Water Chestnut Cultivation, Farming Practices

Introduction to Water Chestnut cultivation

Water Chestnut (Trapa natans) is one of the important minor fruit crops grown in India. It is an aquatic nut crop grown in the tropical and sub-tropical region as a submersed plant community. It also thrives in the soft nutrient-rich waters in lakes, ponds, and streams with a neutral to slightly alkaline pH level. Water chestnut is also known as Singhara and Water Caltrops.

A step by step guide to Water Chestnut cultivation

In India, Water Chestnut is most commonly used as an edible nut. The kernel of Water Chestnut contains a large amount of protein up to 20%, starch (52%), tannins (9.4%), fat (up to 1%), and sugar (3%),  minerals,  etc.  It is a good source of fiber and vitamin  B along with  Ca, K,  Fe, and  Zn. Apart from these  Water Chestnut has numerous curative and supplementing properties also. So, they are known as cooling food and are excellent to beat the heat of the summer season. Also, a mixture of Water Chestnut powder with water is used as a great reliever of cough.

Different varieties of Water Chestnuts

The major types of Water Chestnuts are Chinese, European, and Indian.

Chinese Water Chestnuts

There are other Chinese Water Chestnuts (such as the ones termed “European” below), but the type described here are the ones most of us are most familiar with today. They aren’t nuts they’re “tubers” the root-like part of a rush-like plant that grows in freshwater. (Granted, their brown skin is kind of chestnut in color.) The almost turnip-shaped tubers grow near the bottom of the pond or stream and harvested from the water with forks. Rich in fiber, these Water Chestnuts have a starchy but neutral taste to them and have a satisfying crisp and firm bite.

European Water Chestnuts (water caltrops, Jesuit nuts)

This Water Chestnut variety is called “Trapa natans” by botanists, so you can see right away by the very different scientific name that it’s a different creature from the “Chinese” Water Chestnuts. For starters, it is a nut. The nuts are a problem in themselves and these “chestnuts” have the same color as chestnuts, they aren’t anything as benign as the chestnuts that kids bean each other with. They have sharp, strong barbed-spines on them that can pierce even leather-soled shoes, and make beaches and wading quite dangerous.

Indian Water Chestnuts (singhara nuts)

These Water Chestnuts are a good deal like the “European Water Chestnut”, but they have fewer spines on them. Many farmers in India are encouraged to grow them as cash-crops and they’ll grow fish in a pond for half a year, then these chestnuts in their ponds for the other half. And they are considered to be tastier than the “Chinese Water Chestnut” which is a tuber. In India, they are known as singhara (or Singara) nuts.

Water Chestnut plant propagation

Generally, the propagation of the Water Chestnut plant is commercially done by seeds.  The fully mature nuts are placed in containers with little water to germinate the Water Chestnut seeds.  The sprouted chestnut seeds are sorted out and broadcast in the nursery tanks.  At the beginning of monsoon,  the seedlings are lifted from the nursery tanks and planted in the pond,  at a  spacing of 1-2meters or 2 to 3 meters when the soil of the pond is fertile.

The climatic requirement for Water Chestnut cultivation

The water temperature level of  12-15°C  is necessary for the fruit to germinate while  20°C  is required for the development of the flower.  The temperature range throughout the year is dependent on continental climatic conditions, which is the high temperature during spring and summer season, and low in winter is beneficial for the successful production of the Water Chestnut crop.

Grown areas of Water Chestnut cultivation in India

Water Chestnuts grow throughout the East of India – West Bengal, Jharkhand, and Bihar are examples of such regions. Bihar, in particular, cultivates the Water Chestnut fruit extensively in its districts of Darbhanga, Madhubani, and Samastipur.

Soil and selecting the land for cultivation of Water Chestnut

As  Water Chestnut is an aquatic plant, the soil does not play so much important role for its cultivation. But it is found that water chestnut gives better crop yield when the soil of the water bodies is rich, friable which is well manured or fertilized.

Select land that is gently sloping without low spots where water can collect and pool. This is important for chestnut trees since they are prone to “wet feet” and will not survive without a good surface and under drainage. Chestnut trees grow best in well-drained, deep, fertile, moist loam to sandy loam soil with good aeration and a soil pH level of 6.5 to 7.2. They prefer soils and climatic conditions that peach trees and stone fruit require. Do not plant in heavy clay soils and soils with a pH level above 6.5. If the pH level is high, annual applications of agricultural sulfur and a sulfur-based fertilizer like ammonium sulfate instead of ammonium nitrate must be applied. This will help to reduce the pH level. Modifying the pH is a slow process and the soil needs to be tested and adjusted annually.

Nutrient management for Water Chestnut fruit cultivation

The water chestnut plant requires some specific nutrient elements for better growth and development.  Fertilizer with a moderate amount of poultry manure is essential for higher yield.  The nutrient uptake by a  crop that yielded  4,700kg/ha were nitrogen  108kg/ha,  magnesium  37.5kg/ha, and calcium 6.9kg/ha. But it requires little application of phosphorus and potassium. It can thrive well under a pH level of 6.5 to 7.2.  Growers from different parts of the world use dolomite  (a  form of lime that contains magnesium)  to adjust pH levels in which one of the most important works during nutrient management practice. Application of 30 to 40 kg of urea in per ha area of the pond after about a month of transplanting and again after another 20 days is highly recommended.

The growing requirement for Water Chestnut fruit cultivation

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he Growing requirement for Water Chestnut fruit cultivation.
The Growing requirement for Water Chestnut fruit cultivation.
  • The Water Chestnut plant requires full sunlight for good growth, and water with rich organic content but a low concentration of salts.
  • On a larger scale, the Water chestnuts are grown in flooded fields like rice.
  • These fields are located below a water source like a dam so that the water level can be maintained with gravity flow. They can also be grown on dam and pond edges but only if the water level is controllable and also stable.
  • It is recommended that Water Chestnut plants are first grown in a low nutrient nursery plot and transferred when stems are about 300 mm tall. Then, this reduces the growth period in ponds by up to 6 weeks.
  • Tops can be trim if they are too tall at transplanting. Care must be taken at the time of transplanting so that seedlings kept moist but not submerged.
  • The soil must be kept flooded with 100mm to 300mm of water throughout the growing period. A greater depth of water is tolerated by the Chestnut plants but they do not prosper Water should be drained off before harvesting. When filling containers with soil it must be ensured to allow for 100mm of water.

Water Chestnut planting and production

The edible part of a water chestnut fruit is the corm which grows below the waterlogged soil.  To prepare a container for planting put 20cm sand, soil, or potting mix which has been enriched with well-rotted down manure, some garden lime or dolomite, and blood and bone. Plant the corms in early spring 5 cm deep into the chosen spot. Plant about 2 corms to the square meter, overcrowding the corms will dramatically reduce yield.

A rich, sandy, well-limed loam with a pH level of 6.5 to 7.2 is needed. Well composted animal manures or organic fertilizers can be used to improve fertility. Keep the corms well-watered and allow growth to reach 10 cm high before flooding 7-10 cm deep. Maintain this depth for the whole growing season which must be at least 7 frost-free months. Bruce grows his water chestnuts in cracker dust with added sand, seaweed, and granular diatomaceous earth.

Fill the container with water so it is a few centimeters above soil level and allow it to soak well for a few days.  Drain off the excess water and allow it to sit for a couple of weeks so the manure and fertilizers have time to breakdown a bit.  In ideal growing conditions 1 corm will multiply to 100 in a good growing season, some sources recommend in a square meter you should plant 1 corm others 2 some say to plant them 30cm apart.  Plant corms 10cm deep in the soil, keep the soil moist but not submerged until their shoots are about 20-25 cm high, then fill with water to about 10cm above soil level.  This water level must be maintained until the corms are ready to harvest.  It takes about 8 months from planting until harvest.  When the weather starts to cool in Autumn the leaves of the water chestnut will start to go yellow color, which means they are almost ready to be harvested, drain off or remove the water leaving the corms in the wet soil for another month until the shoots die back and are straw-colored.  If you don’t want to harvest them at this time remove the dead plant leaves and the corms can be left under the soil for the cooler months (a few cold nights will sweeten them) but come spring they will start to shoot again.  In containers harvest the corms by hand to avoid damaging their delicate skins; the corms will be in the top 10cm of the soil.

Select a couple of best corms to store for planting in a few months when the warm weather arrives, keep them in a dark cool to a cold place in cold water or damp sphagnum moss or damp sand.  Corms that have been frozen or dried out will not grow and to store for later use seal in plastic bags in the bottom of the fridge, they will also keep well in cool damp sand.  Bruce prepares a large about 20cm plastic pot with mulch or shredded paper in the base.  This covered with a thin layer of seaweed.  Lifts the water chestnuts with minimal root disturbance and places them in the pot.  This is covered with a thin layer of seaweed. This is covered with a thin layer of seaweed and then more shredded paper and mulch.  The pot is kept barely moist over winter and then places the pot in deep shade under a tree.

Water Chestnut growing in containers and ponds

Water Chestnut fruits are easy to grow in any container that holds water, such as an old bathtub or Styrofoam vegetable box. The plants can be grown in a plastic-lined trench (above ground, or dug in), or in large plant pots that are submerged in a pond. Chestnuts can be grown in floating rafts on ponds.

Hydroponic Water Chestnuts

Water Chestnut fruits are grown hydroponically, using buckets and a suitable medium such as permite plus vermiculite. Then, the buckets can be kept topped up with an old nutrient solution from other crops. Growers report having success with different types of hydroponic systems for growing Water Chestnuts. You might choose the ebb and flow system, a tray table system, or a deep flow hydroponic system. Flood and drain is another one that can be effective and you have to make sure that plant roots don’t get submerged for too long, otherwise, they may rot. You need a strong stable growing media to hold the Water Chestnut plant in place while it develops. Some growers recommend things like gravel or rock wool. An ideal temperature range for hydroponic Water Chestnuts is described as around 25-32°C. These plants need around half a year to develop under high light. Like other types of plants, Water Chestnut plants can be vulnerable to small flies and other pests. Growers want to apply neem oil or some other natural substance to plants to counteract this type of damage.

Reproductive behavior of Water Chestnuts

Seeds germinate in the spring with each seed producing about 10 to 15 rosettes and each rosette capable of producing up to 20 seeds. The Water Chestnut plants start to produce hard, nut-like seeds in July with the seeds ripening in about a month. Overwintering of populations is accomplished when the mature, greenish-brown seeds sink to the bottom where they can remain viable in the sediment for up to about 12 years. The plant spreads by the rosettes detaching from their stems and floating to another area, or more often by the nuts being swept by currents or waves to other parts of the lake or river.

Harvesting and yield of Water chestnut

Harvesting of this nut is done in September and continues up to November.  For the harvesting stage, specially made rafts are used by the growers. The yield of fresh nut range between 2500-3800 kg per hectare area of the pond which could be increased up to  5000 kg per hectare by applying about 50 kg of urea per hectare of the pond along with eradication of weeds. Water Chestnut fruit yield is about 2500-3500 kg per hectare.

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Commonly asked questions about Water chestnut cultivation

Can I grow water chestnuts at home?

Water Chestnuts are easy to grow in any container that holds water. Water Chestnuts can also be grown in floating rafts on ponds.

How much time to grow water chestnuts at home?

Water Chestnuts need controlled irrigation and 220 frost-free days to reach maturity.

Are water chestnuts healthy?

Water chestnuts are a great source of fiber. Summary Water chestnuts are nutritious and contain high amounts of fiber, potassium, manganese, copper, vitamin B6, and riboflavin. Most of their calories come from carbs.

Are chestnuts and water chestnuts the same thing?

Both Chestnut tree and Water Chestnuts are delicious, but they are entirely unrelated and belong to two different plant families. Tree chestnuts belong to the beech tree family, which are forest trees and shrubs. The Chestnuts are shiny brown color nuts that develop from catkin-like flowers. The Water Chestnut belongs to the sedge family, which is rush like plants that live in boggy or aquatic places. Water Chestnuts are underground stem enlargements called corms, and the plants have to be dug up to harvest the corms.

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