Cultivation practices of carrots
Carrot is a semi-hardy crop which is cultivated all over the world. It is the common name used in Zambia for Daucus carota. Since it is a semi-hardy crop, carrot require cool weather for it to perform well. Carrot need long days and vernalization of roots. Despite carrot being able to tolerate higher temperature of tropical and subtropical climate, the crop require an optimum temperature ranging from 7.2 degrees Celsius to 23.9 degree Celsius and 18.3 to 23.9 degrees Celsius respectively. Below are cultivation practices of carrot.CultivarsNantes, early gem, early horn, chantaney, imperators, golden heart and zeno
Timing in planting of carrot is very important in achieving best yields. However, the time of planting carrot seems to vary in relation to locality where cultivation is happening. For example, in Georgia commercial carrot cultivation occur in two times of the year; spring in the north and fall in the south. Conversely, in Maryland cultivating of carrot starts from March 20th to April 30th for the crop purposed to harvest early, and May 1st to July 15 for late harvesting. On the contrary, growing of carrot in Wisconsin happens beginning mid- April to early June (colquhoum paet al, 2017). However, in Zambia carrot yield best when it is planted from March to April. The main idea is to allow carrot pass through cool weather for them to increase sugar content.When carrots emerge from the ground, they tend to be very small such that they are easily blown off by wind. The wind damage the crop and thus reduction in crop stand per foot. Planting oat in the carrot field helps preventing of carrot from wind damage. These oat is removed at a late stage of carrot growth by selective herbicide.
Generally, the best cultivation practice of producing carrot happen in light deep, loose, fertile soils that have good drainage. Good drainage helps in reducing the cases of high water table saturation in the growing season while light soil promote growing of sizeable root dry matter. Compacted soil or very heavy soil should be avoided because they restrict they growth of carrot roots.
Spacing depend on the purpose of cultivating carrots. Carrots that meant for processing can be planted at inter-row spacing of 18 – 36 inches allowing 16 plants per foot, 18 – 36 inches inter-row for fresh market and cut and peel of which 6-8 plants per foot are sown and for both processing and fresh 1.5 -2 inches apart and 4-6 seeds per foot is recommended (brust et al, 2015). Generally, a common spacing of carrot is 15 -30 inches between rows on flat and 3 – 4 rows on a bed pf 3 -4 feet. Lime and fertilizerLime: use dolomitic limestone (maintain pH 5.6 or higher in organic soils. At least pH 5.8 in other soils.NitrogenPhosphate and potashOrganic matterAmount to apply (Ib/a)Yield goalAmount P2O5 to apply (Ib/a)Amount of K2O to apply (Ib/a)<22.0 -9.912010020 – 30 ton/a4524010 -20>2080IrrigationEarly irrigation helps establish stands in hot, dry weather and is particularly important in the seedling stage. Carrots should not be under water stress. Irrigating carrots at 10-12 days interval in winter and 5-6 days in summer is best practice (Nair et al, 2014). However, irrigation should cease just prior to harvesting.
Pests and diseasesThe possible pest type that affect carrot crop include Nematodes and leaf diseases. Generally control of Nematodes most occur at planting. Applying furadan at sowing time helps prevent severe infestation of nematodes. On the other hand, although leaf diseases are attack carrot plants, the know diseases of this type are those caused by alternaria and cercospora. The possible control measure of leaf disease include applying of dithane M-45 (25g/10lts) or benlate 6g/10lts.HarvestingHarvesting Carrot takes place at fully ripen of the secondary umbels and the tertially ones begin to turn brown. This is the time when the carrots have attained 2cm of diameter. In order to remove carrot roots from the soil under commercial cultivation, a range of machine harvesters are readily available for use. The typical harvester is occasionally used when harvesting crop meant for processing (Seaman, 2016). When hand pulling is used, the plants are pulled and place them in piles of 4 – 5 plants Yield The expected yield of carrots ranges from 30-40tons per hectare with top management.
CULTIVATION PRACTICES OF IRISH POTATO
Irish Potato also called solanum tuberosum, is a vegetable crop that is grown for its tubers. The tubers can be eaten cooked, processed into chips or grind into potato powder. Because Irish potato is a cool season crop, have moderate tolerance to frost. This means that tuber formation is much favored by short days that could be 10 hours or even less. However, active growth occurs at temperature of 24 degrees Celsius, whereas tuberization at 20 degree Celsius.
The cultivars grown in Zambia include pentland Dell, bpi, pimpernel, up-to-date, majestic, jelly, valor, Madison, Georgina and Rumba.Soil preparation Preparing soil is very important in ensuring health growing of plants. Generally, the type of field practice determine how the soil would be prepared. If the Irish potato is opted for plant on flat, then, using moldboard plough to obtain 60cm deep soil would be essentially used. The soil should then loosen using harrow to obtain good soil of 20cm. Preparing soil some months before plant season offers some benefits. The soil prepared in advance facilitate warmer soil temperature and gives enough time and labor to the grower (communication service, 2013). The soil should be medium texture, loamy with an optimum pH range of 5.0 to 5.5. Kraal manure can be added to improve the organic content by applying 50 tons per hectare.
Planting time of Irish potatoes vary with the locality or region. However, there some similarities especially for the Irish potato that is grown under irrigation. For example, in some countries planting time starts from February and ends in April, which they call winter crop (SNV, 2016), while in Zambia extends to May/July (Mathai, 1984). Meanwhile the single rain-fed or summer planting begins in October/ November.
Irish potato seed
There are two types of planting materials used under commercial Irish potato production. Although the most known planting material are tubers, potato seed referred to as True potato seed (TPS) (Chand et al, 2014), are now used to start potato plants. These seeds usually come from South Africa and Zimbabwe but the practice has not yet widely spread. The use of potato tubers has long stayed. These tubers vary in size depending on the desire of the grower. The tubers are sprout under daylight conditions before planting. Sometimes potato seed (tubers) are forcefully subjecting to constant temperature (30 – 35 degrees Celsius) while covering tarpaulin in moderate sunshine just to make them sprout.
Irish potatoes are planted in two ways; either on flat or on ridges. If planting has to be on flat, use a ridge to make furrows where potato tubers would be placed at the depth of 10 – 15cms. Application of side fertilizer should follow. After planting the soil should kept moist.If potatoes are to be planted on ridges, it is important to make ridges of 60cms wide, and should have loose soil with depth 20cms. However, when higher yields and large tubers is anticipated, then a more profound planting depth and wider ridges give a more good condition to develop than shallow planting (communication services, 2013:7).
There has been varying spacing used in Irish potato cultivation. However, what affect the spacing is the consumer demand, market needs and economic return to growers and marketers (communication service, 2013). For this reason, (Bok et al, 2006) conceptualize different spacing in relation to seed required per hectare. however, (SNV, 2016) argued and stated that the inter – row spacing should be 900mm while intra-row 300mm. Mathai (1984) echoed or agree with SNV’s statement by indicating spacing of 60-90cm between rows, and 20 – 30cm between plants. However, despite this variation, the standard spacing should allow a plant population of 33000 – 37000 per hectare.
Earthing up is important for two reason; the first is that it helps in controlling the weed, and the second one ensures that tubers are not exposed to direct sunlight which could make the tubers start greening. As essential as it is, Irish potatoes should be earthing up twice during its grow season. The first earth up is at 15 – 25 cm potato plant height and the just at tubering stage to cover the tubers.Seed rateOne hectare needs seed ranging from 1200 – 2500 kilograms of tubers. However, only 200 grams of true potato seed would be used in a hectare.
Fertilizer and manure
Fertilizer typeQuantity (kg)/haN120P240K120Azospirillum & phosphobacteria2Farm yard manure15000IrrigationIrish potatoes do not require more frequent watering. The most common irrigation is once or twice in the week depending on the cultivars, relative humidity, solar radiation, day length, length of growing season, and other environmental factors.
PestCommon pestControl measuresAphids PirimoreTuber moth Azodrin , use also parasitic wasps. Earth up tubers properlyLeaf wormsCarbaryl, malathionCaterpillarMalathion LaybirdMalathionCutwormsDursban Nematodes Furadan, mocapDiseasesDisease Control measuresPotato virus YPlant certified disease-free seed potatoes Eradication of aphid weed hostsDestruction of volunteer potato plants as they may host the virusEarly and late blightSpray protective chemicals like dithane M45, copper oxychlorideBlack scurf
Plant health seeds
Dry and soft rotUse preventive measuresMild mosaic (virus X)Destroy affected plantsHarvestingHarvesting of potatoes depend on the variety planted. Early maturing variety may takes about 100 days. Most of the varieties take 120 – 150 days for them to attain maturity. Whatever the case may be, harvesting potatoes takes place when 95 per cent of leaves fall off and skin become firm and does not peel off easily. The methods employed in lifting tubers include semi-manual in which harrows are dominantly used as well as mechanical such potato harvesters.
On average Irish potatoes can yield from 20 – 30 tons per hectare. However, under top management produces 30 – 40 tons per hectare.
CULTIVATION PRACTICES OF RAPE
Rape, so called in Zambia, is generally a cool season crop. It belongs to brassicaceas family also referred to as cruciferael. This is the family to which ordinary cabbage, Chinese head, cauliflower, broccoli, Brussel and sprouts also belong. In Zambia, rape or Brassica napus could be grown throughout the year. However, maximum growth, flavor and texture occur at temperature range of 10 – 15 degrees Celsius more than it would in hot or summer season. Soil preparationSoil preparation is important for best emergence as rape seeds are very small. Thus reducing seedbed soil to fine tilth will create a better environment that can allow seeds emerge with less difficult, and could increase the germination percentage. Soils that form hard pans should be avoided or have the hard pan break by ploughing deeper. This will in turn facilitate creation of weed free seed bed.
Sowing / planting
As stated early, sowing of Rape seed could happen at any time of the year especially vegetative production. However, considering three (3) types of areas will give a guide on when to best sow rape seeds. Bok et al (2006) reveals that in cool areas December/ January, mild areas January to March and warm areas February to April are favorable sowing time, respectively. During the time of sowing, the farmer has two possible ways of sowing to choose from. The he could either make a nursery in soilless trays or direct sowing of the seed. If nursery method seems appropriate, then 2 grams of rape seed per square meter should cover 50 square meters, and this should be well protected from pest and bad weather. Nursery method requires that the rape seedling transplanted at 15 centimeters of height. Sometimes trays may not be available, instead a ground made seed bed is an option. Sowing of seeds in this type of seed bed will follow spacing of 15 cm between rows in drills and seeds should be place at 0.6 centimeters depth. When seedlings are almost 10 – 15 centimeters high, reduce watering to harden seedlings for them to acclimatized water stress. However, if direct, 3 – 5 kg of rape seed could be used to cover a hectare. Some of the seedlings should be removed or thinned when reached 15 centimeters high to attain the required spacing. The recommendation is that seed beds be 90 -120 centimeter.
Transplanting of seedling takes place when they are 15 centimeter long or at after 6 weeks from sowing. Spacing of seedling depend on the variety. Nevertheless, the spacing of 60cm x 40cm, 40 cm x 15cm, 60cm x 10cm and 45cm x 7.5 – 15cm may be used. The important aspect in spacing is that there must be a space for machine operation.
The frequency of watering the crop depend largely on soil type and prevailing weather condition. In cool season 7- 9 days interval can help the crop to grow well, while in warm dry weather 4 -5 days can keep the crop growing. However, 8100 cubic meters of water per hectare is require within 17 weeks. In average soils 30mm of water per irrigation is equivalent to 300 cubic meters per hectare.
Fertilizer and manure requirement
Cultivation of health rape requires relatively heavy proportion of fertilizer. Like any other brassicaceae member, rape is a heavy feeder crop. It requires 700kg – 1000kg of compound – S or C as basal dressing, while 200 -300kg of ammonium nitrate is appropriate as a regular top dressing a month after basal. Splitting of top dressing in three parts at an interval of 14 – 21 days will benefit the crop to produce better yield.
PestControl measureAphidUse systematic insecticide like Karate, lambdscopeCabbage semi-loopersMalathion Diamond back mothThuricide, malathion, orthene 75 SPDiseasesDiseaseControl measureBlack rotSoft rotHarvestingIn rape cultivation harvesting takes place 60 days or 2 months from planting. Harvesting mainly is by hand in which leaves are pushed downward and snapping them off or by a sharp knife. Harvesting in rape has not been mechanized.Yield Rape can yield up to 50 – 75 tons per hectare within continues harvesting of four months of picking. However, the average yield 22 tons per hectare. Moreover, in Zambia some writers claim that rape could yield 2000 – 3000kg/ha (Mathai, 1984).2 constraints limiting the establishment of large scale commercial and export production of carrot, Irish potato and rape in Zambia
Establishing a Commercial production of carrots, Irish potato and rape is seemly not easy not easy in Zambia. Despite the agro-ecological environment been able to support the growth of these crops, there has been other factors which constrained their large scale production. Below is the major limiting factor to commercialize the stated crops.
Irish potato Factors limiting commercializing this crop includeInadequate knowledge on irish potato cultivation by farmers High input cost especially seed.Little interest by farmersFarmers have adopted seasonal production ( dependence on rain-fed, due to lack of finances to buy irrigation equipment Capital is very low among farmer which cannot support the commercializing of the crop.
Uneconomic land units.
Farmers have small portions of land which cannot facilitate the expansion or transition process to large scale production.Access to credit permits a farmer to enhance efficiency by overcoming liquidity constraints which many affect their ability to apply inputs and implement farm management decision on time.
Constraints include Lack of Seed availability and high cost. If available they are of poor quality and costLack of access to reliable water source for croppingInadequate trainings on pest/diseases like prevalence of bacterial wilt.Inadequate funds to purchase proper crop chemicals leading to problematic pest/disease control. Lack of appropriate and adequate training and extension support. Many agricultural activities as well as extension and trainings focus on main staple crops like maize and very little on supporting horticultural crops like potato and carrot.Lack of entrepreneurial and marketing skillsHigh demand of quality in market channels. Rape Factors limiting commercializing of rape includeMarket accessDecline in soil fertility mainly due to continues cultivation without adequate replenishment of mined nutrientsLack and inadequate cold chain storage for very perishable vegetables like rape whose shelf life is very short.The huge cost of setting up of commercial irrigation system which is not equivalent to the low return per sale.