Effects of long-term application of organic and chemical fertilizer on composition of soil microorganisms and yields of sweet corn

Abstract

The long-term organic farming experiment on KDARES (Kaohsiung District Agriculture Research Extension Station) were initiated in 1988 The original goal of this experiment was focused on comparison with soil properties and crop yield between two rotation systems (R1 and R2 were based on different crops combination Since 2004 R1: paddy upland rotation; R2: upland rotation) and among three fertilization methods (OF: Organic fertilizer IF: Integrated fertilizer CF: Chemical fertilizer) In this study effects of different fertilization treatment with rotation systems on microorganisms and yield trends of sweet corn were analyzed Firstly diverse soil microbial community is determinant for sustainable agriculture Rich microbial diversity has presumably improved soil health for economic crops to grow In this part the benefits of paddy-upland rotation on soil microbial diversity and specific microbes are thus intensively explored The microbiome from multiple factor experiment (three fertilizations coupled with two rotation systems) were investigated by novel enrichment and co-occurrence analysis in our experimental field which well maintained for 25 years Using next-generation sequencing technique we firstly present explicit evidence that different rotation systems rather than fertilizations mightily governed the soil microbiome Paddy-upland rotation (R1) obviously increase more microbial diversity than upland rotation (R2) whether organic (OF) chemical (CF) or integrated fertilizers (IF) were concomitantly applied Besides the specific bacterial composition dominated in OF soil is more similar to that of R1 than to CF suggesting that paddy-upland rotation might be the best option for sustainable agriculture if chemical fertilizer is still required Interestingly the pot bioassay verified clearly the novel analysis prediction illustrating that greater microbial diversity and specific microbial composition correlated significantly with disease resistance This finding highlights the eminence of paddy-upland rotation in promoting microbial diversity and specific microbial compositions preserving soil health for sustainable agriculture Finally climate change affects global crop production in the past decade Exploring the impact of different fertilization methods on crop yield stability has become an extremely important topic in sustainable agriculture In this part the objective is to explore the effects of various fertilization regimes with climate variability on yield stability for sweet corn production in southern Taiwan In the same experimental field we investigated the yields of sweet corn from 2009 to 2018 We found that different fertilization changed the marketable yields of fresh fruit (ear) which slightly increased for organic fertilizer but substantially decreased for both chemical (p = 0 0001) and integrated (p = 0 0061) fertilizer Thus based on these 10 years of observation yields among fertilization treatments were analyzed with weather and soil parameters to determine the possible factors involved Both multiple linear regression equation (p < 0 0001 adj R2 > 0 57) and regression tree analysis illustrated significantly negative correlations between average ear weight and relative humidity under the chemical fertilizer treatment In this study we show for the first time that chemical fertilizer had the lowest yield resilience in response to regional relative humidity change compared to organic and integrated fertilizers Therefore comparing to conventional cultivation and organic farming the chemical fertilizer is the worst choice for sustainable agriculture

Date of Award	2020
Original language	English
Supervisor	Wen-Chi Chang (Supervisor)