عنوان مقاله [English]
Rice (Oryza sativa L.) is the second most important cereal in the world after wheat. Chemical inputs including fertilizers and pesticides are applied to paddy lands to enhance yield and control pests and diseases. Although, this crop has been cultivated organically in some parts of the world. Despite a lot of research, policy and public attention, only a small portion of the total agricultural land has been dedicated to organic farming. Due to the destructive effects of conventional agriculture on the environment through the excessive use of chemical inputs, switching to sustainable agriculture is increasing day by day. One of the pillars of sustainable agriculture is the use of organic fertilizers in agro-ecosystems with the aim of eliminating the use of chemical fertilizers. Organic rice cultivation is emerging as a sustainable alternative in Mazandaran province which has numerous capabilities to transit from conventional to organic agriculture. The present study, therefore, was designed to evaluate the quantitative and quality characteristics of rice in three conventional, low-input and organic agricultural systems in Mazandaran Province.
Materials and Methods
The present study was conducted during 2015 and 2016 cropping seasons in three different regions of Mazandaran province (Babol, Fereydounkenar and Amol cities). For organic, low-input and conventional agricultural systems, three, four and six fields were selected in these cities, respectively. Selected fields had been under the same agricultural system for at least the last three years. In organic agricultural systems, standard poultry manure and biofertilizers including Azotobacter and Barvar2 were used. Also, Trichogramma bee, sex pheromones, fungicides, and biological insecticides were applied to control the common pests and diseases. Furthermore, the weeds were controlled manually. In the low-input system, minimum amounts of external inputs such as chemical fertilizers and pesticides were applied as compared to the conventional system. At the beginning of the growing season, the farmers were justified to apply all agronomic operations from the seedbed preparation to harvest in accordance with recommendations of the Rice Research Institute of Iran. Agronomic characteristics and physical quality properties including grain yield, conversion efficiency, hull percentage, head rice percentage and chemical properties including protein content, amylose percentage, and gelatinization temperature were determined. Data were subjected to analysis of variance and mean comparison by SAS 9.4 statistical software.
Results and Discussion
The results showed that in two regions of Babol and Amol, the conventional and low-input systems had more grain yield than an organic system. Among three regions, the highest grain (4978.33 kg.ha-1) and biological (8532.33 kg.ha-1) yields were obtained in the Fereydounkenar region in the low-input system. Those yields were 4.73 and 2.80 percent, and 29.99 and 29.12 percent more than the conventional and organic systems, respectively. In terms of grain quality characteristics, despite higher percentage of protein content in 2015 and 2016 (6.27 and 1.04) in conventional culture, the maximum conversion efficiency (68.05 and 69.05) and complete rice percentage (64.70), seed length after baking (13.46), the least husk percentage (22.47 and 21.86), bran (9.47 and 9.08) and broken rice (4.00 and 2.14) were recorded in organic farming system.
In conclusion, low-input sustainable farming would be more appropriate because of its greater yield and less consumption of chemical inputs, which reduces expenses while increasing sales income. In terms of the quality, particularly conversion efficiency, however, organic farming was better than the other two systems. In general, in the present conditions, it is important to consider not only the grain yield but also the yield quality. Accordingly, low-input agricultural system could be recommended to the farmers, but in the long run, the organic agricultural system will be advisable to meet both food safety and environmental health. However, the decision, in this case, requires further studies and perennial experiments.