Title: Meta-analysis of the effect of chemical and bio-fertilizers on the rice production in Iran
Author: Rahman Erfani Moghaddam
Rice (Oryza sativa L.) is an important global food crop and a main source of calories for about 60% of the world population. Fertilizers are essential components of modern agriculture and play a vital role in improving rice and other crop yields. We performed a meta-analysis to investigate the researches on the application of fertilizers on rice and to determine how different types of fertilizers including chemical (nitrogen (N), phosphorus (P), potassium (K), silicon (Si), and micro-nutrients), organic (compost and manure) and bio-fertilizers (plant growth-promoting rhizobacteria (PGPR) and fungi (PGPF)) influence on rice productivity in Iran. The results showed that research related to fertilizer application on rice from 2000 to 2018 initially increased and then decreased, and most researches were in 2011. However, research on the application of organic and biological fertilizers had been increased. Overall, less than 35% of fertilizer studies on rice were related to organic and biological fertilizers. A significantly positive overall effect of fertilizers was noted on biological yield (28.39%), grain yield (26.02%), harvest index (3.17%), and 1000-grain weight (4.86%). The chemical, organic, and bio-fertilizers positively influenced grain yield by 26.78, 15.20, and 26.61%, respectively. Among all types of fertilizers, N has the most important role in rice production and is responsible for 38% of yield. For N and P, the most increase in yield (47.60 and 20.52%, respectively) had been calculated by high fertilization rates (>120 and >80 kg h-1, respectively), while the highest rice yield was obtained from moderate K and Si fertilization rates (40-80 and 250-500 kg ha-1, respectively). Overall, it seems that lower rates of K and Si fertilizers could be used in paddy fields for reaching optimum yield. Furthermore, in order to achieve sustainable agriculture, further studies on the use of organic and biological inputs are needed.
Keywords: Biological fertilizers, Chemical fertilizers, Meta-analysis, Organic fertilizers, Rice production