Assessing the Impact of Organic Mulching on Tomato Yield and Disease Resistance

Thesis Abstract

The escalating demand for sustainable agricultural practices in tomato cultivation necessitates the evaluation of non-chemical soil and crop management strategies that can enhance yield and suppress disease prevalence while maintaining environmental integrity. Organic mulching has emerged as a potential practice that may influence soil health, moisture retention, and pest/disease dynamics; however, empirical evidence specific to its effects on tomato productivity and resistance to common pathogens remains limited and regionally variable. This study aims to assess the impact of organic mulching on tomato yield and disease resistance, with specific objectives to compare yield parameters under different mulching treatments, evaluate the incidence and severity of major tomato diseases in mulched versus non-mulched plots, and analyze changes in soil health indicators attributable to mulching practices. Employing a randomized complete block design (RCBD), the research was conducted over two consecutive growing seasons at a commercial tomato farm with a total area of 600 square meters, encompassing four experimental treatments organic mulching with straw, organic mulching with composted leaves, inorganic mulch (control), and no mulch (control), each replicated three times. The study population comprised locally sourced indeterminate tomato seedlings of the 'Roma' cultivar, with 36 plots of 16 plants each (total n=576 plants). Data collection involved standard plant growth measurements (plant height, number of fruits per plant, and fruit weight), disease assessment using visual scoring for common pathogens such as Fusarium wilt and early blight, and soil analyses including organic matter content, pH, moisture levels, and microbial activity metrics, obtained through laboratory assays. Data analysis employed analysis of variance (ANOVA) to evaluate differences in yield and disease severity among treatments at a 95% confidence level, followed by Tukey's honest significant difference (HSD) test for multiple comparisons. Additionally, multiple regression analysis was performed to examine relationships between soil health indicators and plant performance, with the conceptual framework grounded in the Systems Theory of Soil and Plant Health. Disease incidence and severity data were subjected to non-parametric tests to account for ordinal scoring scales. Validity and reliability of diagnostic assessments were ensured through calibration of disease scoring criteria and standard laboratory procedures, while ethical considerations adhered to local agricultural research guidelines, including informed consent from farm owners and proper disposal of diseased plant material. Expected findings include a significant increase in tomato yield in plots treated with organic straw and composted leaf mulches compared to inorganic mulch and no-mulch controls, with reductions in disease incidence and severity attributable to mulching practices. It is hypothesized that organic mulches enhance soil microbial diversity and organic matter, thereby elevating disease suppressive mechanisms and soil moisture retention, which collectively contribute to healthier, more productive plants. The results are anticipated to demonstrate that organic mulching can serve as an effective eco-friendly strategy for improving tomato production systems, reducing reliance on chemical fungicides, and fostering sustainable agriculture. The study's contribution to existing knowledge lies in providing region-specific empirical evidence on the multifunctional benefits of organic mulching in tomato cultivation, elucidating the underlying soil-plant-pathogen interactions, and informing best management practices for growers seeking sustainable intensification methods. It also advances the theoretical understanding of soil health as a pivotal factor in crop resilience, supported by the Systems Theory model. The findings will support extension services and policymakers in promoting organic mulching as an integrated pest and soil fertility management strategy. The conclusion underscores the efficacy of organic mulching in enhancing tomato yield and resistance to major diseases, advocating for its broader adoption among smallholder and commercial farmers. Recommendations include encouraging the use of locally available organic materials for mulching, incorporating organic mulching into integrated pest management (IPM) programs, and conducting further longitudinal studies to explore long-term soil health benefits and economic feasibility. Future research should focus on elucidating microbial community shifts via metagenomic approaches and assessing economic cost-benefit ratios of mulching practices under diverse agro-ecological zones.