While peat resources to produce organic fertilizer are declining, the utilization of agricultural waste products to produce organic fertilizer, improve soil fertility, increase productivity and reduce greenhouse gas emissions has been considered as an important and realizable aim for agricultural production in Vietnam.
According to the Department of Cultivation of the Ministry of Agriculture and Rural Development, current demand for using organic fertilizer in Vietnam stands at around 13 million tonnes per year, whereas domestic production capacity stands at just 500,000 tonnes.
"There are about 150 companies specializing in producing organic fertilizer, whereas there are some large scale companies, such as Gianh River, Que Lam and Thien Sinh. The remainder is small companies with capacity of just 500-2,000 tonnes per year," Cao Viet Hung from the Department of Land Use and Fertilizer said.
In a total of 21 categories of fertilizer issued by the Ministry of Agriculture and Rural Development, the total number of organic fertilizer reached over 1,500. Although demand for using organic fertilizer is increasing, peat resources are declining in both quality and quantity. Vietnam's current peat resources have 12-15 percent of content of organic substance. Thus, the production of organic fertilizer is difficult.
Fertilizer quality test results reveal that 25-35 percent of tested samples lack high quality organic content. Therefore, the material exploitation from agricultural waste products is considered a valid alternative, as it provides new sources of fertilizer and contributes to reducing carbon emissions from the burning of straw.
To produce 13 million tonnes of organic fertilizer containing 15-22 percent of organic content, 2-3 million tonnes of pure organic substance is required. According to the last year's figures, Vietnam produced about 42 million tonnes of rice, 4.6 million tonnes of corn, 10 million tonnes of cassava and 1.1 million tonnes of coffee. Therefore, 50 million tonnes of waste products from these major crops can be exploited. If handled in accordance with the regulations and the production process, the production of 13 million tonnes of organic fertilizer is quite feasible.
Department of Livestock of the Ministry of Agriculture and Rural Development master Nguyen Quynh Hoa said that the greenhouse gas emissions in livestock is equivalent to 11.15 million tonnes of CO2 each year, accounting for 17.2 percent of its total in agriculture. Therefore, the use of waste products from biogas to produce organic fertilizer is another key solution.
The waste products from biogas have three parts containing soluble nutrients and trace elements. A tonne of discharged water is equivalent to about 0.8-1.7kg of urea, 0.5-1.5kg of super phosphate and 0.5-0.9kg of potassium. In particular, discharged waster is a fast-acting fertilizer containing soluble nutrients. Therefore, it is easy for crops to absorb these nutrients when irrigating. Moreover, residue with organic compounds and other substances helps crops to absorb more nutritious elements.
"The waste products from biogas have recently had many applications in agricultural production. In particular for soil improvement, the waste products from biogas help to improve land cultivation, soil structure and physical properties," Hoa said.
According to the Soils and Fertilizers Research Institute (SFRI), the use of 60cu.m of discharged water and pure water to fertilize one hectare of cabbage will increase productivity by 24 percent. After a growing season, with each hectare, farmers can save over 60kg of urea nitrogen and 65kg of super phosphate. The use of discharged water for irrigation also helps to reduce the number of pesticide sprays.
In addition, the use of waste products from biogas for fish breeding is also a positive target because it contributes to the reduction of fish diseases and CO2 emissions into the environment.
According to experts, agricultural gas emissions are continuing to rise. In particular, emissions from livestock would exceed emissions from the agricultural land in the 2020-2030 period, amounting to 30 percent of greenhouse gas emissions in agriculture. Therefore, in addition to speeding up progress of planning livestock areas in association with environmental protection, the authorities need to rapidly promote a biogas program for the livestock industry in order to reduce gas emissions and bring higher economic advantages in agricultural production./.
