Originating in China, soybeans are known for being one of the first-ever crops to be cultivated by human beings. Chinese farmers are estimated to have cultivated this plant since 2 500 BC, although today, they contribute only about 10% of the world’s soybean production.
In South Africa, the upcoming soybean harvest is predicted to reach over 1.8 million tonnes this year, with the biggest contributions set to come from the Free State, Mpumalanga and North West. While soybeans are used in the manufacture of oil and protein, most of the country’s soybean production goes towards animal feed.
Danie Bester, a maize, sunflower and soybean farmer from Mpumalanga, says soybeans are the ideal rotation crop, allowing maize farmers to save money on fetilisers.
“The biggest [reward] from having soybeans in a system is, as soon as you farm the maize crop that follows the soybeans, you get some extra nitrogen credits from the soybeans. They bind through the nodules that they have so you can reduce the amount of nitrogen fertiliser on your crop. You’re getting about 20 to 30kg of free nitrogen from your soybeans.”
Bester, whose farming business is called Deepwater Trading, first learned about soybean farming from his father. He says that the wide range of cultivars available to South African farmers today makes it much easier to farm with the plant. He says when his father started their farming operation, soybean cultivars were not as common as they are right now, nor as great.
“Then, in about 2002, I told my father [that] I think it’s time to go back to the soybeans. You can’t do monoculture in farming. That’s not a good practice. You have to mimic nature and you have to go to different species.”
Choosing cultivars
There are plenty of soybean cultivars to choose from in South Africa, like SNK 500 (24), Sonop (150), and PAN 626 (1412). For Bester, the cultivars from South America are the ones that tend to work best.
“I’m a firm believer in the genetics that we’re receiving from Argentina and Brazil. Those countries are leaders when it comes to soybean production. So, we get a lot of genetics from them. At the moment, I’m a big believer in the Donmario genetics.”
When it comes to choosing cultivars, farmers have to resign themselves to selection via trial and error, Bester explains.
He adds that farmers need to plant more than one variety to manage risk. “Also, each soil type has got a variety that you have to plant, but at the moment the Argentinian type and the Brazilian type genetics; I find them to be superior to some of the other genetics coming from the USA and some of the locally produced varieties.”
Soil is king with soybean farming
Soybean cultivars are adapted for different types of soil, but the most critical aspect of farming with them is the state of the soil, says Bester.
“A lot of people ask me [about the soil] and I tell them ‘listen, it’s easy. You just need fertile soil’.”
Bester says with sandy soil your crops will be more prone to nematode infection. This is why farmers with sandy soil need to choose varieties that have some resistance to nematode infection.
“Whereas, if you’ve got higher clay soil where nematodes aren’t that big of a problem, then you don’t need a variety that has any nematode resistance to it.”
Bester explains that finding the best variety for your soil involves some trial and error, but that there are some general rules that apply.
“Plant your soybeans on soil with good drainage. Soybeans don’t like too much water as they have rhizobium which has to do some nitrogen binding. [Nitrogen binding] is dependent on the amount of oxygen in the soil as well.”
The nitrogen fixation is really important for the success of your soy yields, he adds.
“If you’ve got soils that are prone to being saturated, you won’t get that biological nitrogen fixation, and then you’ll get really poor performance. And the deeper the soil, the better the yields will be. But choosing between sandy and clay soils doesn’t matter. You’ll just have to find the right variety for that soil. [Your] internal drainage is really important.”
Also critical to the success of your soybean crop is soil fertility, says Bester.
“If the soil is good, then the crop will be good, [so] you should just worry about the soil. If you get that right, then it’s actually quite easy to grow soybeans. Don’t feed soybeans through their leaves. Just feed them through their roots.”
Soybeans are extremely weather-sensitive
South Africa’s soybean planting season starts from the beginning of October to the beginning of November, and planting after the end of November is considered late.
Bester says he starts his planting season around 15 October, as soil temperatures are crucial to soybean production. “You have to wait for the soil to warm up. You have to get to at least 16°C, and 18° is even better. If the temperature is below that, it’s going to cost you yield.”
Bester cautions that soybeans are sensitive to day length, which is why planting them at the right time is crucial.
“That is what triggers them to start flowering. So if you plant them too late, you will get less vegetative growth and you’ll have small plants. They’ll try and compensate with bigger leaves to catch as much sunlight as possible. Unlike with maize, that needs heat units to produce, soybeans actually want sunlight for a certain amount of hours.”
This is why planting earlier in the season makes more sense, because planting too late will produce good-looking plants with a diminished yield.
Bester’s biggest challenge is that erratic weather can easily ruin his soybean crops. He says that weather that is too hot will push the plants to abort their flowers and pods.
“So you don’t want a climate with very high temperatures that is too dry. Also, on the other hand, you don’t want too cool temperatures and too humid-type climates either, because then you run into high disease pressure.”
The ideal temperature is between 23°C and 28°C during the crop’s peak flowering time.
“The weather has the biggest influence on yield. When you go down to KwaZulu-Natal where you get a lot of misty mornings and a lot of dew in the late summer, then you’ll run into some disease. But if you go to Limpopo where there’s really dry weather, then you will get pod abortion. So, you’ll have to find that comfortable middle.”
Harvest time for soybean farmers takes place between March and April. Bester says that there are varieties that allow harvest up until the first week of May.
Pests and diseases
Like most crops, soybeans are vulnerable to diseases. Bester explains that timing of the diseases is linked to the weather.
“There might be a few varieties that has some degree of protection against some certain foliar diseases, but in South Africa, unfortunately, our seed companies – I don’t know if they’re not willing to do it or if they can’t do it – don’t give you a rating for which soybean varieties are maybe less prone to get something like white mould.”
White mold or Sclerotinia stem rot is the worst disease affecting soybeans at the moment and it can occur anywhere in the country, says Bester.
“That is where a good foliar protection programme with fungicides comes in, so that you can get protection from that. And usually, because of white mold being the worst disease you can get, the stuff that you spray for it will protect you against all the other, lesser diseases like rust or powdery mildew.”
When it comes to pests, Bester says bollworms tend to be a big issue for soybean farmers. These insects eat the seeds out of the pods and even eat the flowers.
“So that is something that you have to manage throughout the year. And that’s also weather dependent when the outbreaks will be. These insects can cause big losses, but with the new genetics coming out that’s resistant to bollworms, that’s going to make a lot of stuff a lot easier to manage.”
Some advice
Bester’s advice for aspiring soybean farmers is simple: Start small, educate yourself, and choose accredited cultivars.
“As with everything, if you experiment, start on a small scale. Get as much information as you can and never, never, never ever believe everything that the first guy who comes along tells you. Every guy wants to sell you their product.”
He encourages aspiring farmers to rather talk to those who have made a success of their soybean production.
“When you’re trying stuff, do it on small scale. And when it comes to soybeans, don’t just buy seed from anyone. Make sure that you start out with good quality seeds with a high germination factor. If you do those things right, then you’re set for big success.”
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