Peanut (Arachis hypogaea L.) or groundnut has been a popular crop in the Philippines. It is considered one of the major field legumes grown by farmers but its production has been low and erratic. Among the provinces in the Philippines, the top producers of peanut are Isabela, Pangasinan, La Union, Quirino, Cagayan, Ilocos Norte, Ilocos Sur, Aurora, Albay and Iloilo. However, the Cagayan Valley region produced almost half of the country’s total peanut production.
In the Philippines, peanut can be grown throughout the year provided inputs, especially the water requirement are adequately available. In general, dry season crop (October-January) gives higher yields and beans of better quality than the rainy season crop.
The recommended peanut varieties in the Philippines are as follows:
1. UPL Pn-2 – 104-111 days
2. UPL Pn-4 – 105-110 days
3. UPL Pn-6 – 105-110 days
4. UPL Pn-8 – 100-110 days
5. BPI Pn-2 – 97-101 days
6. UPL Pn-10 – 98-100 days
7. PSB Pn-2 – 101-103 days
8. PSB Pn-3 – 103-104 days
9. ICGV 8848 -120 days
10. ICGV 88392 -120 days
11. ICGV 88406 -120 days
Peanut requires a well-prepared field to attain good seed emergence. Thorough land preparation is also necessary for proper development of pods and effective weed control. Plow and harrow the field 2-3 times at an interval of 7 days. Each harrowing consists of 2 passing.
In dry season planting, straight furrows are made at a distance of 50 cm from higher elevation of the field going down to the lower elevation.
A well-cultivated soil allows easy penetration of the peg and development of the pods. Plowing the field 15-20 cm deep will completely cover the plant residues and reduce losses from stem and pod disease caused by Sclerotioum rolfsii. About two to three alternate plowings and harrowing will be sufficient to put the soil in good tilt for planting.
Only full mature seeds from recommended varieties with high germination rate and vigor, that are free of weed seeds and other foreign materials
Peanut is planted as soon as the furrows are made, probably early in the morning or late in the afternoon. Planting shelled peanut seeds is the standard practice but some farmers use the old practice of planting unshelled pods. A 50-cm row spacing gives the highest bean yield. However, for convenience and relative ease of weeding, cultivation and spraying without significantly affecting yield, 60-cm row spacing is recommended. Planting maybe done mechanically or manually. Manual planting is accomplishes either by drill method (sowing of seed singly and evenly on shallow laid-out furrows or by the hill method
Method and Time of Cultivation
Cultivation not only loosens up the soil for better root and peg development of peanut but also controls the growth of weeds. Yield of peanut is greatly influenced by the combination of off-barring and hilling up. Likewise, hilling up is better that flat cultivation because the former provides loose soil around the base of the plant for the developing pegs. Hilling up done 35-40 days after plant emergence or just before flowering results in higher than hilling up after flowering.
The traditional method of weeding is still done which is a combination of cultivation and manual weeding. Weeding should start as early as 2 weeks and not later than 6 weeks to maximize bean yield.
Peanut is a crop that fits well in many multi-cropping schemes. In the Philippines, peanut is planted between rows of corn at varying spacing. Corn plants spaced at 100 cm apart with one row of peanut intercrop produce the highest grain yield. However, one row of peanut in between 2 rows of corn spaced at 75 cm is found to be the best intercropping combination. Intercropping peanut with sugarcane or other annual crops such as mungbean, soybean or upland rice is highly profitable. Peanuts may also be intercropped with cassava, okra and maybe planted between rows of coffee.
Peanut is relatively drought tolerant. Most field legumes need critical period of water during germination, flowering, pod development and pod filling stages. When peanut is planted during rainy season, irrigation is generally not needed, however, when planted during the dry season especially in early October, supplemental irrigation is not needed in most instances. Normally, there is still residual soil moisture sufficient to support the vegetative and reproductive process of the crop from October to December. The late dry season planting in February needs supplemental irrigation. Three to four applications maybe enough; first application is at planting for seed germination; the second weeks after planting; the third at midbloom stage and the fourth at pod filling. The average amount of irrigation water ranges from 4-50 mm per application.
In the absence of soil analysis, a 30-40-40 fertilizer recommendation is practical which is equivalent to 1.33 bags of urea (4-0-0) or 3 bags of ammosul (21-0-0), 4 bags of solophos (0-20-0) and 1.33 bags of muriate of potash (0-6-0). If soil inoculant is used, only one-half of the recommended fertilizer is needed.
Peanut should be harvested at the right stage of maturity. Harvesting is normally a very manual and labor intensive operation which varies from 6 man-days/hectare to 15-23 man-days/hectare.
In small-scale production, harvesting is done manually by pulling the entire plant or passing a native animal-drawn plow or both sides of the row to loosen the soil.
The maturity of peanut can be determined by the following indications; (a) gradual withering and yellowing of the leaves of majority of the plants which are more noticeable during dry season planting; (b) expected maturity date of variety ranges from 90-110 days depending on the planting season; (c) maturity is indicated by hardness of most of the pods, darkened veins of the inner portion of the shell, vascular strands on the shell becomes more distinct and plump pinkish full grown kernels.
Farmers aerate and dry newly harvested peanut in the field which can either handpick or strip/thresh pods from the vine by beating. To shake off pods from the vines, farmers repeatedly strike pods against a hard surface. Manual threshing of wet peanuts is accomplished at the rate of 11 kg/hr per person while that of half-dried peanuts at the rate of 30 kg/hr. per person.
For wet-season crops, farmers usually strip/thresh the pods immediately after harvest so that they can be immediately dried to the desired moisture content to prevent deterioration. For dry-season crops, stripping is delayed because farmers windrow the plants in the field to reduce plant and pod moisture content.
Picking is done is such a way that the peduncle does not go with the pod. The pods are then washed and the inferior, immature ones are separated from the mature and sound pods. The parent plant or vines are usually either left in the field to decompose or kept and used as animal fodder.
Sun drying is the traditional and most commonly used drying method by farmers which is considered as the cheap method but very dependent on climatic condition. It will take 2-5 days depending upon the weather condition to dry the crops left in the field under the sun. In general, drying is done twice within the chain of postharvest operation; initial drying prior to threshing and final drying before shelling.
When peanuts are grown as second crop, windrow frying in the field is sometimes followed by aeration in small shaded huts prior to threshing and final drying as practiced in Cagayan Valley region.
Peanut should be shelled carefully to avoid scratching, splitting and rupturing of the seed coat, breaking of the cotyledon, or separating one or both of the cotyledons from the embryonic axis. Traditionally, farmers shell peanut manually. Manual shelling of sundried and flatbed dried peanuts gave similar average recoveries of 68%. Hand shelling is the preferred method of obtaining peanut seeds which protect seeds from being broken.
After shelling, processors manually clean and sort peanut into reject, broken whole nut and unshelled nut. The common practice to winnow peanut by using crircular bamboo tray “bilao” and hand pick the nuts. Substandard kernels and other impurities are manually sorted from good kernels done by separating the split, damaged, moldy and other defective kernels.
Peanuts are stored in unshelled form. The shells act as a natural protective covering of the seeds against mechanical damage and insect infestation. Farmers use sacks but some store peanut in open concrete pits under their farmhouse, bamboo baskets. For shelled peanuts, traders use bags piled to a maximum of 7-8 layers only. Shelled peanuts are usually stored 2 months and six months only for the unshelled peanut.
Sources: bar.gov.ph/agfishtech/crops/peanut.asp. Sept 2009. Palomar, M.K. 1998, Peanut in the Philippine Food System: A Macro Study. In: Peanut in Local and Global Food Systems Series Report No. 1, Rhoades. R, PI and Nazarea, V. CoPI, Department of Anthropology, University of Georgia, USA. Photo: birdingstore.com