Document Type : Research Paper
Authors
1
Scientific Staff, Soil Chemistry, Fertility and Plant Nutrition Research Department, Soil and Water Research Institute (SWRI)
2
Scientific Staff, Soil Chemistry, Fertility and Plant Nutrition Research Department, Soil and Water Research Institute (SWRI);
Abstract
Analysis of the trends of the cultivated area, agricultural production, and water resources in the past 50 years shows that focus of agricultural development has to be on intensification to cope with the rising demands for food of the growing population in Iran. This means more pressure on soil resources, which threatens sustainable production and food security. It also shows the key role of soil fertility and balanced soil fertilization, which is the main concern of the agricultural sector as well. In this paper, fertilizer recommendation and forecast are investigated as the first and the main steps of fertilizer system including recommendation, forecast, supply, allocation and consumption. Considering soil and plant nutrient criteria and fertility evaluation of some 20,000 soil samples revealed that more than 50 percent of the cultivated soils suffer from the deficiencies of one or more nutrients. Furthermore, the low soil organic matter content is the main limitation factor of sustainable soil fertility and production. Among the four fertilizer recommendation approaches based on soil test, fertilizer recommendation in Iran is more based on the sufficiency range approach. Due to the lack of adequate data, the other approaches including build up, maintenance, and cation balance methods have been ignored, but should be considered in the future. Fertilizer recommendation trend shows a transition from the general and regional recommendation towards the soil test recommendation along with more attention to research and soil analysis. In addition to soil test as a base of fertilizer recommendations, other factors such as climate (drought, temperature), soil (salinity), plant (uptake efficiency) and agronomic management (rotation) should be considered in the fertilizer recommendations system. Fortunately, the first steps for integration of these factors are gathered in automated fertilizer recommendation program which needs more complete investigations. Among the five main fertilizers forecasting models in Iran, fertilizer estimation is more based on crop based model and has a generation trend due to more availability of soil and plant analysis data. This trend shows more fertilizer requirement in the future. However, it is necessary to distinguish between the total fertilizer requirement and its consumption at the farm. This means fertilizers consumption is not balanced in general, while balanced fertilization should be the main policy. There should be a national soil testing program in a way to include all stakeholders (private soil test lab, producers, etc) in fertilizer program. With the preparation of soil test infrastructure and facilitation of farmers' access to soil lab and appropriate fertilizer, balanced fertilization and, consequently, sustainable soil fertility, food security, and environmental protection could be achieved.
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