Maximum yield with rainfed soya beans

A wise farmer adapts his production methods to his farm’s environment. Gerhard Keeve, an award-winning soya bean producer, shares his approach to obtaining the maximum yield under rainfed conditions with Lloyd Phillips.

Maximum yield with rainfed soya beans
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Gerhard Keeve has continued building on the soya bean production knowledge his father, AP Keeve, and other soya bean pioneers in his area have built up and shared. Gerhard’s late father AP was among the first farmers to grow soya beans in the Scheepersnek area of northern KwaZulu-Natal. AP started farming alone on the farm Zaaifontein in 1980, until Gerhard joined him in 1991.

At the time, AP was cropping maize and soya beans on an annual rotation. He and about 10 other farmers in the Scheepersnek area were the first to grow soya beans there, and had formed the Scheepersnek Soyabean Study Group. When the annual Super Soya Competition was launched in 1992, AP and Gerhard were two of its first entrants.

AP’s forward thinking on the value of soya bean production and his approach to maximising soya bean profitability paid off in 2002 when he won the competition’s award of Highest Gross Margin – Dryland (North). Three years later, AP passed away, but would be proud to know that last year, Gerhard won Highest Yield Dryland (North) and was runner-up for Highest Gross Margin – Dryland (North).

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Farm facts
Zaaifontein is 660ha with about 40ha irrigated and 200ha rainfed. White maize and soya bean crops are produced in summer on a 2:1 year rotation. Around 90ha is under black wattle timber, and 300ha is natural sourveld grazing for Gerhard’s 130 commercial Simbra-type breeding cow herd and followers.

The farm’s 20-year average annual rainfall is 850mm, with midsummer temperatures around 30°C, peaking at 37°C. Winter temperatures drop to -3°C, with about two weeks of intermittent frost. The western half of the land is predominantly well-drained Avalon soil with a grey A horizon and a yellow B horizon, about 1m deep and overlying a soft plinthic layer. The organic matter content is low and the clay content is between 25% and 30%. The eastern half is mainly red Hutton soil over 1,2m deep, well-drained with a 40% clay and low organic matter content.

Tillage and stover use
Gerhard uses conventional tillage, but neither rips nor ploughs and prefers the more conservation-orientated method of chisel ploughing and a tined implement to prepare the seedbed. With diesel prices sky-rocketing, he is considering changing to no-till production.

“I don’t grow winter crops and leave the stover on the land for livestock to graze from June to August, until just before the first rain in mid-September,” he explains. “Maize stover provides around 4t/ha dry matter (DM) and soya bean stover up to 1,5t/ha DM. I remove the cattle before the first rain to avoid hoof compaction on wet soil.

“If it rains earlier, I remove them and keep them off until after the next harvest. My average rainfed white maize yield is 6t/ ha to 7t/ha and I sell the grain to a nearby mill. The long-term average rainfed soya bean yield varies from 2,3t/ha to 2,5t/ha.” After removing the cattle from the stover and before planting soya beans, Gerhard burns about 50% of the remaining maize stover.

This is done land by land, on a rotational basis every four or eight seasons, depending on his needs. While he prefers retaining stover on the land to boost the organic matter content in the soil before planting soya beans, fire prevents the germination of volunteer maize plants and makes soil preparation easier.

After the first single rainfall of over 20mm, Gerhard works the land with a chisel plough at 200mm to loosen the soil for good penetration of rain ahead of planting. This ploughing also kills small weeds that germinated after the burning, or came through the unburnt stover.

Time to plant
“I plant the first maize in early to mid-October, and soya beans from late October to early November,” Gerhard explains. “To plant soya beans, I put in a 3,4m-wide Vetsak seedbed preparator immediately ahead of the planter to create a level seedbed and kill small weeds.

“I then use a four-row John Deere 1750 conservation vacuum planter to plant 420 000 soya bean seeds/ha for a germination rate of 350 000 plants/ha to 380 000 plants/ha. “Annually, I use about 10% newly bought seed, with the rest being my own retailed seed. About 50% is PAN 538 RR, 40% PAN 737 RR, and the 10% bought seed is PHI 95Y20 Roundup Ready.”

For Gerhard, the appeal of PAN 538 RR and PAN 737 RR is that these tried and tested cultivars have high yields. A 140-day to 150-day growing season means that they are ready to harvest before the maize. Research has found that medium-length growing season soya bean varieties are best suited to northern KwaZulu-Natal. These two varieties also have good tolerance to soya bean rust.

The PHI 95Y20 RR planting is Gerhard’s trial to compare growth performance and yield with that of PAN 538 RR and PAN 737 RR. So far this newer cultivar is doing well and Gerhard is considering using more in the future. He normally inoculates all of his soya bean seed with SoyGro, but is using both SoyGro and Stimuplant during the present (2011/12) season to compare the two in terms of yield.

Gerhard standardises an 80cm inter-row spacing in all his crops to eliminate adjusting his implements and harvester. While many other soya bean farmers prefer a 91cm spacing, his plants canopy lower at about 70cm, shading out many weeds and this also reduces competition for moisture and nutrients between the weeds and the soya beans.

Nutrients & pest control
“While many farmers don’t apply fertiliser to their soya beans at planting, I apply Omnia 2:3:2 liquid fertiliser at 130l/ha through the planter about 5cm-8cm to the side of, and about 25mm below, the seed planted at 50mm depth. This provides about 180kg/ha N:P:K, a valuable nutrient boost to the seedlings. They grow vigorously in the first three important weeks.”

To cut production costs, and because of a clean, prepared seedbed, Gerhard does not apply a pre-emergence herbicide. But 30 to 40 days after planting, he goes through the lands with a 10m tractor-mounted boom sprayer, applying 2l/ha Roundup and 15g/ha to 20g/ha Classic herbicide to address the persistent morning glory and burr weeds.

He knows from his study group and farmers’ information days that even Roundup Ready soya bean varieties take a growth knock for about 10 days after a Roundup application, akin to a human’s reaction to a vaccination. So, about seven to 10 days after applying Roundup, he applies MaxiBoost containing essential micro-nutrients as foliar feed at 1l/ha to boost the soya bean crop, along with sodium molybdate at 70g/ ha, and 200g/ ha sodium borate to rejuvenate the crop growth.

He says it is pointless applying these nutrients until seven days after the Roundup application, as the herbicide temporarily stunts the soya bean plants, making them unable to absorb the foliar feed. “If I notice pests such as bollworm and looper worm in the crop just before the foliar feed application, I add a pyrethroid pesticide at 120ml/ha to the foliar feed.

About 70 days post-planting, when the first pods are forming, I apply either Abacus at 1l/ha or Amistar Xtra at 300ml/ha to prevent fungal diseases, especially soya bean rust. If the season’s rainfall has been average or above average, I spray either Abacus at 1l/ha or Punch Xtra at 600ml/ha 20 days later. If the rainfall has been below average, reducing the risk of soya bean rust, I take the chance of eliminating the second fungicide spray and hopefully save some money.”

Gerhard harvests soya beans from mid-April to mid-May. To ensure that the crop is ready, he sends samples to Afgri’s Blood River silo for moisture testing. Once the in-field soya bean grain moisture level is below 13%, he uses a Klaas 86 combine harvester with wheat header to bring in the crop and 8t trucks to transport it to the silo.

Future plans
As for the future, Gerhard says, “I look forward to an average 3t/ha yield soon. The technology to achieve this is available. I might start by moving to a one-year maize, one-year soya bean rotation within the next few years. Even the maize yields will benefit from this. “I’ve heard of some very large soya bean processing plants in the pipeline in this country and this will create a sustainable national soya bean market.”

Contact Gerhard Keeve on 083 609 9190 or email: [email protected]