To enrich biodiversity in ecological farming, the number of crop species should be kept as high as possible. This includes planting multiple species together in the same field, sequential planting of different species, cyclical planting of various types of the same species across seasons, alternating companion crops, and cultivating different varieties of each crop. Alongside crop diversity, the diversity of non-agricultural plants should also be maximized.
Native American farmers, around 1,500 years ago, achieved good results by planting corn, squash, and beans together in the same hole. This method, known as the “Three Sisters” farming, remains a model for increasing crop diversity. In this method, bean vines climb up the corn stalks, and squash vines spread along the ground, reducing weed growth. The corn provides a structure for the beans to climb, the large leaves of the squash cover the ground to retain moisture, and the nitrogen-fixing bacteria in the bean roots supply nitrogen to all three crops.
In northern Bangladesh, many farmers still maintain crop diversity by growing five different crops in the same field. When planting potatoes as the main crop, they plant rows of patol (pointed gourd) every five rows, with onions and garlic planted in the same rows, and mustard or flax or coriander sown along the field edges. After harvesting the potatoes in 90 days, the main crop becomes patol, and farmers plant spinach, jute greens, and chili in the same field at the beginning of the Bengali month of Falgun. Once the spinach and jute greens are harvested, ginger and turmeric are planted during Chaitra-Baishakh, along with papaya trees on the field edges.
The above method is a cost-effective model for farmers, although there is room for further increasing crop diversity. For example, if you plan to grow potatoes as the main crop at the beginning of the Rabi season, the crop arrangement should be such that no further tilling is needed throughout the year. Indigenous potatoes can be grown using a thick mulch of straw and leaves, with patol vines or seedlings planted in rows among the potatoes. After harvesting the potatoes, the remaining mulch will support the patol crop. Onions and garlic can be planted in the empty spaces between the patol rows. At the time of planting potatoes, sow seeds of indigenous coriander, mustard, radish, turnip, kohlrabi, carrot, beetroot, tomato, indigenous corn, spinach, babari greens, and radhuni leaves throughout the field, and flax or black cumin along the edges. Cultivating these companion crops will enable a farming family to meet their needs and sell a substantial amount in the market. This entire field would then be enriched with all the elements of eco-friendly agriculture, including cover crops, crop diversity, crop rotation, multiple cropping, pest repellent crops, trap crops, nematode-resistant crops, edge crops, and support crops (like corn). After the potatoes, patol becomes the main crop, so ginger and turmeric should be planted in the patol field in the month of Baishakh, along with chili plants. Papaya trees and taro should be planted along the field edges in Falgun. By tilling the field once at the beginning of the year, a variety of crops can be grown throughout the year without further tilling.
This method not only enriches ecological farming but also saves costs for farmers by reducing expenses in several areas:
- Land Tilling: Growing three main crops in the same field annually reduces tilling expenses by twice.
- Weed Control:Mulching and crop diversification reduce the costs of weeding and herbicides.
- Pest Control: The presence of pest repellent, trap, and support crops lowers pest control costs.
- Irrigation: The cover crops reduce the need for irrigation.
Planting nematode-resistant coriander, pest repellent crops like black cumin, tulsi, onions, and garlic in the same field increases crop diversity while enabling each plant to support one another, maintaining the natural environment.
Farmers need to organize themselves for crop diversification and adopt different crop diversification plans for different areas. These plans should consider the local and national markets, and efforts should be made to reintroduce crops that were once common but are now less cultivated. Examples include: – Buckwheat, flax, mustard, sesame, foxtail millet, barley, sorghum, millet, indigenous corn, special colored sweet potatoes (rich in anthocyanins), and taro. These crops are now valuable and nutritionally rich, and their cultivation costs are relatively low.
