Organic Farming Improves Soil Microbial Abundance and Diversity under Greenhouse Condition: A Case Study in Shanghai (Eastern China)

Abstract

Agricultural practices have significant impacts on soil properties and microbial communities; however, little is known about their responses to open field and plastic tunnels under organic and conventional farming. We therefore investigated the responses of soil chemical variables and microbial communities to different agricultural management and cultivation types, including organic management in open field (OF), organic management in plastic tunnels (OP), conventional management in open field (CF) and conventional management in plastic tunnels (CP), by using a pyrosequencing approach of 16S rRNA gene amplicon. Both factors had significant influences on the soil properties and microbial communities. Organic farming increased the nutrient-related soil variables compared to conventional farming regardless of cultivation type, especially for the available N and P, which were increased by 137% and 711%, respectively, in OP compared to CP. Additionally, OP had the highest microbial abundance and diversity among treatments, whereas no difference was found between OF, CF and CP. Furthermore, OP possessed diverse differential bacteria which were mainly related to the organic material turnover (e.g., Roseiflexus, Planctomyces and Butyrivibrio) and plant growth promotion (e.g., Nostoc, Glycomyces and Bacillus). Redundancy analysis (RDA) showed that pH, electrical conductivity (EC), nutrient levels (e.g., available N and available P) and total Zn content were significantly correlated to the structure of the microbial community. Overall, our results showed that the long-term organic farming with high fertilizer input increased soil nutrient levels and microbial abundance and diversity under plastic-tunnel condition compared to other cultivation systems.

Potential Benefits and Risks for Soil Health Derived From the Use of Organic Amendments in Agriculture

“…In another study [107], the long-term effects of organic versus conventional fertilization on soil microbial communities were investigated, finding out that the former modulated microbial community composition while increasing microbial richness and diversity. Similarly, other authors [108] reported that organic farming promotes soil microbial diversity and the abundance of beneficial soil microorganisms, with concomitant beneficial effects on the stability of the soil ecosystem. An improvement in soil microbial structural and functional diversity, as well as an increase in bacterial richness and evenness, was reported [109] after the application of organic amendments to agricultural soil.…”

“…In addition to improving soil biological properties, organic amendments are also known to positively influence soil chemical properties. In fact, the abovementioned positive effects of organic amendments on soil microbial communities are often linked to changes in soil chemical characteristics driven by the application of amendments [45,108,120]. Several authors [121,122] evidenced the key role of soil pH for both microbial community structure and function.…”

Constructal Macroscale Thermodynamic Model of Spherical Urban Greenhouse Form with Double Thermal Envelope within Heat Currents

“…It is true that GI is currently emerging by becoming an interesting tool for cost-effective urban sustainability [8][9][10][11][12][13][14][15][16][17][18][19][20], and for this reason it is seen in the framework of the present paper as a main point of this case study in terms of innovative architectural programmatic regeneration and applied thermal engineering investigation. Additionally, as it results from Taylor Lovell's research [20] it is argued that the contemporary Occidental world employs urban agriculture as a new boundary for land use planning, architectural, and landscape design in order to follow "a sustainable urban development and transformation of the cityscape supporting community farms, allotment gardens, rooftop gardening, edible landscaping, urban forests, and other productive features of the urban environment" [20].…”

“…As a consequence, a variety of economic-environmental multifaceted reforms are applied in an international level so as to "experiment with urban and peri-urban economic bases which make the city the center of transition towards a 'low carbon' economy" [1]. Since the early 1970s, the first petrol crisis of 1973, architecture-and the building sector in general-became a target of environmental reform [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]. This reform resulted in segregating disciplines and creating antagonist relations.…”

“…The main idea of the present paper is to support the need of refurbishing the urban context through the integration of urban agriculture elements within the thermodynamic architectural design while developing a scientific methodology that assists the artistic dimension of the architecture that consists of creating forms to accompany life. Past research clearly showed that urban agriculture projects reside on a global strategy for greening cities to regulate urban temperature and to improve microclimates, while having a thermodynamic potential increase food production and waste recycling [8][9][10][11][12][13][14][15][16][17][18][19][20].…”