Comparative Analysis of Soil Fertility in Conventional and Organic Farming Systems

Thesis Abstract

Soil fertility is a critical determinant of agricultural productivity and sustainability, yet limited comparative data exist regarding the influence of conventional versus organic farming systems on soil health in temperate agroecosystems. This study aims to systematically evaluate and compare soil fertility parameters under these two distinct agricultural practices, with the specific objectives to (1) quantify and contrast physicochemical soil properties—including pH, organic carbon, total nitrogen, available phosphorus, exchangeable cations, and soil texture—between conventional and organic plots; (2) assess microbial biomass and activity as biological indicators of soil fertility using phospholipid fatty acid (PLFA) analysis and dehydrogenase enzyme activity; (3) identify key soil management factors influencing fertility metrics via multiple regression analysis; and (4) develop a comprehensive model elucidating the relationships among soil properties, biological activity, and farming practices. Utilizing a cross-sectional comparative research design, the study was carried out in two agricultural districts characterized by extensive wheat and vegetable farming. The population comprised farmers practicing conventional and organic systems for a minimum of five years. A stratified random sampling technique selected a total of 60 farms—30 conventional and 30 organic—ensuring representativeness and comparability. Soil samples were collected at 0-20 cm depth from each farm’s main cultivated plots, with laboratory analyses conducted in accordance with standard protocols physicochemical parameters measured through inductively coupled plasma optical emission spectrometry (ICP-OES) for mineral contents, pH determined via glass electrode, and organic carbon via Walkley-Black method. Biological activity was assessed by quantifying microbial biomass carbon using fumigation-extraction, and enzyme activities via spectrophotometric methods. Data were subjected to descriptive statistics to summarize the soil properties. Differences between the two farming systems were statistically evaluated through analysis of variance (ANOVA) at a significance level of p<0.05. The relationships among variables were explored using multiple regression models, while principal component analysis (PCA) helped identify key factors influencing soil fertility. The study also employed the Theory of Planned Behavior to interpret farmers' management decisions regarding soil practices. It is anticipated that organic systems will exhibit significantly higher levels of organic carbon, microbial biomass, and enzymatic activity, indicative of enhanced biological soil health, whereas conventional soils may display higher mineralization rates but potentially lower biological activity. The findings are expected to contribute novel insights into the specific soil fertility dynamics associated with contrasting farming methodologies, filling critical gaps identified in prior literature that often focus narrowly on either physicochemical or biological parameters without integrated assessments. The study’s integrated model will provide a mechanistic understanding of how management practices influence soil health components, with practical implications for sustainable agriculture policy and practice. The main conclusion will emphasize that organic farming systems generally promote superior biological soil health and organic matter stability, which are crucial for long-term productivity and environmental health. Based on these insights, the study recommends adoption of integrated soil management practices that emphasize organic amendments and biological enhancement, alongside policy frameworks incentivizing organic methods. Future research avenues include longitudinal studies to examine temporal variability and the extension of such comparative analyses to different cropping systems and agro-ecological zones, thereby broadening the applicability of the findings to enhance sustainable land management globally.