Economic problems caused by increased consumption of fertilizers from one hand and environmental issues related to non-scientific consumption of such fertilizers (e.g., pollution of water and soil, loss of soil fertility, and crop quality) on the other hand, have shifted attentions towards application of biological fertilizers. In order to reduce environmental pollution and ecological damage caused by the use of chemical fertilizers, there is a need to use resources and inputs, which not only meet crop nutrient requirements, but also guarantee the long-term sustainability of agricultural systems. The purpose of this study was to reduce the harmful effects of chemical fertilizers on the agroecosystem and to reduce the cost associated with crop production through application of biofertilizers (free-living nitrogen-fixating bacteria, and potassium and phosphate solubilizing bacteria) on mung bean.
Material and methods:
A field experiment was carried out as a randomized complete block design with factorial arrangement of treatments. Two mung bean genotypes (Dezfouli and Indian) were planted under six fertilization systems at the Agricultural Research Station of Ferdowsi University of Mashhad, Iran in 2017. Fertilization treatments were Nitro Bacteria (NB), Phosphate Power Bacteria (PhPB), Potassium Power Bacteria (PPB), NB+PhPB+PPB, chemical nitrogen fertilizer (N), and no fertilizer as control (C). Prior to planting, the soil was sampled at a depth of 0-30 cm for measurement of common physico-chemical characteristics. At the end of the growing season, an area of 1 m2 from the middle of each plot was harvested for crop traits. Plant height, the number of branches per plant, grain yield, biological yield, and yield components including the number of pods per plant, the number of seeds per pod, and 100-seed weight were measured accordingly.
Results and discussion:
The results showed a significant difference between mung bean genotypes and also fertilization treatments regarding yield and yield components (p < 0.05). The highest biological yield (6555 kg ha-1 ) and grain yield (1558 kg ha-1 ) were obtained from Dezfouli genotype under NPB+PhPB+PPB treatment. The lowest biomass and grain yield were observed for Indian genotype under control treatment with 3518 and 1393 kg ha-1 , respectively. The results showed that the combined application of nitrogen stabilizing bacteria and potassium and phosphate release bacteria, due to increased access to nutrients that is an effective factor in stimulating the growth and photosynthesis of plants, improved conditions for growth and production of photosynthetic materials, and also increased the yield of mung bean plants.
It was revealed that the combined application of various biofertilizers not only improves the mung bean yield, but also can reduce negative aspects of chemical fertilizer application in crop production systems. Paying attention to more frequent use of biological fertilizers could be considered as an important agroecological approach, which results in healthier soil and water resources.