Development of a Simple Bioponic Method Using Manure and Offering Comparable Lettuce Yield than Hydroponics

Abstract

Using locally accessible organic materials as fertilizers in hydroponics can represent a sustainable alternative to the synthetic mineral fertilizers typically used. This study aimed at developing a simple bioponic method using chicken or goat manure on lettuce (Lactuca sativa var. Lucrecia) in the nutrient film technique, requiring few inputs. The first experiment compared nutrient solutions made from chicken or goat droppings and mineral fertilizers in terms of physico-chemical parameters, plant yields, and shoot mineral content. Organic solutions were produced in two main stages before being used on plants: (1) a simple manure maceration in water to produce stock solution, followed by (2) an aerobic digestion of the filtrated and diluted stock solution according to the total mineral nitrogen (TMN). The second experiment compared different concentrations of chicken manure stock solution (60, 80, 100, or 120 mg/L TMN) to a control mineral solution. In the first experiment, both organic treatments resulted in yields significantly lower than those of the control, probably due to nitrogen scarcity. In the second experiment, all organic treatments resulted in wet and dry shoot masses similar to those obtained with the inorganic control treatment. Produce quality was also improved, with lower shoot nitrate content. Important nitrogen losses occurred in the organic solutions during aerobic digestion, particularly in the goat treatment and in the highly concentrated treatments in stock solution during the 2nd experiment (~50–65% TMN losses). This was probably caused by the presence of residual organic matter, which resulted in excessive microbial development. It can be concluded that chicken and goat manure are suitable fertilizers for lettuce hydroponic production using this method; however, further research should be carried out to improve mineralization during digestion steps.

A Low-Tech Approach to Mobilize Nutrients from Organic Residues to Produce Bioponic Stock Solutions

“…In a new environment, bacteria that oxidize NH 4 + to NO 2 − establish faster than NO 2 − -oxidizing bacteria [38]. A more effective inoculation of biofilters in sewage sludge resulted in a nitrification rate of 42% in the MBBR [21], and, using chicken and goat manure without inoculating the biofilters, nitrification rates up to 81% were achieved using an MBBR by Szekely et al [11]. Maybe targeting an entirely different population of microorganisms for the MBBR, such as chemolithoautotrophic nitrifiers [9], could enhance the efficacy of mobilizing organic N for bioponic solutions, since no additional source of C would be needed.…”

“…In previous studies, animal manure [8][9][10][11], household waste [12], and plant residues [13,14] were used to produce bioponic solutions with varying levels of success. Thus, the challenge still evident in producing bioponic solutions is to mineralize the nutrients bound in the organic matter into soluble, plant-available forms, and provide all essential nutrients, balanced well for optimal plant growth.…”

“…Thus, the challenge still evident in producing bioponic solutions is to mineralize the nutrients bound in the organic matter into soluble, plant-available forms, and provide all essential nutrients, balanced well for optimal plant growth. The most commonly applied methods to produce bioponic solutions are the aerobic [11,[15][16][17] and anaerobic digestion [9,10,14] of organic matter in an aqueous solution.…”

“…Further, the combination of anaerobic digestion for mineralization and a subsequent aerobic treatment for nitrification has been investigated in several studies [8,12,21,22]. However, problems such as phytotoxicity, high pH, and low and imbalanced nutrient concentrations, causing poor plant growth, also occurred regularly with aerobically produced bioponic solutions [8,11,12,21,22].…”

Implications of a Climate-Smart Approach to Food and Income Security for Urban Sub-Saharan Africa: A Systematic Review

“…Urban agriculture offers farmers options for low-cost, innovative, and sustainable practices, such as hydroponics and aquaponics, which can improve yields and use water efficiently (less water), as well as soilless techniques. These options minimise the challenges of scarce urban land and water sources [33][34][35]. Further, UA systems could benefit cities with renewable energy, minimising the carbon footprint of urban food production [36].…”