Using Digestate and Biochar as Fertilizers to Improve Processing Tomato Production Sustainability

Domenico Ronga,Federica Caradonia,Bruno Parisi,Enrico Francia,Giulio Allesina,Simone Pedrazzi,Mario Parisi,Guido Bezzi

doi:10.3390/agronomy10010138

Abstract

The principal goal of the organic farming system (OFS) is to develop enterprises that are sustainable and harmonious with the environment. Unfortunately, the OFS yields fewer products per land than the non-organic farming system in many agricultural products. The objective of our study was to assess the effects of digestate and biochar fertilizers on yield and fruit quality of processing tomato produced under the OFS. The experiment was carried out in Po Valley, during the 2017 and 2018 growing seasons. Liquid digestate (LD), LD + biochar (LD + BC) and pelleted digestate (PD) were evaluated and compared to biochar (BC) application and unfertilized control. The results showed that plants fertilized with LD + BC recorded the maximum marketable yield (72 t ha−1), followed by BC (67 t ha−1), PD (64 t ha−1) and LD (59 t ha−1); while the lowest production (47 t ha−1) was recorded in unfertilized plants. Over the two cropping seasons, LD + BC, BC, PD, and LD, increased fruit number per plant (+15%), fruit weight (+24%), Brix t ha−1 (+41%) and reduced Bostwick index (−16%), if compared to the untreated control. Considering the overall agronomic performances, digestate and biochar can be useful options for increasing yield and quality of processing tomato production in the OFS. Hence, these fertilizers can be assessed in future research both on other crops and farming systems.

Highlights

Processing tomato (Solanum lycopersicum L.) is a globally important cash crop, grown under different environments and input regimes
The highest marketable yield displayed by Liquid digestate (LD) + BC fertilization can be related to seven main parameters: fruit number per plant, fruit weight, plant height, main stem length, aboveground biomass production, Fruit water productivity (FWP) and nitrogen applied efficiency (NAE), according to the results showed by Barrios-Masias and Jackson [49] and, Ronga et al [48], which investigated the main morphological and physiological parameter involved in increasing marketable yield under different environments (California and Italy, respectively)
Our results demonstrated that the organic fertilizers assessed in our work improved different fruit quality attributes of processing tomato in agreement with the results reported by Asami et al [72], on strawberry grown under the organic farming system (OFS)

Summary

Introduction

Processing tomato (Solanum lycopersicum L.) is a globally important cash crop, grown under different environments and input regimes. In 2019, worldwide production was estimated at ~37 million tones [1]. In the last 20 years, agriculture challenge is to provide enough and nutritious food for the growing population, minimizing its environmental impact in order to meet the sustainable development goals [2]. The organic farming system (OFS) can be an alternative approach to improve agricultural sustainability compared to the conventional one. OFS emphasizes rotating crops, adopts animal and green manure or compost to fertilize the crops, managing abiotic and biotic stress naturally, and improving biodiversity, soil and water conservations [3].

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