Assessing the Impact of Organic Mulching on Soil Health and Tomato Yield

Thesis Abstract

The sustainable intensification of tomato production requires innovative practices that enhance soil health while maximizing yield, particularly within smallholder farming systems facing soil degradation and limited resource inputs. Despite the widespread acknowledgment of organic mulching as a potential agronomic practice to improve soil properties and crop productivity, empirical evidence specific to its impact on soil health parameters and tomato yield remains limited and context-dependent. Addressing this gap, the present study aims to assess the effects of organic mulching on soil nutrient status, microbial activity, moisture retention, and overall tomato yield within a representative farming zone. The specific objectives are to quantify changes in soil chemical and biological properties under different mulch treatments, evaluate the effects of organic mulch on tomato growth and yield attributes, and identify optimal mulch application regimes for sustainable tomato production. Employing a randomized complete block design (RCBD), the study was conducted over two growing seasons on a sample population of 60 smallholder farmers cultivating tomato in the region. The farmers were randomly assigned to three treatment groups control (no mulch), mulch with rice straw, and mulch with composted farm manure, each with twenty replicates. Data collection involved both laboratory analyses and in-field measurements soil samples were analyzed for key chemical indicators including pH, organic carbon, nitrogen, phosphorus, and potassium using standard soil testing procedures; microbial biomass and activity were assessed via phospholipid fatty acid (PLFA) analysis and dehydrogenase enzyme activity assays; soil moisture retention was monitored through gravimetric methods; and plant growth parameters and yields were recorded at harvest. The validity and reliability of the soil and crop data collection instruments were ensured through calibration against certified standards and repeated measurements. Analytical techniques included Analysis of Variance (ANOVA) for soil and crop data, followed by Tukey’s post hoc tests to determine significant differences among treatments. Additionally, multiple regression analysis was employed to explore relationships between soil health indicators and tomato yield outcomes, grounded in the principles of the Soil Quality Index framework. Key findings are anticipated to demonstrate that organic mulching significantly enhances soil organic carbon, microbial activity, and moisture retention compared to control plots, with rice straw mulch potentially outperforming composted manure in certain soil parameters. These improvements are expected to correlate positively with increased plant vegetative growth, fruit size, and overall yield, confirming the hypothesis that soil health improvements translate into enhanced productivity. The study is also expected to reveal optimal mulch application rates that sustain soil fertility and maximize yield without incurring additional costs, thereby offering practical guidelines to smallholder farmers. This research contributes novel empirical data to the field of sustainable agriculture, particularly within commodity-specific contexts like tomato cultivation. By integrating soil biological, chemical, and physical indicators into a comprehensive assessment, it advances understanding of the mechanisms whereby organic mulching influences soil resilience and crop performance. Theoretically, the study supports the application of the Soil Quality Index and the Biological Control Theory to explicate the pathways of soil health improvement via organic amendments. Its findings provide actionable insights for policymakers, extension services, and farmers aiming to adopt environmentally friendly, cost-effective practices aligned with climate-smart agriculture principles. The main conclusion underscores that organic mulching, especially using locally available organic residues such as rice straw, offers a viable strategy for improving soil health and increasing tomato yield sustainably. The research recommends promoting organic mulching in smallholder systems, optimizing mulch quantities based on crop requirements and resource availability, and further investigating long-term effects on soil degradation reversal. Future studies should explore the integration of organic mulching with other conservation agriculture practices and extend the assessment to environmental impacts such as soil carbon sequestration and pest suppression, thereby enriching the body of knowledge on sustainable tomato production systems.