Organic Potato Farming; Planting; Harvesting

Organic Potato Farming; Planting; Harvesting

Today we are discussing Organic Potato Farming, Planting Methods, and Harvesting Techniques.

Introduction to Organic Potato:

Organic potatoes contain a higher content of nutritionally important minerals with higher amounts of vitamin C, iron, magnesium, and phosphorus. These potatoes are best when baked, fried, or used in casseroles. They are organically grown without harmful pesticides, herbicides & fertilizers.

Organic potato production normally fits into a planned rotation on an organic farm. It is possible for a specialist potato farmer to develop organic potatoes on an organic farm. It may be possible to have a single field in organic crop production, providing it operates a suitable planned rotation. Organic potatoes can be adequately isolated from any other potatoes developed on the farm. Potatoes are also a great source of vitamin B6, copper, potassium, antioxidants & dietary fiber.

Challenges of Organic Potatoes:

Organic potato farming has a number of challenges that must be tackled:

• Providing sufficient nutrients.
• Preventing the potato blight.

Soil requirement for Organic Potato Farming:

The soil should be friable, porous & well drained. The optimum pH range for potato farming is 4.8 to 5.4. It is a very cool weather crop. Potato is mostly developed as a rainfed crop. It is cultivated in regions getting a rainfall of 1200 – 2000 mm per annum.

Selecting potato varieties for Organic Potato Farming:

In selecting varieties for organic potato production there are two simple rules:

• Grow potato varieties suited to organic production
• Grow potato varieties which best suit the intended market

Kufri Swarna, Kufri Giriraj & Kufri Chipsona- II are suited for organic farming since they are resistant to blight & nematode.

Organic soil preparation and fertility:

Healthy soil is a source of organic farming. Organic matter in the form of cover crops, compost, or manure creates a soil that is biologically active, with good structure and capacity to hold nutrients & water.

Potato plants require fertilizer, however too much can cause leggy, disease-prone growth. Add generous amounts of compost, or during planting dig in a little amount of natural fertilizer or organic poultry manure. Most gardeners find that the second application of fertilizer, a month or so after planting, helps develop yields.

Seed potatoes:

Potatoes are generally grown from seed potatoes, tubers have specifically grown to be free from disease & to provide consistent and healthy plants. To be disease free, the areas where seed potatoes are grown are chosen with care. In the US, this restricts the making of seed potatoes to only 15 states out of all 50 states where potatoes are grown. These locations are selected for their cold, hard winters that kill pests & summers with long sunshine hours for optimum growth. In the UK, more seed potatoes originate in Scotland, in areas where westerly winds prevent aphid attack & thus prevent the spread of potato virus pathogens.

Planting date for Organic Potato Farming:

The ideal planting date varies widely, depending on region & altitude. The most important factor to find out the planting date is soil temperature. It must be around 8°C or 6°C for pre-sprouted potatoes. The soil must be sufficiently dry.

Planting Depth in Organic Potato Farming:

The tops of seed potatoes must be level with the original soil surface. New potatoes should be earthed up less than ware potatoes to get quick emergence.

Plant the potatoes:

A few days before planting, cut seed potatoes into one or two eyes (buds) on them. Avoid problems by allowing the cut pieces to dry indoors for a day or two, and dust with agricultural sulfur to help keep against fungal diseases.

Plant the seed pieces about a foot apart & two or three inches deep in rows, hills, or raised beds or containers (particularly where diseases have been found before). Prevent sunscald, bitter flavor & tuber greening (indicates a high amount of a poisonous plant alkaloid called solanine). As plants develop, lightly pile soil or thick straw over their lower stems; repeat as needed until 6 or 8 inches of the lower are buried. Potatoes need moisture, but avoid overwatering & reduce diseases by watering early enough in the day to allow foliage to dry before dark.

Phases of growth in Organic Potato Farming:

Potato growth is separated into five phases. During the first phase, sprouts emerge from the seed potatoes & root growth begins. During the second, photosynthesis begins as the plant develops leaves & branches. In the third stage, Stolons develop from the lower leaf axils on the stem & grow downwards into the ground. This phase is often, but not always, connected with flowering. Tuber development halts when soil temperatures reach 27 °C (81 °F); hence potatoes are measured a cool-season, or winter, crop. Tuber bulking occurs through the fourth phase when the plant begins investing the majority of its resources in its newly formed tubers. At this phase, a number of factors are critical to a good yield: optimal soil moisture & temperature, soil nutrient availability & balance, and resistance to pest attacks. The fifth & final phase is the maturation of the tubers: the plant canopy dies back, the tuber skins harden & the sugars in the tubers convert to starches.

Propagation of potato:

The tuber is not only the principal mean for potato propagation but also a main human food source. Potatoes are mostly propagated by vegetative methods (cloning). This is the primary commercial propagation process.

Clonal propagation

Potato tubers are really a modified stem with approximately 70-75% content of water and a remaining 25-30% of dry matter. They have nodes or eyes from which the new development begins. The new stems increasing from each eye are called sprouts.  Sprouts develop from the tuber after a period of dormancy after they are harvested, this varies largely between cultivars. After this dormancy is broken, sprouts grow & when planted, they give rise to the plant stems and from there all the vegetative part of the plant. Underground, lateral shoots called stolons are produced, from which the new tubers will be formed.

Tissue culture

Tissue culture permits a very fast propagation. Each plant has a root system, leaves & terminal points or growth points. There is an apical meristem found at the apex of a potato stem & it also has lateral growth points. Each of these buds has a meristem which allows it to become a dissimilar plant.

The process of this method is very simple. Disease-free plantlets develop in test tubes on a nutrient medium. Each plantlet is cut into three to ten nodal sections after 18-60 days. Each fresh cutting is planted in a new test tube. This must be repeated until the desired number of plantlets is obtained. Plantlets are then removed from the tubes & grown in sterile soil and let them complete their entire growth cycle. Tubers produced are collected & stored to later be sold to growers. This is also the process followed to get certified seeds.

Crop and Soil nutrient management in Organic Potato Farming:

To produce a healthy crop, sufficient soluble nutrients should be available from the soil to meet the minimum requirements for the whole plant. The total nutrient needs of a crop are much higher than the nutrients that are removed from the field when that crop is harvested. All of the roots, stems, leaves & other plant parts require nutrients at specific times during plant growth and development. Restrictions in the supply of required plant nutrients will limit growth and reduce crop quality & yields. The challenge in organic systems is balancing soil fertility to supply these necessary plant nutrients at a time. Soil microbes decompose organic matter to release nutrients & convert organic matter into more stable forms such as humus. This breakdown of soil organic matter occurs throughout the growing season, depending on soil temperatures, water availability & soil quality. The released nutrients are then held on soil particles or humus making them obtainable to crops or cover crops for plant growth. Soils with compost or crop residues provide a food source for soil microorganisms and when turned into the soil, start the nutrient cycle again.

Cover crops in Organic Potato Farming:

Cover crops are crops which are not sown to be harvested, but somewhat to be incorporated into the soil at some point in their growth. Cover crops can be used in the following ways in potato farming:

• As green manures recognized the year before planting potatoes. Increase in yield and quality of potatoes with a preceding cover crop due to improved nutrient cycling & soil tilth. This seems particularly true in warm climates where the turnover of nutrients is rapid but has been reported in cold climates. It is the effect of a preceding cover crop is equivalent to the application of 10 to 90 t/ha of manure, depending on whether the green manure was fertilized or not.
• As catch crops after Organic potato harvest. A catch crop is a crop developed in the same year as the main crop but after the main crop. The main role of cover crops, in this case, is to protect the soil from erosion & to prevent leaching of nutrients unused by the potatoes. It must be tilled in the fall or kept as an overwintering cover crop that will be tilled in the spring.
• As a full-season crop in rotation with organic potatoes. The aim of this practice is generally to increase soil organic matter levels & involves turning on mature plants rather than green ones. It can be part of a non-chemical weed or pest control strategy.

Crop rotation in Organic Potato Farming:

• Avoid soil compaction when harvesting preceding & catch crops.
• Potatoes have moderately high nutritional requirements; moreover, the nutrients must be available shortly after emergence. Hence, potatoes develop, especially well after preceding crops that support the looseness & structure of the soil and leave a high amount of easily degradable organic material.
• Tillage in spring before potato farming reduces the risk of nutrient leaching during the winter months. However, tillage in spring has been often necessary due to frost on soils that have more clay. In the case of early tillage, cover crops that are killed by frost in winter must be cultivated.
• Potatoes leave a lot of nitrogen in the soil, with the potential risk of leaching. For this reason, the succeeding crop to be cultivated must be one that utilizes the nitrogen in autumn, such as winter cereals or green manure with late nitrogen absorption.
• Potatoes normally leave a clean seedbed for the succeeding crop. Ploughless tillage preserves the soil structure & facilitates frosting of remaining tubers to avoid volunteers.

Weed management of Organic Potato Farming:

Weed management can be one of the biggest challenges on organic farms, particularly during the transition and the first several years of organic production. Use an integrated approach to weed management that includes crop rotation, cover cropping, cultivation, and planting design based on an understanding of the biology & ecology of dominant weed species.

Management plans should focus on the most challenging & potentially yield-limiting weed species in each field. However, to emphasize options that do not increase other species those are present. Alternating between early & late planted crops in the rotation can help minimize buildup of a group of weeds with similar life cycles or growth habits, and will also provide windows for a variety of cover crops.

Weed control:

Weed control is the most troublesome field operation facing organic potato producers. As no herbicides are permitted, weed control is accepted out by:

• Choosing fields which have no main weed problems
• Flame weeding of weed seedlings before the organic potato tops emerge
• Mechanical elimination of the first flush of weeds whilst they are still small
• Mechanical weed removal before tops meet between rows
• Limited hand weeding of several large invasive weeds.

Irrigation requirement for Organic Potato Farming:

• Dry soil during early growth promotes a wide root system.
• Early irrigation promotes the conversion of organic matter & thus, the N supply.
• Dry periods during tuber formation lead to a growth check, reduced tuber formation & thus to yield and quality losses.
• From tuber formation in flowering, the water content within the ridge must be kept to a minimum of 50% of the field capacity.
• During tuber growth, sufficient water content is crucial for yield production, particularly from 3 weeks after flowering until maturation.
• It makes sense to irrigate the potatoes directly before harvesting to carry more soil onto the filter belt & thus reduce the risk of damage.
• Drip irrigation is often most effective as it reduces the humidity in reducing the blight risk & is more efficient in terms of water application.

Organic fertilizers used in Organic Potato Farming:

When the soil is arranged for most vegetable crops, fertilizer is blended into the soil. When the soil is top-dressed, the fertilizer assembles on top of the soil. In lieu of growing a cover crop, many organic gardeners top-dress the soil with compost & well-rotted manure, such as poultry manure. Compost helps the soil retain moisture, and well-rotted manure helps to lower the soil’s pH & adds nutrients. The manure and compost can be mixed with bone meal, greensand & kelp meal to round out the pre-planting fertilizer program. The manure mix is added to the soil after planting furrows are dug.

Some of the organic fertilizers used in Organic potato farming:

• Manure
• Cottonseed meal
• Slurry
• Bone meal
• Organic compost or mulch

Read: Organic Compost.

Manure:

• Cattle manure is rich in K; pig manure contains less K but higher amounts of P.
• A dose of manure must be recommended as basic fertilizing. If there is a danger of Rhizoctonia infestation, the manure must be applied to the preceding crop in autumn and not directly to the potatoes.
• It is recommended to use at most 25 to 30 tonnes of manure per hectare. Too large a dose leads to prolonged nitrogen provide, which impedes the maturation of the crop. In the case of dryness or heavy soils, only the succeeding crop might advantage from the nutrients. The regulations limit nitrogen utilize to 170 kg per hectare. 

Slurry:

• Cattle slurry has moderately high K and N contents; on the other hand, pig slurry has higher N & P contents. The nutrient contents of anaerobic digestate depend heavily on the fermented substrates but are normally high in available N; they can be used efficiently in potato farming.
• Slurry must be applied ideally during the preceding crop or before planting. It must be worked into the soil immediately after application.

Bone meal:

Bone meal is a mixture of finely and coarsely ground animal bones & slaughter-house waste products. It is used as an organic fertilizer for plants & as a nutritional supplement for animals. As a slow-release fertilizer, bone meal is mainly used as a source of phosphorus and protein.

Compost:

• Like manure, composted manure & other composts provide a good supply of potassium and magnesium. Composted manure has a considerably lower effect on N supply than fresh manure or rather stacked manure.
• Composts from plant material can be used. They deliver both macro & micronutrients to the soil.
• Compost may offer additional benefits by suppressing phytopathogens in the soil to reduce crop disease.

Pests of Potato Plants:

Damaging pests can work rapidly in a potato patch. Stroll through the plot regularly looking for insects & the damage they cause.

Colorado potato beetle:

This pest is present & working in just about every state. Destroy any potato bugs, see and check the underside of leaves for their orange egg masses. Both the adults are yellowish with black stripes & the larvae, which are dark red or orange with black spots, feed on potato foliage.

Flea Beetle:

Flea beetles are tiny, black or brown & pesky. They chew small holes in plant leaves & can do serious damage fast if they attack young plants. To foil these pests, cover young plants with fabric row covers as soon as set them out. 

Aphid:

These little insects can transmit virus diseases. They suck juices from the leaves & stems of potato plants, injuring them badly.

Wireworm:

Wireworms are the larvae of the beetle. They’re a problem when potatoes are planted in a section of garden that was freshly sodded. Fully grown wireworms are 1/2 to 1 and 1/2inches long. They’re slender, brownish or yellowish white and tunnel into plant roots & tubers, spoiling them.

Diseases of Potato Plant:

Early blight:

Early blight injures foliage & reduces overall yields. Affected leaves develop small, dark brown spots that often grow in size, and which finally kill the leaves.

Late Blight:

Late blight is the reason by the downy mildew, fungus Phytophthora infestans, which triggered the Irish crop failures of 1845 and 1846. The disease first by water-soaked areas on the leaves that turn brown & black as the leaf dies. The disease strikes often during cool, wet weather & may spread rapidly if the weather warms up. Plants can die in a severe case & potatoes can be seriously affected, especially in storage.

Mosaic Virus:

Aphids can extend mosaic viruses, which cause potato leaves to curl & appear almost two-toned (light and dark green). Mosaic occurs throughout the United States & cuts down on the harvest, but it won’t kill the plants. ‘Kennebec’ & ‘Katahdin’ varieties have some resistance to certain kinds of mosaic.

Common scab:

The pathogen infects young developing tubers through the lenticels & occasionally through wounds. Symptoms of common potato scab are quite variable & are manifested on the surface of the potato tuber. The disease forms, some types of cork-like lesions including the surface. Damaged tubers contain rough, cracked skin, with scab-like spots. Severe infections leave potato skins enclosed with rough black welts. Initial infections result in superficial reddish-brown spots on the outside of tubers. As the tubers grow, lesions expand, becoming corky & necrotic. 

Harvesting in Organic Potato Farming:

The potato harvest can begin 7 to 8 weeks after planting when the plant begins to blossom. Potatoes harvested at this time are known as “new potatoes” these tubers are small. Full-size tubers can be harvested when the plant begins to wither & turn brown. The number of days to harvest for mature potatoes depend on the variety grows.

Potatoes are often described as early, midseason & late. Early-season potatoes are complete about 60 days after planting; midseason about 80 days after planting; & late 90 or more days after planting.

Harvest potatoes when the soil is dry to avoid compacting the soil as in the garden. Use a spading fork to raise the tubers; lift from a foot to a foot & a half or more away from the plant to avoid injuring the tubers loosen the soil and lift. Let tubers air dry for a couple of weeks to toughen the skin & then brush away any excess soil before you store them

Storing of Potatoes:

Store potatoes in a dark, cool place at 35° F to 45°F. Store potatoes in a bin, basket, or mesh bag that agrees for air circulation.

The yield of Potato:

15 to 20 tonnes per hectare in a duration of 120 days.

Read: Organic Agriculture.

Last Updated: March 14, 2019