Sorry for the delay in getting the series going! Let’s dive in.
There are four principles or ‘non-negotiables’ of conservation agriculture (CA):
1. Minimal soil disturbance (no till – minimum tillage)
2. Residue retention / crop cover
3. Crop rotation
Doing 1-3 equates to conservation farming and doing 1-4 to conservation agriculture. Other pillars to practicing CA properly and to maximize on its benefits are precision and timeliness. Precision in terms of distance between and within rows, land leveling, plant population, herbicide and fertilizer application.
For example, there is an optimal distance between each plant. If rows are too close together, the soil will be overworked and plants will be crowded, competing for nutrients from the soil and light from the sun, resulting in weak plants. Timing is meant in terms of when the farmer plants and when herbicides, pesticides and fertilizer are applied. For example, if a farmer applies fertilizer too early or too late, the plant will not be able to optimize nutrient absorption, thus affecting its growth. To be imprecise or off-schedule means that entire crop will be inefficient.
The aim is to maintain soil structure. Studies have been done that show soil is interconnected and has vast web of communication (for more on this, see links below). When a farmer takes a till to his/her land, this structure is destroyed. The soil also looses moisture and releases CO2 into the atmosphere. Furthermore, top soil is what keeps on getting churned, exposing nutrients to the sun and wind, which leads to infertility much sooner. The layer beneath the reach of the tilling machine becomes compacted year after year, causing water runoff as it has a harder time seeping downwards. These effects combined, make it difficult for a plant to set down strong and healthy roots, which in turn affect the productivity of the plant.
Minimum tillage, as its name suggests, minimizes these negative effects. Two methods that keep soil disturbance low, were taught to us. One that involves manual labor and creating basins. Second, is a mechanized method using a ripper. Converting from conventional plowing / tillage to minimum tillage, would also allow ravaged land time to heal. It needs to be explained to farmers that to really see the benefits of minimum tillage, a few seasons are needed.
Residue retention / crop cover
The first rule is no burning of crop residue (e.g. maize stalks). In fact, no burning of any kind. This too disturbs soil structure. In CA, the crop residue is what provides soil cover and as it disintegrates, replenishes the soil with nutrients. Josphat describes it in this way to farmers he trains by asking where a plant get what it needs to grow. Once they tell him from the soil, he points out that the plant is taking it from the soil and must thus return it so the next plant can grow.
Crop cover means actual live plants that return nutrients to the soil during the off season and at the same time provide shade for the soil. Shade for the soil is important to reduce moisture evaporation. Crop cover examples that work in Ghana are macuna and pigeon pea. In northern Ghana, not much survives because of the harmattan and hot season where, right now, no rain falls from October through February. Sporadic rains come throughout March – May with the real rains only arriving in June. Even then, its pattern is erratic.
In 2016, in the West Mamprusi District we had eight to ten heavy and hard rains, where every two weeks we would have some grey days of non-stop drizzle. So, whatever moisture that can be retained in the soils of northern Ghana is crucial. Yet every year, farmers burn. Nobody takes responsibility for it, always blaming other people hunting bush meat.
Every year, farmers should rotate the crops planted in a certain field. If one year, he/she plants maize, the next year soy beans then maybe a type of bean. In Ghana, that bean would be the black eyed pea (scientific name). Intercropping can also be done and the next year, switching what was planted in each row. This is to avoid depleting the soil of particular nutrients year after year and use other crop plants to replenish the soil of nutrients taken from the previous crop. Maize requires high levels of nitrogen, so planting legumes (i.e. nitrogen fixing plants) the following year can replenish nitrogen supplies in the soil for the following year of maize.
Trees are beneficial for so many reasons: shade (when the leaves or on the tree and when they are shed, water retention, maintaining soil structure and nitrogen fixation (either from the roots or when the leaves cover the soil and begin to disintegrate). Trees can be used along the land’s border or interspersed throughout the land at appropriate distances (so as not to compete with each other). For places like northern Ghana, where most plants struggle to survive in the dry season (as mentioned above), trees are the way to go on the non-negotiable of residue retention / crop cover. In Zambia they have a tree called the fertilizer tree, Faidherbia albida, where in the rainy season it sheds its leguminous leaves and ‘blooms’ in the dry season. We do not have this tree in Ghana but we do have the neem tree, which, although not leguminous nor does it drop it’s leaves during the rainy season, it can be easily pruned so as not to inhibit the sun from getting to crops. Also, moringa is a great, fast growing tree that could be used for all the reasons listed at the start of this paragraph and more. The leaves can be harvested for human consumption and seeds collected for sale. In Ghana, a small bucket can fetch between 10-15 cedis ($3.75). While not a lot in dollars, it can have significant impact for a family in northern Ghana.
I hope it has been made clear, that soil conservation is at the heart of CA; land preparation and maintenance are of utmost importance. I ask that all these principles be borne in mind in the upcoming posts in this series. They all tie in together and have made me wonder why this is not the only way agriculture is done.
Links on the ‘internet of nature’: