Abstract
Organic fertilizers have recently been gaining popularity; however, their governance is not completely assessed in developing countries. This study investigated the nutrient composition of so-called organic fertilizers in Vietnam’s markets and issues related to their production, and evaluated their potential to contaminate the groundwater. We analyzed the physicochemical properties of 12 domestic and four imported products of the fertilizers, and conducted a cultivation experiment in sandy soil with the fertilizer applied at a rate of 200 mg N kg−1 soil using an automatic watering apparatus in a greenhouse. We further studied the production of an “organic fertilizer” from coffee by-products. The nutrient content greatly varied among domestic products, whereas they were quite similar among imported products. The product packaging of the collected samples lacked information regarding raw materials. Two thirds of the domestic products contained over 30% of the total N in the inorganic form, implying that the N content dramatically increased in the fertilizers rather than in their supposed raw materials. The stages involved in the production were composting, the addition of extra soil as a bulking agent, and the mixing-in of chemical substances to increase the nutrient content before packing. The remarkably high ratio of inorganic N to total N was attributed to excessive N leaching from soil by the application of domestic fertilizers. These results suggested the need for quality criteria guidelines for organic fertilizers in Vietnam that underline not only nutrient levels, but also the control of raw materials and production process of compost, because they are closely related to nutrient uptake and the leaching loss of nutrients.
Highlights
Organic agriculture according to the internationally accepted standards is a relatively new method of farming in developing countries
Nguyen et al [9] reported that improved land tenure security is associated with a higher level of manure use by farm households
To determine the reasons why nutrient content greatly varied among “organic fertilizers”, we investigated the flow of raw materials and manufacturing processes for an “organic fertilizer” made from coffee by-products
Summary
Organic agriculture according to the internationally accepted standards is a relatively new method of farming in developing countries. Easy labeling showing environmental performance costs much less than certifying with international agencies has probably led Vietnamese farmers to move away from international certification and opt for a cheaper labeling scheme [10] In this context, the organic fertilizer industry has recently expanded. Various fertilizers labeled as “organic fertilizer” are being sold in the markets; criteria of their raw materials and production have not been established. The objectives of this study were to clarify the nutrient composition of the so-called organic fertilizers and elucidate the effects of their application on cropping plants and the leaching loss of nutrients from agriculture land. To determine the reasons why nutrient content greatly varied among “organic fertilizers”, we investigated the flow of raw materials and manufacturing processes for an “organic fertilizer” made from coffee by-products
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