Talking SOP September 2012 [PDF, 673.84 Kb] - Tessenderlo Group

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Groundnuts: a highly nutritious crop with a variety of uses Groundnuts, or peanuts as they are often called, serve two major purposes. About half the world’s production is industrially processed for oil; the other half is for direct consumption providing a valuable source of protein, fat and minerals. Many third world countries are among the top 10 groundnut producers and it is clear that the crop generates a valuable cash income for many poor farmers in the developing world, especially in Sub-Saharan Africa and Asia. Since groundnuts are often grown in arid conditions, their fertilization requires special attention. Main groundnut cropping and production areas Country Production Area (1,000 tons) (1,000 ha) China 16.000 4.650 India 5.500 5.300 United States 1.649 444 Nigeria 1.550 1.245 Burma 1.300 850 Indonesia 1.250 750 Argentina 1.050 325 Sudan 850 1.000 Senegal 700 1.000 Others 5.606 5.353 Source: USDA The groundnut (Arachis hypogaea) is in fact a leguminous crop forming part of the “bean” family (Fabaceae). The oldest specimens, discovered in Peru, are 7,600 years old, however it is believed that the first groundnuts were cultivated in Bolivia, Paraguay or Brazil. Later, the crop spread throughout Mesoamerica and its Spanish conquerors brought the first groundnuts to Europe. European traders then introduced them into Asia and Africa. Finally, African slaves brought the crop to Northern America in the 1700s. Groundnut growth and harvesting Groundnut seeds are lodged just a few centimetres below the soil’s surface and the young plants usually emerge within a few weeks of planting. Flowering starts 30 to 40 days later. After self-pollination of the flowers, the stalk below the fertilized plant ovary elongates and curves downward towards the soil while the flowers wither. Later the stalk tip enlarges and pod and seed development begin. The nut then matures over the next 9 to 10 weeks. The pods ripen 120 to 150 days after the seeds are planted. Groundnut harvesting generally takes place when the foliage begins to yellow. The plants are separated from the roots and are allowed to dry for several days, enabling the nuts to lose slightly less than a third of their original moisture content. After the nuts have dried sufficiently they are threshed, removing the pods from the rest of the bush. If the crop is harvested too early, the pods will be unripe. If they are harvested late, the pods will snap off at the stalk and will remain in the soil. Groundnut cropping Groundnuts should be grown in rotation with cereals such as maize or sorghum, which have been well fertilized, because they respond better to fertilizer applied to the previous crop rather than to the groundnuts themselves. Little nitrogen fertilization is normally required since atmospheric nitrogen is fixed in the root nodules. Basal applications of fertilizers are broadcast prior to planting. Depending on soil tests, recommended application rates vary from 10-30 kg N/ha, 40-90 kg P 2 O 5 /ha and 40-90 kg K 2 O/ha. Additionally, 250 kg CaO/ha is often applied at bloom to prevent the formation of empty shells. K-Leaf TM SoluPotasse ® GranuPotasse ® Standard SOP
A loose sandy soil with good drainage and a pH ranging from 5.3 to 6.5 is preferred. Potassium - a vital element Potassium is a key element for the plant’s metabolism. It contributes to the development of proteins, enzymes and vitamins as well as to plant photosynthesis. Furthermore, potassium plays an essential role in transport systems within the plant and it improves water use efficiency. It is therefore necessary to ensure adequate potassium availability in the field through soil testing. If soil testing reveals there is little potassium available, there will be a need to apply additional potassium fertilizer. In light soils it is recommended that potassium is applied in two split doses to minimize loss due to leaching in heavy rainfall conditions. (DAP), and organic pesticides containing very little sulphur, as well as the low presence of sulphur in the soil in regions where groundnuts are produced. Sulphur deficiency is characterized by stunted growth and young leaves are small and yellowishgreen. Nodulation and pod formation is restricted and maturity of the seeds is delayed. In cases of severe deficiency, the leaves become papery. SOP for higher yield and improved quality Sufficient potassium fertilization may improve the number of pods per plant, but also their size and pod filling, as shown in the graph below from a trial in China. Fig. 1: Effect of K fertilization on pod size and number Fig. 2: Effect of K fertilization on oil yield and content Pod weight No. pods Yield Content Potassium deficiency in a groundnut plant Lack of potassium causes stunted plants with small branches and reduced vigour. The leaves of potassium-deficient plants do not grow normally and appear irregular in shape. In mature leaves a yellowish-green color can be observed, spreading from the leaf apex along the leaf margins to the middle of the leaf, while the areas around the vein remain normal. In severe cases, the leaves appear dry and scorched at the edges and the leaf surface is irregularly chlorotic. Symptoms usually appear within five weeks of planting. Because of leaching, potassium deficiency is particularly prevalent in light soils. Source: Northern China, 1995 Additionally, groundnuts are known to be a chloride sensitive crop. Since excessive chloride may impede growth and decrease yield, use of potassium chloride (MOP) as a potassium source is best avoided. Potasium sulphate (SOP) provides the plant with sulphur, thereby improving both yield and quality. Further experiments in China on sandy soil with low sulphur content for example indicate a 8% higher yield when SOP is used compared to MOP. Trials conducted in Egypt in 1999 indicate that SOP not only improves yield, but also the oil content of the pods is higher. As illustrated in Fig. 2, application of 180 kg K 2 O/ha increases groundnut oil content by 9%. Source: Egypt, 1999 Cost-effective improvement: foliar SOP application Recent studies demonstrate the benefits of foliar application of SOP in groundnut production. K-Leaf, Tessenderlo Group’s new, rapidly dissolving SOP, has been designed especially for foliar application. Foliar application of K-Leaf not only cures or prevents potassium and sulphur deficiency efficiently, but can also enhance potassium uptake by the plant roots. Fig 3. Effect of SOP foliar application on yield Mt/ha Sulphur deficiency in a groundnut plant NP NPK 100% soil Source: ARC Egypt, 2011 NPK 50% soil + 2 foliar app. Sulphur also plays an important role in the metabolism of groundnut plants. It is essential for the synthesis of proteins, plays a key role in chlorophyll formation and assists in biological oxidation-reduction processes. In recent years, sulphur deficiency in groundnut production has become an issue due to the use of high quality fertilizers, such as di-ammonium phosphate Additionally, efficient absorption of both potassium and sulphur through the plant’s foliage improves yield. Interestingly, trials in Egypt demonstrate that higher yields can be achieved by combining half the usual dose of SOP applied to the soil with two foliar applications, compared to a full dose soil application. K-Leaf TM SoluPotasse ® GranuPotasse ® Standard SOP
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Talking SOP September 2012 [PDF, 673.84 Kb] - Tessenderlo Group

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