Vegetable crops offer a good source of income for both small- and largescale farmers. But it takes so much more than placing a seed in the soil and harvesting the plants at the end of the season. It takes care, diligence, nutrients, and knowledge on caring for crops.
Now that we have reached the end of our vegetable planting guide, there are still a few key points to keep in mind. These points are crop rotation and the crop calendar. Understanding these two points will enable you to find a production process that works best for you, either by rotating a specific selection of crops over a certain period, or by planting multiple crops in one season while considering crop and soil health.
There are many benefits to planting various crops at the same time. It means that you can deliver more than one type of vegetable to market during one season, ensuring that there isn’t a surplus that is wasted or unpurchased. It also helps you be less reliant on the market price of only one type of crop. Seeing as the supply and demand per vegetable differs from season to season depending on a good (or bad) harvest, the inconsistent price can have a negative effect on your income.
Crop rotation and the crop cycle
Crop rotation is a cultivation practice of growing a variety of crop types in succession on a specific plot or area over a few growing seasons.
To rotate your crops in one year, you can divide the area you want to cultivate into four sections. The area is divided into four because there are four crop types to keep in mind. Alternatively, you can rotate crops over a period of four years (or growing seasons). One crop per crop group is then planted in each of the four areas. The following season, you will need to plant a different type of crop in the bed. You will continue to do this until you have completed the cycle.
Alternatively, a one-crop system can be used in which case the area that is being cultivated will be handled as a single seedbed. The cycle will then also be followed until it is completed over four years.
The four crop groups to keep in mind are as follows:
Category 1: Legumes
This group consists of legumes or vegetables that make pods. They add nitrogen to the soil, an important nutrient that helps form plant proteins and enzymes. These types include green beans, peas, soya beans, chickpeas and peanuts. If it has a pod, it is from this plant category.
Category 2: Shoots
Shoots, or leaves, are the vegetables that grow leaves which humans consume. These plants usually require a lot of nitrogen. Spinach, chard, lettuce, cabbage and broccoli are all part of this category.
Category 3: Roots
Root vegetables are light feeders. They generally require more potassium, a vital element for optimum plant growth. The vegetables in this category are anything harvested from below the soil, such as carrots, radishes, onions, garlic, turnips, and beetroot.
Category 4: Fruits
They extract a lot of phosphorus from the soil. These vegetables have fleshy structures in which they store nutrients and usually seeds, but tubers such as potatoes or sweet potatoes also fall under this category. Under this type of vegetable you will also find tomatoes, eggplant, maize, peppers, as well as cucurbits such as cucumbers, pumpkins, and melons.
The benefits of crop rotation for vegetable planting
- Now we can take a closer look at the benefits of crop rotation:
- Reduces pressure from pests that feed on one specific crop type in the soil
- Prevents soil exhaustion by adding or subtracting different nutrients
- Can help weed control
Pest are reduced through crop rotation because most pests and diseases are crop specific. This means that they feed on vegetables from a specific group. By replacing the crop with a different type effectively starves the specific pest when the insects cannot attack the new plants.
Some growers also question whether the soil can truly benefit from crop rotation, but conservation farmers have already proved the positive effects that crop rotation has through improved yields. There is without a doubt less pressure on the soil nutrients when the combination of nutrients that are being used is different from one season to the next. Certain plants such as legumes also place nitrogen and carbon back into the soil. This also influences the types of weeds that grow on the field. All in all, crop rotation leads to a reduced need for expensive fertiliser and pesticides.
With improved soil health, you can look forward to improvements in your yields and lowered costs on agricultural inputs. However, remember that this improvement is not a process that happens overnight and you may only see improvements after a few seasons of following these practices.
For the plants to benefit the most from crop rotation, it is important to cycle the crops in a specific order. Legumes are always followed by leaves, then fruit and ending with roots.
As important as it is to plant crops in succession, your plants will not grow properly if you don’t plant them at the required times. To find the correct planting dates, you can look at the articles for each individual crop as available on www.proagrimedia.com.
For a quick overview, you can refer to the tables below. You will need to know whether you live in a summer or winter rainfall climate. You will be able to determine this by considering when your area receives its most rainfall. In Southern Africa, rain between November and March means it is a summer rainfall climate, whereas rain from May to August means it is a winter rainfall climate.
The two tables below indicate when to plant your crops.
You will note that during June and July, no crops are planted. Due to winter in the Southern Hemisphere, there is little growth for any plants, and the microbial activity in the soil is also lower. Rest your soil in these months.
To prepare your soil to rest postharvest, you can either plant a cover crop or use mulch to keep the moisture in the soil during the winter. If you would like to know more about mulching, you can read our article Plants perform much better with mulch on our website, www.proagrimedia.com.
Cat, D. (2022). How to practice crop rotation (benefits explained) ~ Homestead and chill. Available at: https://homesteadandchill.com/croprotation-benefits/.
Crop rotations. (2020). Available at: https://rodaleinstitute.org/whyorganic/organic-farming-practices/crop-rotations/#:~:text=Crop%20rotation%20helps%20return%20nutrients,increase%20biodiversity%20on%20the%20farm.
Food Garden Projects. n.d. Available at: https://www.ufs.ac.za/supportservices/departments/service-learning-at-our-universityhome/links-for-community-projects/food-garden-projects.
Lebo, N. (2015). Saving your soils with crop rotation. Available at: https://www.fix.com/blog/three-yeargarden-crop-rotation-plan/.