Guar, jantar, wheat straw, and rice hull composts as replacements for peat in muskmelon transplant production

Purpose The demand for soilless media for vegetabletransplant production is increasing. Economic constraintspaired with concerns over the sustainability of peatmining have necessitated the replacement of peat withrenewable and regionally abundant alternatives. The aim ofthis study was to develop from composts complete orpartial substitutes for peat.Methods Composted guar (Cyamopsis tetragonoloba),jantar (Sesbania aculeata), wheat (Triticum aestivum)straw, and rice (Oryza sativa) hulls adjusted to 10% airfilledporosity (AFP) were blended on a volumetric basiswith peat moss at discrete levels (0–50%). Total waterholdingcapacity, shrinkage, dry and wet bulk density, pH,electrical conductivity, N, P, K, FE, B, and Zn concentrationsof each compost, their blends, and a peat control weremeasured. The experimental media were used to growmuskmelon (Cucumis melo) plants in a greenhouse. Seedgermination, shoot fresh weight, shoot height, leaf area,stem diameter, root length, and mineral nutrient concentrationsof transplants were quantified. After transplantingin the field, the growth rates and yields were measured.Nonparametric regression was used to analyze the data.Results The physiochemical parameters measured for mostof the experimental media fell within the recommendedrange for growing media; however, pH for all mediaexceeded the recommended range. Media-containing guarand jantar composts generally contained more nutrientsthan media-containing rice hull or wheat straw composts.Fresh weight, height, and root length were generallygreater for seedlings grown in media-containing rice hullcompost than for those grown in media-containing othercomposts. Seedlings grown in media-containing guar orjantar composts generally had greater tissue nutrientconcentrations.Conclusions All blends produced acceptable seedlings;however, the largest seedlings, and greatest post-transplantgrowth rate and yield were produced in media containing30–50% rice hull compost.