Effects of Municipal Solid Waste Compost Supplemented with Inorganic Nitrogen on Physicochemical Soil Characteristics, Plant Growth, Nitrate Content, and Antioxidant Activity in Spinach
2021
Rui M. A. Machado | Isabel Alves-Pereira | Miguel Robalo | Rui Ferreira
In this study, we evaluated the effects of municipal solid waste compost supplemented with inorganic N on the physicochemical properties of soil, plant growth, nitrate concentration, and antioxidant activity in spinach. Experiments were carried out in neutral and acidic soils that were low in organic matter. A fertilized soil was used as a control, while four compost treatments—two compost rates of 35 and 70 t ha<sup>−1</sup>, supplemented or not with inorganic N (92 kg N ha<sup>−1</sup> as Ca (NO<sub>3</sub>)<sub>2</sub>)—were applied by fertigation. The addition of compost increased the soil organic matter content and pH in both soils. The compost supplementation with N greatly increased the shoot dry weight and spinach fresh yield by nearly 109%. With the highest compost rate and 43% N applied, the yield increased in both soils, similar to results obtained in fertilized soil (3.8 kg m<sup>−2</sup>). The combined application of compost and N could replace inorganic P and K fertilization to a significant extent. The compost application at both rates and in both soils considerably decreased shoot Mn concentrations.
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