,500 - 250 = 3,250 sq ft to mulch3,250 x 3/12 ft = 812.5 cu ft812.5 / 27 = 30.09 cu ydRound up: order 31 cu ydNo habitat strip: 3,500 x 0.25 / 27 = 32.4 cu ydso 33 cu ydSoil with more than 6% organic matter in the top 6 in. is exempt from compost and tilling.Compacted soil must be made friable before planting (Sec. 492.6(a)(3)(A), (C)).ORDER: 20 cu yd compost + 31 cu yd mulchSource: MWELO (23 CCR Div. 2, Ch. 2.7) Sec. 492.5, 492.6(a)(3) and (b)(6)-(7). Totals rounded up for delivery.CC
The diagram for this lesson, exactly as it appears in the Learning Hub.

The first steps of this lesson

Step 1: Soil Preparation Is Part of the Water Budget

MWELO makes soil preparation a required part of the landscape design plan, not an optional extra. Before any planting, compacted soil must be transformed to a friable condition (on engineered slopes, only the amended planting holes need to meet this), and amendments must follow the soil report and suit the plants selected (MWELO Sec. 492.6(a)(3)(A)-(B)). The soil report itself tests texture, infiltration rate, pH, total soluble salts, sodium, percent organic matter and gives recommendations (Sec. 492.5(a)(1)(B)).

Step 2: Compost Rate: 4 Cubic Yards per 1,000 Square Feet

The printed rule is: compost at a minimum rate of four cubic yards per 1,000 square feet of permeable area, incorporated to a depth of six inches into the soil (MWELO Sec. 492.6(a)(3)(C)). That is a rate per area, so the quantity is (permeable area / 1,000) x 4. Soils with more than 6 percent organic matter in the top 6 inches are exempt from adding compost and tilling (same section). Compost is incorporated, so it is mixed into the top 6 inches, not spread on top.

The remaining 3 steps, the worked example and the quiz are in the course. This is a preview. The full lesson, with the step-by-step explanations, a worked example and a quick-check quiz, is inside the classroom.

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