Abstract
Currently, the majority of paddy fields in Japan are grown using chemical fertilizers and synthetic chemical pesticides, since chemical fertilizers can provide the nutrients necessary for plant growth. However, there are concerns regarding the environmental impact of chemical fertilizer and pesticides production, such as reduction of soil microorganisms and water pollution due to the runoff of fertilizer components from the soil caused by excessive fertilizer application. In this study, we investigated the effects of the application of organic and chemical fertilizers on the plant growth of paddy fields, in addition to their effects on the chemical and biological properties of the soil. The panicle numbers of rough and brown rice, the 1000-grain weight of the rough and brown rice, and the percentages of ripened grains were significantly higher in paddy soils grown with organic fertilizers than in those grown with chemical fertilizers. In addition, the total carbon (TC) contents and pH values were significantly higher in the soils of paddy fields grown with organic fertilizers. Furthermore, the soils of paddy fields grown with organic fertilizers exhibited greater bacterial biomasses, N circulation activity, and P circulation activity than the soils of paddy fields grown using chemical fertilizers, although the differences were not significant. In this study, the difference in plant growth was appeared in fertilizer application such as organic and chemical fertilizers. It was indicated that the organic fertilizer and pesticide reduction management increased the soil bacterial biomass and activated the material cycle such as N circulation activity.
Highlights
Rice is grown in various parts of the world between latitudes of 50 ̊ north and 35 ̊ south [1]
The paddy soils cultivated with organic fertilizers have higher N and P circulation activities in February, May, August, and November than when chemical fertilizers were employed, thereby indicating active material cycles
Paddy soil cultivated with organic fertilizer was classified as Group 1 in March, May, August, and November, while paddy soil cultivated with chemical fertilizers belonged to Group 3 in March, May, August, and November
Summary
Rice is grown in various parts of the world between latitudes of 50 ̊ north and 35 ̊ south [1]. Asia accounts for ~90% of worldwide rice production, outside of Asia, rice is grown in Brazil and Colombia (South America), and in Egypt, Senegal, and Madagascar (Africa). Since chemical fertilizers do not contribute to the biotic and physical properties of the soil, or enhance soil fertility, soil degradation is likely to occur in agricultural practices that use only chemical fertilizers for long periods of time. This in turn can lead to poor crop growth
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