Municipal Waste and Poultry Manure Compost Affect Biomass Production, Nitrate Reductase Activity and Heavy Metals in Tomato Plants

Abstract

Organic wastes can be usefully recovered to produce organic amendments, for example, compost, to be used for crop production, thus reducing impacts through efficient waste management. The aim of this work was to study the effects of compost obtained from municipal waste in combination with poultry manure on plant growth, nitrate reductase (NR) activity and absorption and distribution of heavy metals (HM) in plant tissues of tomatoes, grown in pots in greenhouses. Two compost types obtained from municipal waste mixed with poultry manure (C1 = 3:2 and C2 = 2:3) were used at two different ages (105 d and 173 d) and at two mix rates with soil (32.5 g pot⁻¹ and 65 g pot⁻¹); soil with no compost amendment was used as control. The experiment was conducted using tomato plants in pots and plant growth and nutrient plant uptake was determined after 65 days from plant transplanting. Results obtained indicated that compost type and compost rate affected biomass production. However, compost age did not influence the development of plants. Nutrient status of tomato plants was also investigated with reference to the N cycle. Nitrite accumulation in the leaves increased with the increase in compost doses. The accumulation of NO₂⁻ was associated with a significant increase in NR activity. HM content in leaves decreased with compost use. HM accumulated preferentially in roots and leaves and the soil to root metals transfer was in this order: Fe (1.08–2.14)> Co (0.53–4.10)>Cu (0.28–2.28) >Mn (0.3–1.34) >Zn (0.87–1.21)>Cr (0.12–1.64). The highest and lowest dynamic bioaccumulation factors (BAF_dyn) were observed in roots and stems, respectively. The root system acted as a barrier for Cd and Pb. It was concluded that compost use is beneficial for tomato plants, with particular reference to the compost obtained by using a higher amount of poultry manure (C2) in the mix.