Recycling Agricultural Wastes and By-products in Organic Farming: Biofertilizer Production, Yield Performance and Carbon Footprint Analysis

Abstract

The Circular Economy concept implies the re-design of existing production systems in agriculture, by promoting agricultural waste recycling. In an organic zucchini—lettuce rotation, two different agroecological tools were considered: biofertilizer and presence or absence of green manure (GM+ and GM−). In particular, we compared: (i) anaerobic digestate from cattle manure, co-composted with vegetable wastes, with the presence of GM (AD GM+); (ii) olive pomace compost, re-composted, with the presence of GM (OWC GM+); (iii) municipal waste compost with GM (MWC GM+); (iv) municipal waste compost without GM (MWC GM−). These materials were tested with a commercial organic fertilizer without GM (COF GM−) as a positive control. The objectives were: (i) assessing the environmental sustainability of biofertilizers through carbon footprint analysis by greenhouse gas—GHG—emissions; (ii) evaluating the agronomic performance on the vegetable rotation, by energy output assessment. The total carbon emissions of biofertilizers production was 63.9 and 67.0 kg of CO2 eq Mg−1 for AD and OWC, respectively. The co-composting and re-composting processes emitted 31.4 and 8.4 kg CO2 per Mg of compost, respectively. In AD the ventilation phase of composting accounted for 37.2% of total emissions. The total CO2 emission values for the two-crop cycles were the highest in COF GM− and the lowest in OWC GM+, due to different fertilizer sources. On the average of the treatments, the input that induced the highest CO2 emission was irrigation (37.9%). The energy output assessment for zucchini and lettuce highlighted similar performance for all the treatments. Our findings demonstrated the validity of the tested processes to recycle agro-industrial wastes, and the potential of agroecological practices (GM) to mitigate GHG emissions.

Unveiling the Efficiency of Vermicompost Derived from Different Biowastes on Wheat (Triticum aestivum L.) Plant Growth and Soil Health

“…Globally, total organic solid wastes produced from livestock, human, and crop activities are more than 38 billion m 3 [6]. Rice straw produced in bulk quantity and poor feed for animals having higher silica and lingo-cellulose contents; is rather difficult to manage or dispose of [7].…”

Organic Vegetable Crops Managed with Agro-Ecological Practices: Environmental Sustainability Assessment by DEXi-met Decision Support System

“…Sci. 2019, 9, 4148 2 of 15 of agro-ecological service crops (ASC; [4]), utilization of soil amendments [5], and crop/livestock mixing can increase agro-ecosystem diversity and complexity both over space and time [6].A prerequisite to the systems sustainability implementation is the development, improvement, and/or choice of the best possible assessment methods. In fact, there is a need to determine the reliability of innovative management practices with respect to the conventional ones, and to clarify the benefits and the drawbacks of the full or partial application of an agro-ecological approach.…”

“…Sci. 2019, 9, 4148 2 of 15 of agro-ecological service crops (ASC; [4]), utilization of soil amendments [5], and crop/livestock mixing can increase agro-ecosystem diversity and complexity both over space and time [6].…”

Sustainability Assessment of the Green Compost Production Chain from Agricultural Waste: A Case Study in Southern Italy

“…Referring only to global warming, in our experimental conditions the production of 1 ton of LC caused an emission of 250 kg of CO 2 eq; while the production of 1 ton of HC caused an emission of 199 kg of CO 2 eq. Diacono et al 2019 [70], using anaerobic digestate from cattle manure, reported a cumulative emission of about 31.4 kg CO 2 eq ton −1 under an aerated composting process. This value is lower if compared to ours due mostly to the raw materials used in the different studies (particularly, low dry matter content of green waste utilized in this study).…”