By growing oyster mushrooms, you can help fight North India’s stubble-burning problem

There is something about growing your own food that nurtures the soul as well as the stomach. While most urban gardeners start with balcony or window-sill herbs, such as lime or curry leaf, in a pot, perhaps moving on to cherry tomatoes and bok choy, their efforts rarely graduate to the main course. This can be changed with the high-protein, shell-shaped oyster mushrooms. Not only are these easy to grow for novice kitchen gardeners, they have a satisfyingly meaty taste, are quick to cook, and lend themselves to a variety of dishes and cuisines.

Oyster mushrooms can be bought online, but at approximately Rs 600 a kilo, they are expensive – much more so than button mushrooms, which are standard vegetarian fare today. They taste better than the button variant, have a high protein content (about 10% to 30% of their dry weight), and are rich in vitamins, minerals and essential amino acids (such as lysine and tryptophan) – all incentive enough to try and grow them at home.

According to Geeta Arunachalam, who has been conducting workshops on their cultivation since 2010, these mushrooms can go some way towards mitigating the annual malaise of stubble burning in North India. The satellite images of Punjab and Haryana, aflame after harvest, are so disturbing that all viable uses for the stubble should be encouraged. The best growing medium for oyster mushrooms, as it happens, is straw, although the spawns will also sprout in waste paper and dried leaf shreds.

Arunachalam, who is in her early sixties, is a retired biology teacher and school principal. Passionate about the environment, she has worked with a number of schools on tree plantation, recycling waste and mushroom cultivation. Arunachalam’s crash course in growing oyster mushrooms, titled Taste from Waste, is supported by the Ministry of Environment. She specifically targets schools and gardening groups in and around Delhi for her workshops – a demographic that is perhaps most receptive to ecological concerns.

Oyster mushrooms are far more commonly consumed in South Indian cities like Bengaluru. This may possibly have something to do with some of the cities having the ideal temperature for the mycelium to sprout and grow – between 10 and 30 degrees Celsius.

But there are ways its cultivation can be encouraged in the North as well: village co-operatives run by women in the region could extend the growing period by building small sheds at the edge of fields where stubble is available. The walls of the shed could be made with straw blocks and covered with a coating of clay and cow dung. A simple wooden or metal framework with a thatched straw roof would be ideal. Arunachalam recommends covering the inner walls with burlap sacking. This can be sprinkled daily with water to maintain the recommended humidity – between 50% to 70%. The straw walls will insulate against extreme temperatures, besides utilising waste stubble. The mushrooms have a shelf life of seven days, so the entire supply chain will need streamlining.

I am going to detail a few do-it-yourself steps for the home gardener. These are based on Arunachalam’s tried-and-tested methods.

The weight of spawn to straw at 2% ratio is the simplest technique. You will need about 5 kilo straw. This should be be well-dried and yellow in colour, with no rotting black stalks. Straw is usually available in the market for about Rs 3 per kilo. It needs to be cut into strips, between four and five inches in length, washed and dried, so that it is only mildly damp.

The receptacle for the straw can be a discarded flour or potato sack, a large garbage poly bag, a hollow log, a throwaway or broken perforated plastic colander or green netting used by gardeners. Whatever the receptacle, it has to be disinfected with a mild solution (2%) of formalin. The sacks need to have half-inch holes cut into them for aeration.

The spawn containing the mycelium is available at government outlets and online, and cost about Rs 100 per kilo. These last in the refrigerator for two months. A 5 kilo bundle of straw will need about 10 gm of spawn sprinkled throughout, mixed well, just like you would toss a green salad with dressing. Do not pack it too tight – give the mushrooms space to grow.

After sprinkling the spawn, the bag should be tied securely at the top, and if possible, suspended. The first harvest will be after about 30 days. At least two other harvests, at an interval of 10-14 days, will be possible. The oyster mushrooms will need to be cut with a knife.

Arunachalam usually gets a harvest of about 2.5 kilo of mushrooms to 5 kilo of straw. By this time, the straw usually decomposes and can be used as compost for potted plants. One or more sacks can even be kept in a sheltered balcony under tarpaulin or a makeshift burlap wigwam, if space is limited. In fact, Arunachalam recommends a table-top – approximately four feet by three feet – which can hold about six sacks. These can be suspended under the table once sprouting starts. Button and shitake mushrooms can also be grown in a small area, once one is familiar with the method.

Oyster mushrooms make a wonderful stir fry, with chopped shallots, ginger-garlic and soy. Red bell peppers and broccoli florets can be added to make a more colourful plate. They can also be used to make pickles, soups, sandwiches, cookies, muffins, baguettes, koftas and other continental and oriental dishes.

Geeta Arunachalam’s recipe for Mushroom Cutlet

Ingredients
2 large potatoes, peeled and cut into small pieces
1 cup chopped oyster mushrooms
1/2 cup green beans, chopped
1 egg
1/4 cup green peas
1 1/2 cups bread crumbs
1/2 teaspoon garam masala
1/4 cup vegetable oil for frying
2 green chillies, finely chopped

Method
Put the potatoes, mushrooms, green beans and peas in a pot with 1/4 cup of water. Cover and cook for 10 minutes on low heat (with salt to taste) until the vegetables become tender.
Dry the vegetables, transfer to a bowl and mash with a potato masher.
Add the egg, the bread crumbs, garam masala and salt into the bowl with the mashed vegetables. Out of this, make the patties as per requirement.
Heat the oil in a large shallow pan over medium heat, and fry the patties until they are golden.