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Radu Lăcătuşu, Romeo Căpăţână and Anca-Rovena Lăcătuşu

Abstract

The soil fertilization in ecological agriculture is done mostly using organic fertilizers. Some of them are prepared as compost from waste, but other haven’t, until now, any recycling possibility. In this context, for the preparation of new types of compost, we used three type of waste: sewage sludge from waste water treatment, marine algae and farmyard manure. We have made four different composting variants, each consisting of different proportions of the three waste: equal parts (33.33%) of each waste, 50% of each of the three wastes separately, the difference being made up in equal amounts (25%) of the other two wastes. Composting process was performed in Könemann silos (cubs with side by 1.20m) and lasted 60 days, from July 19 until September 16, when the composted material has passed the stages of reduction and oxidation. During composting process, in the reductive stage the material has reached a temperature up to 63°C Celsius, enough heat for its sterilization. Initial material, semi composted and final composted material were been chemical analyzed, especially in terms of macro- and microelements, analytical results revealing high and normal content of such chemicals. Therefore the achieved compost could be used in organic farming systems.

Open access

Radu Lacatusu, Anca-Rovena Lacatusu, Mihaela Lungu, Mihaela Monica Stanciu Burileanu and Andrei Vrînceanu

Abstract

The sewage sludge from wastewater treatment plant of Iasi, a city with 300,000 inhabitants, for domestic and industrial origin, was stored in a mud pond arranged on an area of 18,920 m2. Chemical analyzes of the sludge showed that, of all the chemical elements determined, only Zn is found at pollutant level (5739 mg∙kg-1), i.e. almost 30 times more than the maximum allowable limit for Zn in soil and 45 times more than the Zn content of the soil on which the mud pond has been set. Over time, the content of Zn in the mud pond, but also from soil to which it has been placed, has become upper the normal content of the surrounding soil up to a depth of 260 cm. On the other hand, the vegetation installed on sewage sludge in the process of mineralization, composed predominantly of Phragmites, Rumex, Chenopodium, and Aster species had accumulated in roots, stems and leaves Zn quantities equivalent to 1463 mg Kg-1, 3988 mg Kg-1, 1463 mg Kg-1, respectively, 1120 mg∙Kg-1. The plants in question represents the natural means of phytoremediation, and sewage sludge as such may constitute a fertilizer material for soils in the area, on which Zn deficiency in maize has been recorded. In addition, the ash resulted from the incineration of plants loaded with zinc may constitute, in its turn, a good material for fertilizing of the soils that are deficient in zinc.

Open access

Radu Lăcătușu, Anca-Rovena Lăcătușu, Romeo Căpățână, Mihaela Lungu, Rodica Lazăr and Irina Ramona Moraru

Abstract

Aiming to increase the use of natural resources and unexplored opportunities in industrial and agricultural practices, the marine algae biomass, that causes serious environmental problems in the Romanian Black Sea coast, was used in association with another two organic wastes, farmyard manure from cattle-breeding farms and sewage sludge resulted from the waste water treatment, to produce a compost suitable as organic fertilizer for plant cultivation in ecologic farming systems. Four variants of compost, first representing equal parts (33.33%) of those three components, and the other three proportions of 50% of each component, the difference being ensured in a ratio of 25% of each of the other two components, have been tested in a field experiment to assess their effects, both on the agro-chemical properties of the soil and on the sunflower plants development and crops. Until the phase of sunflower calathidia formation, the compost containing 50% farmyard manure influenced the best plant development in terms of height and number of leaves, then, at the end of vegetation period, the best plant development took place under the influence of compost prevalent in marine algae. The mobile forms of N and P were statistically differentiated depending on the dose of compost, the maximum dose generating the lowest content levels in the soil, as a result of higher absorption of these chemical elements in plants. The content of P and Ca in sunflower leaves recorded significant differences.