Turning cashew leaves into organic fertilizer

Utilizing plant residues, Binh Phuoc cashew farmers use agricultural mulch to compost rotting cashew leaves as manure, improving organic humus, increasing soil fertility...

Agricultural mulch helps to increase productivity and income for cashew growers. Photo: Tran Trung.

Double benefits

As the province with the largest cashew acreage in the country and once considered a local poverty alleviation tree, in order to increase the orchards' productivity, in recent years, people here have applied science and technology into production. In which, the application of agricultural mulch to compost rotting cashew leaves as fertilizer, improving organic humus, increasing soil fertility ... are effective solutions.

Visiting the over 10-year-old cashew garden of Mr. Vu Van Tan's family in Phu Trung commune, Phu Rieng district, we were surprised at the cashew trees thanks to sufficient nutrition, the trunk and roots are very large, the foliage is wide and thick, and the leaves are less susceptible to pests and diseases, the ground is porous without grass.

Mr. Tan said, his family has 5.5 hectares of cashew, through research found that the application of agricultural mulch brings many benefits, in 2013 he started to experiment, only the first crop yielded positive results. Accordingly, instead of burning as before, which both affects the environment and hardens the soil due to exposure to high temperatures, now with the application of agricultural mulch, all plant residues in the fields have been turned into fertilizers, with healthy cashew trees, good resistance to pests and diseases, productivity increases from 2 to 3 quintals each year.

"When the cashew leaves fell simultaneously, my family raked in long beds covered with Trichoderma and lime powder to quickly rot the leaves and grass. The cashew tree's roots just float on the ground, enough nutrients to raise healthy trees. The type of agricultural mulch also keeps the soil moist and prevents it from being washed out. As a result, the soil is very porous, rich in nutrients and reduces investment costs, especially in the season, thanks to the clean yard, the cashews fall down to where it is exposed on the ground, it is not mixed with other leaves to avoid loss," Mr. Tan shared.

Seeing the effectiveness of this model, the agricultural-service cooperative of Binh Thang commune, one of the largest cashew-growing and farming cooperatives in Bu Gia Map district, also deployed it for members to apply in production.

Mr. Ho Ngoc Anh - Chairman of Farmers' Association, Director of Binh Thang Commune Agricultural - Service Cooperative said that Binh Thang has 2,391 hectares of cashew. The whole commune has 190 farmer members who have joined agricultural and service cooperatives. Most are farmers who produce cashews according to the organic process combined with agricultural mulch, both reducing fertilizer costs and helping to achieve high yield and quality, selling at a higher price.

"Thanks to the clean process, some cashew processing, import and export companies in the area have invited foreign partners to visit and survey directly at the farms, to sign regular purchase contracts," said Mr. Anh.

Encouraging the model

Similarly, in Bu Dang district, the locality with the largest cashew growing area in the province with nearly 60,000 hectares. To widely disseminate the method, the Agricultural Service Center of Bu Dang district has built 29 models in communes and towns; organized seminars, training, and propagating the benefits for union officials and farmers at grassroots level. Each model is built on an area of 1 ha, with a cost of 4.6 million VND, of which the State supports 1,675 million VND, farmers implement counterpart model for the remaining amount. The method is simple, convenient, low cost, non-toxic. Coating film is widely sold in the market at low cost.

Agricultural engineer Tran Minh Hieu, Deputy Director of the Agricultural Service Center of Bu Dang district said: In recent years, cashew growers often clear the fields before harvesting by spraying weeds, spreading weeds, and even burning leaves. Spraying herbicides is both costly and harmful to the environment and human health. Meanwhile, using agricultural mulch has many benefits, such as utilizing plant residues for organic fertilizers, improving soil fertility, creating a favorable environment for beneficial microorganisms to grow, regulating temperature, keeping the soil moist, not washed away, preventing weeds, harmful insects, and helping plants grow well.

Ms. Le Thi Anh Tuyet, Deputy Director of Binh Phuoc Department of Agriculture and Rural Development, said that agricultural mulch has been used for in the past, especially for gardeners who grow and trade in clean vegetables, tubers and fruits because it brings multiple benefits. However, use of mulch to compost cashew leaves as organic fertilizer has not utilized because most people are afraid, maintaining the habit of burning leaves and spraying weeds, so they cannot take advantage of the superiority of this method.

“In the past, the agricultural sector of the province has always encouraged and promoted people to be creative in farming, and to enhance soil improvement with biological and organic products instead of chemical drugs. With Binh Phuoc being the cashew capital of the country, the agricultural economy accounts for a high proportion, use of agricultural mulch in cashew orchards is a method to be replicated, contributing to the development of sustainable cashew trees," said Ms. Le Thi. Anh Tuyet.