Chop and Drop: The Fertility Engine Behind Syntropic Systems
Chop and drop is the practice of cutting plants where they grow and leaving the cuttings on the ground as mulch. In syntropic farming it is the main way a planting feeds itself, and it doubles as the pruning that keeps the whole system growing. This post explains where the method comes from, how it works, when and how to do it, and the cautions that apply.
What Chop and Drop Means
A fast-growing support plant is cut back, and its stems, branches and leaves are left in place around the plants that are meant to keep growing. The cuttings protect the soil surface, break down over time and feed soil life. The cut also opens up light for the plants that remain. Nothing is carted away, and nothing needs to be bought in.
Where Chop and Drop Comes From
Ernst Götsch described the method in his 1992 paper on natural succession in agroforestry. Pruning is the main management tool in his systems. Plants that are maturing are cut back, and the cut material is placed on the ground as mulch, which both protects and enriches the soil. Götsch listed several effects of pruning.
It renews maturing plants and speeds up growth across the whole planting.
The cuttings protect and feed the soil.
It changes soil texture and increases earthworm numbers.
It lets more light reach the next generation of plants.
It lets the grower control light, space and leaf area plant by plant.
The paper describes work in the humid tropics. The same idea is used in cooler climates, with species chosen to suit the site. The Syntropic Agriculture page explains the wider method.
The Two Jobs Chop and Drop Does
Feeding the soil
Cuttings left on the surface act as mulch. They shade the soil, hold moisture and slowly break down into organic matter. Over time this builds the layer of organic material that soil life depends on.
Managing growth and light
Götsch observed that plants in vigorous growth encourage their neighbours, while ageing plants slow them. Cutting back plants that have matured, or thinning them, restarts growth across the planting and lets light reach younger plants. In his paper, pruning meant cutting mature plant parts and thinning crowns by 50 percent or more of the branchlets.
What Gets Cut
Chop and drop is used on support plants. In syntropic language, the fast, dense early species that build fertility and shade for later plants are called placenta species. Their job is to prepare the ground, and they are cut back or removed once they have done it. In a temperate planting, support plants can include nitrogen-fixing shrubs and trees, comfrey and other fast-growing pioneer species.
Which plants suit a site varies with climate and soil. Each species should be checked against state weed lists before planting, because some fast-growing support plants are environmental weeds in parts of Australia.
When and How to Cut
Cut when the plant has done its job. Timing follows how the plants are growing, not a fixed date. A support plant is cut when it is maturing or starting to shade the plants beside it.
Use clean, sharp tools. Secateurs, loppers and a pruning saw suit most material. Clean cuts heal better.
Cut large pieces down. Smaller pieces lie flat against the soil and break down faster than long branches.
Lay the material around the plants it should feed. Keep it a hand's width away from tree trunks, because mulch piled against a trunk can cause rot.
Leave it in place. The point of the method is that the material stays on site.
How Much and How Often
There is no fixed schedule. In a young planting the support plants are small, so early cuts give little mulch. Extra mulch or compost may be needed while the support plants grow and while the soil is being rebuilt. As the planting matures, cutting becomes a regular job. Ecologic Solutions' Syntropic Orchard has been managed with about three to four interventions a year. That is the result on one site, and other sites will differ.
Chop and Drop Compared With Other Mulching
Bought mulch or compost. It works at once, but it costs money and has to be carted and spread. It is useful to fill the gap while a young planting is establishing.
Chop and drop. It costs no money and needs no transport, and the material comes from plants that are already improving the site. It only works once enough support plants are growing, so it starts slowly.
Frequently Asked Questions
Is chop and drop the same as composting?
No. Composting breaks material down in a heap before it is used. Chop and drop leaves the cuttings on the soil surface, where they break down in place.
Which plants can be chopped and dropped?
Fast-growing support plants, such as nitrogen-fixing shrubs and trees and comfrey, are common choices. The right species depend on the climate, and each must pass a weed check.
Does chop and drop replace fertiliser?
It can supply much of the organic matter a planting needs. Some sites still need extra inputs, especially while the soil is being rebuilt.
Sources and Further Reading
Götsch, E. (1992). Natural Succession of Species in Agroforestry and in Soil Recovery. Piraí do Norte, Bahia, Brazil.
