Living mulches: its benefits and limitations

Christy BK Sangma

Scientist (Soil Science), ICAR Nagaland


Mulch is simply a protective layer of material that is spread on top of the soil and are used to prevent soil from blowing and being washed away, to reduce evaporation, to increase infiltration, to keep down weeds, to improve soil structure and eventually to increase crop yields. Mulching is one of the simplest and beneficial practices for soil and water conservation. Mulch can either be organic-such as grass clippings, straw, bark chips and similar materials or inorganic such as stones, brick chips and plastic.


Living mulch on the other hand, are type of low-growing ground cover crop that blankets soil like mulch covering the ground throughout the growing season of the main crop (Fig. 1). It can be incorporated with the main crop by inter-seeding or over-seeding, co-seeding or otherwise companion planting.


Fig. 1. Living mulch (clover) with the maize crop
(source: https://phys.org/news/2017-10-clover-corn-combo-benefits-corn-soil)

There are varieties of crops which can be used as living mulch:-
• Hairy/Crown vetch
• Flatpea
• Clover
• Ryegrass etc.


Benefits of living mulch: It has many advantages in crop production. Following are some of the benefits of living mulch:-


1) Erosion Control: The primary benefit of using living mulch is the soil erosion control by intercepting the raindrops and reducing the runoff water. It increases the infiltration into the soil. It also controls the erosion by wind through the thick mantle which protects the soil from detachment and hence prevents the formation soil compaction due to heavy rains. The mulch types which can be effectively utilized under the sloppy land can be vetch, birdsfoot trefoil etc.

2) Increase soil organic matter content: Living mulches build the year round organic matter through incorporation of its residues through shedding and defoliation in the soil (Fig. 2). It becomes concentrated at the soil surface, which greatly improves the soil tilth maintains soil permeability and aeration, overall maintaining the soil health and productivity.


3) Improved soil structure and water holding capacity of soil: Increase in the organic matter in the soil, in turn improves the soil structure and aggregate stability. It also increases the water holding capacity in the soil, or in other words increases the soil moisture retention. Thus saving the need for frequent irrigations and reducing the cost of cultivation.

4) Weed Control: Living mulch offer an effective weed control for the main crop grown. It either suppresses the weed growth or slows down the growth of weeds through its thick covering on the surface. Research has reported that the white clover can control weeds comparable to the commercial herbicides. On the other hand, clover, ryegrass etc. have an allelopathic effect, which suppress the weed growth.

5) Fix atmospheric nitrogen: Leguminous living mulches fix nitrogen from the atmosphere, which can reduce the need for synthetic nitrogen fertilizers. The breakdown of legume plant residues, also releases some of this nitrogen for use by succeeding crops. Examples of nitrogen fixing type of living mulches are hairy vetch, clover etc. This reduction in the application of the synthetic nitrogen fertilizer on the other hand reduces the potential of groundwater nitrate pollution.

Limitation: Living mulches have some limitations also:-

1) It competes for nutrients and water with the main crop which can reduce the yield.
2) Slows down the maturity of the main crop.
3) Some mulch produces the allelopathic effect to the crop.
4) Specialized management practices are required.
5) It lowers the temperature below the mulch.