For me, mulching was a learning progression. I live and work in Haiti and experiment with different ideas to see what will work for us in our context. The specific crops and techniques mentioned may or may not work for you, but I’d like to share six basic mulching principles that I have found to be key to promoting soil health.

1. Always keep the soil covered

I was a fan of mulch early on, but I didn’t understand the benefits until I started experimenting with it in very sandy soil. We irrigated some banana plants and compared them with other banana plants mulched without irrigation. Our climate has a three and a half to four-month dry season. If you’re going to grow bananas, you have to irrigate through the dry season. With mulch only  —no irrigation— we could grow bananas all year long. We did that for about five years, never letting the soil go uncovered and mulching with a mix of whatever we had. In most places in the world, there is not enough mulch because organic material is so limited [or there are competing uses for it], leading me to the next principle.

2. Use what you have

It doesn’t matter what type of material it is, use anything you have to mulch! When we first started, we hauled a lot of our mulch in because we used things like sugarcane bagasse, which was available off-site. It was a lot of work to chop it and haul it into the field. I saw the benefits of mulching but was tired of carrying mulch and we still never had enough mulch; it was too labor intensive.

3. Grow your own mulch, just think about it

The first thing I did was just think about growing my own mulch and planning carefully. We started by planting rows of vetiver grass (Chrysopogon zizanioides) everywhere across the land that we took care of (Figure 11). We planted it in rows as field dividers or hedgerows around the outside or to divide up fields. Then we cut and used it as mulch. We planted it in areas in and around the field that would make it convenient to chop and drop it in place. This was so much easier than hauling mulch in!

After a while, we started looking more into green manure cover crops. We tried a bunch of different green manure cover crops, ultimately choosing two; velvet bean (Mucuna pruriens) and jack bean (Canavalia ensiformis). If there is a prolonged off-season, we grow velvet bean, otherwise we grow jack bean. We usually grow the selected cover crop in mixture with sorghum (Sorghum bicolor) and pigeon pea (Cajanus cajan), both of which are drought resistant. We aren’t super organized when planting; we broadcast all three cover crops together because that’s how farmers would do it. I like to have several crops in the ground at once for increased diversity and resilience. And now that is our mulch. With this method, it is growing right where you want it; you just cut and drop it.

4. Grow mulch compatibility and close by 

Grow mulch near the field. If you are intercropping for mulch in your field, make sure your mulch is compatible with your main crop. To test if the mulch crop is compatible, we grow them [the main crop and the mulch crop] side by side in a small section of the field and just observe the crop for signs of competition such as chlorosis, stunting, or delayed maturity. Try growing the crops side by side and see what happens before growing it in the whole field.
If you want farmers to use the grown mulch, it must be in or near the field. You can’t expect them to carry mulch long distances. Mulching can’t be labor intensive or else you will struggle with farmer adoption.

5. Celebrate any adoption

If a crop is both animal food and a mulch, don’t criticize people for feeding it to their animals. The animal is much more valuable than the mulch most times. You have to look at the whole system and understand the bigger cycle the farmer is considering.

We’ve seen a lot of people adapt things so that it fits their context. If they don’t want to spread mulch on their whole field, for example, they just pile it and then the next year they spread it out. I wouldn’t do it that way, but if that works for the farmer, great!

A month before we hold a seminar about mulch, we take the mulch to the site. We plant corn in a small area and mulch half of it as an example. During the seminar, we go out and look at the demonstration and have people evaluate the two plots. Even in the middle of the dry season, we’ve had corn in the mulched area. This activity creates a talking point with the farmers and gives you an opportunity to hear their reactions to the idea of keeping the soil covered.

Resistance to mulching

Our biggest resistance to adopting mulching practices is from crickets. If you mulch a field, crickets may eat your crop in our area. We’ve experienced this, especially with bean crops. And if you’re the only mulched field around, your crops will get decimated. Crickets live and perhaps breed underneath the mulch. If we plant beans or something that crickets like to eat, we won’t mulch them until they are well established, and then the crickets won’t bother them.

6. Soils are alive

When talking with farmers, we don’t start with mulch. We take our time and talk about the fact that soil is alive before we jump into the practice of mulching. Through this educational route, we’ve gotten farmers in an entire area to quit burning. If you can just get people to quit burning, that’s success. Once farmers understand that their soil is alive, then we talk about covering the soil. The key to farmer adoption is loving patiently, walking alongside people, and discovering the “why” with them. It is important to share simple concepts before complex ones and to listen to the way they understand what you say.

We use very basic terms. We talk about soil first because if you tell somebody to mulch without including the “why,” they will not understand the purpose of mulching. If you tell them “Your soil’s alive,” they’ll likely say, “I didn’t hear it say anything”. You have to show them as well.

After talking about soil life, we go dig earthworms in one square foot underneath banana or other healthy trees. We repeat this in the middle of the field to compare the two soils. We go through this and other trainings, mainly through a lot of hands-on activities. After training on soil health and mulching, we go out about every month to conduct follow-up visits with participants. This helps us estimate the adoption rate.

Some mulch options

If you are planting vegetables, you want to use a mulch that will break down faster. If you’re mulching perennials, you want to use a woodier mulch that will break down slower. 

You could use elephant/napier grass (Pennisetum purpureum), but it must be mature, tough and woody, to use as mulch. If you get a lot of rain, it might re-sprout a little, but you just kind of move it around with your foot or a hoe to uproot it and it’ll die. Elephant grass is also a fantastic forage and is helpful in a grazing program. You will see a major yield decline if you plant row crops beside elephant grass, so it is not a good hedge for erosion control. We did tests with elephant grass (Figure 12) with several varieties and we’ve seen negative effects on crop yields up to 25 feet [7.6 m] away from the elephant grass. It competes for nitrogen in the soil and causes yellowing. I’ve seen it negatively affect coffee and pepper yields in the field. We did not see this competition issue with vetiver or Guinea grass.

Sugarcane bagasse breaks down slowly and is usually a waste product. It is like wood mulch but finer and stringy, long and difficult to work with. But once you have it in your garden, it covers the soil for a long time. More decomposed bagasse is somewhat better because the sugars will affect the soil and increase decomposition quickly. It seems like it was causing micronutrient deficiencies, maybe because the microbes in the soil would eat up the nutrients in the soil along with the sugars. This is just a theory of mine. We noticed it specifically in our tomatoes. I would not encourage you to use sugarcane bagasse unless you have a lot.

The one thing we like about jack bean is that it is the most drought resistant for us of any of the cover crops. The seed is so big, there’s really nothing that eats it, unlike other crops. We’d plant in the middle of the dry season and the seed would just lay there in the dry sandy soil until one day you just walk by and see that the jack bean plants sprouted, without rain or irrigation. So, we plant it at any time of the year; we don’t pay attention to rain.

We use gliricidia (Gliricidia sepium) a lot and have never seen it compete with other crops, even fruit trees. We have a dairy project that uses intensive grazing. We’re scattering gliricidia throughout to use as forage, but we’ll go through and cut it to use and lay it down for mulch. We started doing alley cropping trials including different strata of cover crops/living mulch with gliricidia. We’re in our fourth year of an intercropping trial on 1.06 acres (0.43 ha) of land. We have four different strips with cover crops or without cover crops with trees planted about every 25 feet (7.6 m) throughout all cultivated strips. We view these trees as a forage bank for the dry season. We let the trees grow for two years before we harvested them the first time. When we pruned the trees, we cut them so that animals tied to the stumps could not damage the new growth during the growing season. The first pruning of trees, after two years of growth, produced 810 pounds per acre (908 kg/ha) of green leaf matter and 15,000 pounds per acre (16,813 kg/ha) of stems. If a family had this system planted, the stem material would yield about 44 pounds (20 kg) of wood per day . Our staff estimated that this would equal about four days’ worth of cooking fuel. The second pruning of trees, after one year of regrowth, produced 80 pounds per acre (90 kg/ha) of green leaf matter and 10,362 pounds per acre (11,614 kg/ha) of fuelwood.