Applying a protective covering on soil surfaces is known as mulching. This is a labour intensive process that leads to multidimensional gains from the point of view of plant care, pest control, soil protection and health, increasing yield and optimizing water use.
Mulching materials can be organic (straw, shredded bark, wood chips) or inorganic (plastic sheets, shredded rubber, crushed glass, volcanic rock, geotextile). Applying mulch is beneficial as it locks in moisture for longer, cushions rainfall and slows water run-off thereby reducing soil erosion, prevents soil crusting or weed growth, and even helps cut off soil pathogens. The added layer above the soil helps regulate soil temperatures from day to night, helps improve aeration and soil structure even.
While carefully done mulching delivers numerous benefits, if done incorrectly the process can end up harming the soil and the plant.
How to choose what to mulch with?
Choose a material based on personal budget and plant requirements. Cool and warm season crops have opposing requirements particularly with respect to soil temperature.
Moreover, most inorganic materials are more expensive than its organic counterparts. It makes sense to use materials locally available – dry leaves, shredded; wood chips; sun-dried grass clippings have many nutrients locked within them which become available to the new plants.
All materials will have associated risks, so do your research before getting started.
Cocoa hulls are fragrant, ornamental and good for the soil but if your farm or garden is home to cats or dogs, this material as that is known to be toxic for them. Piling of hardwood mulch close to the foundation of a structure is likely to attract termites. Plastic sheet mulching is useful though some times challenging to put in place. Over time the plastic starts to break down making removal additionally challenging.
What not to do!
Don’t use too little or too much. 2-4 inches of organic mulch is said to be adequate.
Mulch must not touch the plant at all; circle the stem instead. Decomposing mulch touching the plant can cause rotting.
Ensure there is no volcano or ‘mountain’ piling of mulch around trees. It may look nice but it blocks water and oxygen going to roots. Decomposition of the same also increases the temperature.
Don’t use rocks with mulch even if it may look nice. Rocks tend to heat up faster, which will increase soil and plant temperature significantly.
Lastly, remember to remove some of the older mulch from the bed before you start re-mulching, to maintain an acceptable thickness. And as much as possible, avoid using mulch that has been stored improperly or gone bad. It could do more harm than good.