An ounce of information
Published on 04/10/2023 in Peanut Farming
Peanuts are an ideal farming crop, and are grown extensively in tropical and subtropical regions. Here are the basics for delivering a high-quality harvest
The humble peanut is one of the top oilseed crops grown in Asia. Peanut farming in India is widespread, with India being the second-largest producer after China. An annual herbaceous plant, peanuts can reach up to 50 cm in height and belong to the Fabaceae family and Arachis genus. Peanut farming is a core activity of many commercial producers across tropical and subtropical regions.
Peanuts are widely used as an ingredient and are typically processed by roasting, grinding into peanut flour, or crushing to extract peanut oil. They are rich in essential nutrients: A typical 100-gram serving contains 550 calories, 40-45% oil and 25% protein, as well as generous levels of dietary fibre, several B vitamins and vitamin E, and several dietary minerals such as manganese, magnesium, and phosphorus.
The “oil cake” obtained after the oil has been extracted from peanuts makes a useful organic manure and animal feed, and contains nitrogen, phosphorus, and potash. Peanut farming is also an effective cover crop or rotation crop option for areas exposed to soil erosion – making groundnut farming a profitable commercial enterprise for many.
Climatic conditions such as temperature and rainfall significantly influence the growth of peanut crops. Warm and moist conditions are favourable for healthy growth, whereas a cool and wet climate results in slow germination and seeding, as well as an increased risk of seed rot. Peanut crops will not tolerate long periods of frost, severe droughts, or stagnated water.
Peanuts require a relatively high temperature and a frost-free period of about 160 days. Anything above 35°C inhibits growth, and below 15°C growth stops entirely. For rapid emergence, the soil must be above 21°C, and the best germination and seedling development occurs at around 30°C.
Moisture is another critical factor for successful peanut production. Planting must be done on moist, warm soils to speed up the germination process, with wider planting rows advised in low-rainfall areas.
A significant level of rainfall is particularly essential during the flowering, pegging, and pod formation stages, in order to ensure maximum yield and high-quality peanuts. Although peanuts are t
|How much rainfall do peanuts require?|
|Pre-sowing operations (preparatory cultivation)||100 mm|
|Flowering and pod development||400-500 mm|
Typically grown in areas with 600-1,500 mm of rainfall, 1,250 mm is optimal.
Peanuts do best in full sunlight but can tolerate partial shade as well. When planted in the shade, peanut leaves will become larger and produce fewer reproductive organs, but yield will typically not suffer.
Peanuts grow best in well-drained, yellow-red or red-coloured, fertile, sandy-to-loam soils with a pH range of 5.5 to 7.0. Saline soils are not suitable because peanuts have a very low salt tolerance.
The peanut plant produces horizontal runner stems which in turn produce flowers at each node. These flowers self-pollinate and trigger peg formation in groundnut plants which penetrate the ground – this is where the peanut pod is produced. As a result, the topsoil must have a low clay content of less than 20%, and a loose structure that the peg can penetrate easily.
The seedbed must be deep, typically 900-1,200 mm, without compaction layers, to accommodate the peanut plant’s root system, and to ensure sufficient drainage. Suitable soil forms are Avalon, Bainsvlei, Clovelly, Hutton, Pinedene, and Glencoe.
To ensure your peanut cultivation will be effective, it’s important to know which groundnut grows in which soil, and to do a thorough soil test, especially when growing peanuts from seed.
Crop rotation is crucial for groundnut farming, as it helps rebalance soil nutrients and reduce the prevalence of soil-borne diseases, nematodes, and weeds. Maize, sorghum, pearl millet, or small grain crops are ideal follow-on crops, and you should avoid planting peanuts after tobacco or cotton.
The balanced use of fertilizer and manure delivers the phosphorus, potassium, calcium, sulphur, and magnesium needed for peanut growth. Before applying fertilizer, it’s important to assess your current soil nutrient status.
When using chicken manure, 10-12 tons per hectare is suitable, or 20 tons per hectare for decomposed farmyard manure. Manure should be mixed into the soil at least one month before crop sowing.
Seed layout and plot design in peanut farming
Arrange your peanut crop plots in four 4-metre rows, with 30 centimetres between rows and 10 centimetres between plants to effectively test cultivation treatments.
Preparation for sowing your peanut farm
1. Prepare your field maps, indicating the distribution of rows and spacing, and your treatment plan.
2. Select your seeds: Bold kernels shelled just one week before sowing deliver a superior emergence rate, a higher volume of primary branches, leaves, and dry mass, and a higher pod yield.
3. Coat your seeds before planting with either Thiram® (a.i. 5 0 % @ 3 g kg -1 seed) or Bavistin® (a.i. 5 0 % @ 2 g kg’ 1 seed) to control pathogens and reduce seedling diseases.
4. Space your seeds depending on the peanut variety: For bunch varieties 330,000 plants/ha is recommended (about one plant per 30 x 10 cm); for semi-spreading and spreading varieties 250,000 plants/ha (one plant per 40 x 10 cm) is recommended.
5. If sowing by hand, separately packet the seeds for each row; for machine sowing, arrange those packets by groups of rows for continuous sowing.
Sowing peanut seeds
1. The start of the rainy season is an ideal time to sow your peanut seeds.
2. Examine the soil before sowing to ensure optimum moisture content, and irrigate if required.
3. Place the seeds 5-6 cm deep in the soil, and compact the soil around the seeds to ensure firm moisture contact. A seed drill with packing wheels is best for ensuring uniform germination and reducing groundnut sowing time.
4. When sowing manually, it’s best that the same person completes the plots in each particular block to reduce variation.
Irrigation in peanut farming
|The negative effects of dry soil |
● A lower crop growth rate: A water deficit in the first 67 days delays rapid fruit growth by 10 days and decreases yield.
● A water deficit during the flowering and pegging stages results in bigger yield losses than stress at any other growth stage.
● A water deficit during fruiting results in unfilled pods and less calcium concentration in the hull and seed.
Effective irrigation ensures plenty of water is available in the upper 60 cm of soil, supporting high-yield and quality crops. During peak water-use periods your field may require 3-3.5 cm of water every five days to maintain soil moisture above 50% of field capacity. Irrigation intervals can be extended to 7-10 days during other periods.
During the pre-flowering stages, a moderate water deficit followed by irrigation will increase pod yields by 18-20%. During pod formation and seed development, soil water depletion should be maintained at 25% or -0.6 bars. This means that the upper 30 cm of soil should appear and feel moist and the plants should not wilt from lack of moisture during the afternoon.
Weeds can be hugely damaging to peanut crops, especially during the first 45 days of growth, and can reduce yield by 30-60%. Mechanical and chemical weeding is therefore key.
Harvesting your peanut crop
Premature harvesting of peanut pods lowers your yield, oil content, and the quality of your seeds. Equally, late harvesting can result in increased Aspergillus flavus infection (yellow mould) and aflatoxin contamination.
Once you have identified that your peanut crop has reached optimum maturity, take one of the following three harvesting approaches:
1. Apply sprinkler irrigation for one hour and manually pull the plants.
2. Provide light surface irrigation 2-3 days before harvesting and use a blade harrow to cut the plant roots 12-15 cm below the soil surface. Then manually pull the plants.
3. If irrigation water is scarce, use a plough or tractor-driven digger to loosen the soil, and then manually remove the plants.
Once harvested, your plants should be stacked in the field for a few days to dry in the sun – before you strip the pods – as reaching a 6% moisture content will reduce the development of aflatoxin. In cloudy weather, two days at 27-38°C in an air dryer may be more effective than field drying.
After cleaning and grading, store the dry pods in gunny sacks and stack them up to 10 bags high in separate stacks so that air can freely circulate. The bags should be piled on wooden planks to avoid damage from dampness. Dusting the bags with 5% Lindane® will protect the pods from many storage pests.
Marketing your peanut crop
Finally, it’s time to sell your peanuts. Local peanut mills or government markets are great places to look for the best deals.
With the basics covered, you can make a clear plan for your peanut farm. There’s plenty more to learn about peanut farming: With the right knowledge, you can deliver the best yield when it’s groundnut harvesting time.
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