Shredded Paper as Soil Enhancer in the Growth of Mustard (Brassica Rapa Subsp. Oleifera) and Pechay (Brassica Rapa)

Abstract

The escalating global reliance on synthetic fertilizers has precipitated critical soil degradation, characterized by increased acidification and nutrient leaching that leads to environmental issues like aquatic eutrophication. This study addresses the urgent need for sustainable soil restoration by investigating the efficacy of composted shredded paper as a low-cost, cellulosic soil amendment to enhance the growth performance of Brassica rapa (Pechay) and Brassica rapa subsp. oleifera (Mustard). Utilizing a randomized experimental design in a controlled greenhouse environment, the research evaluated three amendment concentrations (10:1, 10:2, and 10:3) against an unamended control. Systematic assessments were conducted over a 30-day duration to quantify changes in hydro-physical properties, chemical pH shifts, biomass accumulation, and potential nitrate toxicity. The findings reveal that shredded paper amendments significantly optimize soil physical architecture, most notably reducing water infiltration time from a baseline of 24.67 seconds to 3.33 seconds in the 10:3 treatment group. Chemically, the amendment served as an effective buffering agent, mitigating soil acidity by elevating pH levels from an acidic 5.5 to a more neutral 6.2. While germination rates remained consistent across all variables, Brassica rapa exhibited peak vegetative vigor at the 10:2 ratio, showing marked increases in shoot length and total biomass. Critically, nitrate levels remained well below the 2000 mg/kg toxicity threshold, confirming the safety of the produce for human consumption. These results demonstrate that upcycling paper waste not only improves soil hydraulic conductivity and fertility but also offers a scalable strategy for carbon sequestration and waste management in urban and school-based agricultural systems.